kwcoco

The Kitware COCO module defines a variant of the Microsoft COCO format, originally developed for the “collected images in context” object detection challenge. We are backwards compatible with the original module, but we also have improved implementations in several places, including segmentations, keypoints, annotation tracks, multi-spectral images, and videos (which represents a generic sequence of images).

A kwcoco file is a “manifest” that serves as a single reference that points to all images, categories, and annotations in a computer vision dataset. Thus, when applying an algorithm to a dataset, it is sufficient to have the algorithm take one dataset parameter: the path to the kwcoco file. Generally a kwcoco file will live in a “bundle” directory along with the data that it references, and paths in the kwcoco file will be relative to the location of the kwcoco file itself.

The main data structure in this model is largely based on the implementation in https://github.com/cocodataset/cocoapi It uses the same efficient core indexing data structures, but in our implementation the indexing can be optionally turned off, functions are silent by default (with the exception of long running processes, which optionally show progress by default). We support helper functions that add and remove images, categories, and annotations.

The kwcoco.CocoDataset class is capable of dynamic addition and removal of categories, images, and annotations. Has better support for keypoints and segmentation formats than the original COCO format. Despite being written in Python, this data structure is reasonably efficient.

>>> import kwcoco
>>> import json
>>> # Create demo data
>>> demo = kwcoco.CocoDataset.demo()
>>> # Reroot can switch between absolute / relative-paths
>>> demo.reroot(absolute=True)
>>> # could also use demo.dump / demo.dumps, but this is more explicit
>>> text = json.dumps(demo.dataset)
>>> with open('demo.json', 'w') as file:
>>>    file.write(text)

>>> # Read from disk
>>> self = kwcoco.CocoDataset('demo.json')

>>> # Add data
>>> cid = self.add_category('Cat')
>>> gid = self.add_image('new-img.jpg')
>>> aid = self.add_annotation(image_id=gid, category_id=cid, bbox=[0, 0, 100, 100])

>>> # Remove data
>>> self.remove_annotations([aid])
>>> self.remove_images([gid])
>>> self.remove_categories([cid])

>>> # Look at data
>>> import ubelt as ub
>>> print(ub.repr2(self.basic_stats(), nl=1))
>>> print(ub.repr2(self.extended_stats(), nl=2))
>>> print(ub.repr2(self.boxsize_stats(), nl=3))
>>> print(ub.repr2(self.category_annotation_frequency()))


>>> # Inspect data
>>> # xdoctest: +REQUIRES(module:kwplot)
>>> import kwplot
>>> kwplot.autompl()
>>> self.show_image(gid=1)

>>> # Access single-item data via imgs, cats, anns
>>> cid = 1
>>> self.cats[cid]
{'id': 1, 'name': 'astronaut', 'supercategory': 'human'}

>>> gid = 1
>>> self.imgs[gid]
{'id': 1, 'file_name': 'astro.png', 'url': 'https://i.imgur.com/KXhKM72.png'}

>>> aid = 3
>>> self.anns[aid]
{'id': 3, 'image_id': 1, 'category_id': 3, 'line': [326, 369, 500, 500]}

>>> # Access multi-item data via the annots and images helper objects
>>> aids = self.index.gid_to_aids[2]
>>> annots = self.annots(aids)

>>> print('annots = {}'.format(ub.repr2(annots, nl=1, sv=1)))
annots = <Annots(num=2)>

>>> annots.lookup('category_id')
[6, 4]

>>> annots.lookup('bbox')
[[37, 6, 230, 240], [124, 96, 45, 18]]

>>> # built in conversions to efficient kwimage array DataStructures
>>> print(ub.repr2(annots.detections.data, sv=1))
{
    'boxes': <Boxes(xywh,
                 array([[ 37.,   6., 230., 240.],
                        [124.,  96.,  45.,  18.]], dtype=float32))>,
    'class_idxs': [5, 3],
    'keypoints': <PointsList(n=2)>,
    'segmentations': <PolygonList(n=2)>,
}

>>> gids = list(self.imgs.keys())
>>> images = self.images(gids)
>>> print('images = {}'.format(ub.repr2(images, nl=1, sv=1)))
images = <Images(num=3)>

>>> images.lookup('file_name')
['astro.png', 'carl.png', 'stars.png']

>>> print('images.annots = {}'.format(images.annots))
images.annots = <AnnotGroups(n=3, m=3.7, s=3.9)>

>>> print('images.annots.cids = {!r}'.format(images.annots.cids))
images.annots.cids = [[1, 2, 3, 4, 5, 5, 5, 5, 5], [6, 4], []]

CocoDataset API

The following is a logical grouping of the public kwcoco.CocoDataset API attributes and methods. See the in-code documentation for further details.

CocoDataset classmethods (via MixinCocoExtras)

CocoDataset classmethods (via CocoDataset)

CocoDataset slots

  • kwcoco.CocoDataset.index - an efficient lookup index into the coco data structure. The index defines its own attributes like anns, cats, imgs, gid_to_aids, file_name_to_img, etc. See CocoIndex for more details on which attributes are available.

  • kwcoco.CocoDataset.hashid - If computed, this will be a hash uniquely identifing the dataset. To ensure this is computed see kwcoco.coco_dataset.MixinCocoExtras._build_hashid().

  • kwcoco.CocoDataset.hashid_parts -

  • kwcoco.CocoDataset.tag - A tag indicating the name of the dataset.

  • kwcoco.CocoDataset.dataset - raw json data structure. This is the base dictionary that contains {‘annotations’: List, ‘images’: List, ‘categories’: List}

  • kwcoco.CocoDataset.bundle_dpath - If known, this is the root path that all image file names are relative to. This can also be manually overwritten by the user.

  • kwcoco.CocoDataset.assets_dpath -

  • kwcoco.CocoDataset.cache_dpath -

CocoDataset properties

  • kwcoco.CocoDataset.anns -

  • kwcoco.CocoDataset.cats -

  • kwcoco.CocoDataset.cid_to_aids -

  • kwcoco.CocoDataset.data_fpath -

  • kwcoco.CocoDataset.data_root -

  • kwcoco.CocoDataset.fpath - if known, this stores the filepath the dataset was loaded from

  • kwcoco.CocoDataset.gid_to_aids -

  • kwcoco.CocoDataset.img_root -

  • kwcoco.CocoDataset.imgs -

  • kwcoco.CocoDataset.n_annots -

  • kwcoco.CocoDataset.n_cats -

  • kwcoco.CocoDataset.n_images -

  • kwcoco.CocoDataset.n_videos -

  • kwcoco.CocoDataset.name_to_cat -

CocoDataset methods (via MixinCocoAddRemove)

CocoDataset methods (via MixinCocoObjects)

CocoDataset methods (via MixinCocoStats)

CocoDataset methods (via MixinCocoAccessors)

CocoDataset methods (via CocoDataset)

CocoDataset methods (via MixinCocoExtras)

CocoDataset methods (via MixinCocoDraw)

Subpackages

Submodules

Package Contents

Classes

AbstractCocoDataset

This is a common base for all variants of the Coco Dataset

CategoryTree

Wrapper that maintains flat or hierarchical category information.

CocoDataset

The main coco dataset class with a json dataset backend.

ChannelSpec

Parse and extract information about network input channel specs for

FusedChannelSpec

A specific type of channel spec with only one early fused stream.
class kwcoco.AbstractCocoDataset[source]

Bases: abc.ABC

This is a common base for all variants of the Coco Dataset

At the time of writing there is kwcoco.CocoDataset (which is the dictionary-based backend), and the kwcoco.coco_sql_dataset.CocoSqlDataset, which is experimental.

class kwcoco.CategoryTree(graph=None)[source]

Bases: ubelt.NiceRepr

Wrapper that maintains flat or hierarchical category information.

Helps compute softmaxes and probabilities for tree-based categories where a directed edge (A, B) represents that A is a superclass of B.

Note

There are three basic properties that this object maintains:

node:
    Alphanumeric string names that should be generally descriptive.
    Using spaces and special characters in these names is
    discouraged, but can be done.  This is the COCO category "name"
    attribute.  For categories this may be denoted as (name, node,
    cname, catname).

id:
    The integer id of a category should ideally remain consistent.
    These are often given by a dataset (e.g. a COCO dataset).  This
    is the COCO category "id" attribute. For categories this is
    often denoted as (id, cid).

index:
    Contigous zero-based indices that indexes the list of
    categories.  These should be used for the fastest access in
    backend computation tasks. Typically corresponds to the
    ordering of the channels in the final linear layer in an
    associated model.  For categories this is often denoted as
    (index, cidx, idx, or cx).
Variables

  • idx_to_node (List[str]) – a list of class names. Implicitly maps from index to category name.

  • id_to_node (Dict[int, str]) – maps integer ids to category names

  • node_to_id (Dict[str, int]) – maps category names to ids

  • node_to_idx (Dict[str, int]) – maps category names to indexes

  • graph (networkx.Graph) – a Graph that stores any hierarchy information. For standard mutually exclusive classes, this graph is edgeless. Nodes in this graph can maintain category attributes / properties.

  • idx_groups (List[List[int]]) – groups of category indices that share the same parent category.

Example

>>> from kwcoco.category_tree import *
>>> graph = nx.from_dict_of_lists({
>>>     'background': [],
>>>     'foreground': ['animal'],
>>>     'animal': ['mammal', 'fish', 'insect', 'reptile'],
>>>     'mammal': ['dog', 'cat', 'human', 'zebra'],
>>>     'zebra': ['grevys', 'plains'],
>>>     'grevys': ['fred'],
>>>     'dog': ['boxer', 'beagle', 'golden'],
>>>     'cat': ['maine coon', 'persian', 'sphynx'],
>>>     'reptile': ['bearded dragon', 't-rex'],
>>> }, nx.DiGraph)
>>> self = CategoryTree(graph)
>>> print(self)
<CategoryTree(nNodes=22, maxDepth=6, maxBreadth=4...)>

Example

>>> # The coerce classmethod is the easiest way to create an instance
>>> import kwcoco
>>> kwcoco.CategoryTree.coerce(['a', 'b', 'c'])
<CategoryTree(nNodes=3, nodes=['a', 'b', 'c']) ...
>>> kwcoco.CategoryTree.coerce(4)
<CategoryTree(nNodes=4, nodes=['class_1', 'class_2', 'class_3', ...
>>> kwcoco.CategoryTree.coerce(4)
copy(self)
classmethod from_mutex(cls, nodes, bg_hack=True)
Parameters

nodes (List[str]) – or a list of class names (in which case they will all be assumed to be mutually exclusive)

Example

>>> print(CategoryTree.from_mutex(['a', 'b', 'c']))
<CategoryTree(nNodes=3, ...)>
classmethod from_json(cls, state)
Parameters

state (Dict) – see __getstate__ / __json__ for details

classmethod from_coco(cls, categories)

Create a CategoryTree object from coco categories

Parameters

List[Dict] – list of coco-style categories

classmethod coerce(cls, data, **kw)

Attempt to coerce data as a CategoryTree object.

This is primarily useful for when the software stack depends on categories being represent

This will work if the input data is a specially formatted json dict, a list of mutually exclusive classes, or if it is already a CategoryTree. Otherwise an error will be thrown.

Parameters

  • data (object) – a known representation of a category tree.

  • **kwargs – input type specific arguments

Returns

self

Return type

CategoryTree

Raises

  • TypeError - if the input format is unknown –

  • ValueError - if kwargs are not compatible with the input format –

Example

>>> import kwcoco
>>> classes1 = kwcoco.CategoryTree.coerce(3)  # integer
>>> classes2 = kwcoco.CategoryTree.coerce(classes1.__json__())  # graph dict
>>> classes3 = kwcoco.CategoryTree.coerce(['class_1', 'class_2', 'class_3'])  # mutex list
>>> classes4 = kwcoco.CategoryTree.coerce(classes1.graph)  # nx Graph
>>> classes5 = kwcoco.CategoryTree.coerce(classes1)  # cls
>>> # xdoctest: +REQUIRES(module:ndsampler)
>>> import ndsampler
>>> classes6 = ndsampler.CategoryTree.coerce(3)
>>> classes7 = ndsampler.CategoryTree.coerce(classes1)
>>> classes8 = kwcoco.CategoryTree.coerce(classes6)
classmethod demo(cls, key='coco', **kwargs)
Parameters

key (str) – specify which demo dataset to use. Can be ‘coco’ (which uses the default coco demo data). Can be ‘btree’ which creates a binary tree and accepts kwargs ‘r’ and ‘h’ for branching-factor and height. Can be ‘btree2’, which is the same as btree but returns strings

CommandLine

xdoctest -m ~/code/kwcoco/kwcoco/category_tree.py CategoryTree.demo

Example

>>> from kwcoco.category_tree import *
>>> self = CategoryTree.demo()
>>> print('self = {}'.format(self))
self = <CategoryTree(nNodes=10, maxDepth=2, maxBreadth=4...)>
to_coco(self)

Converts to a coco-style data structure

Yields

Dict – coco category dictionaries

id_to_idx(self)

Example

>>> import kwcoco
>>> self = kwcoco.CategoryTree.demo()
>>> self.id_to_idx[1]
idx_to_id(self)

Example

>>> import kwcoco
>>> self = kwcoco.CategoryTree.demo()
>>> self.idx_to_id[0]
idx_to_ancestor_idxs(self, include_self=True)

Mapping from a class index to its ancestors

Parameters

include_self (bool, default=True) – if True includes each node as its own ancestor.

idx_to_descendants_idxs(self, include_self=False)

Mapping from a class index to its descendants (including itself)

Parameters

include_self (bool, default=False) – if True includes each node as its own descendant.

idx_pairwise_distance(self)

Get a matrix encoding the distance from one class to another.

Distances

  • from parents to children are positive (descendants),

  • from children to parents are negative (ancestors),

  • between unreachable nodes (wrt to forward and reverse graph) are nan.

__len__(self)
__iter__(self)
__getitem__(self, index)
__contains__(self, node)
__json__(self)

Example

>>> import pickle
>>> self = CategoryTree.demo()
>>> print('self = {!r}'.format(self.__json__()))
__getstate__(self)

Serializes information in this class

Example

>>> from kwcoco.category_tree import *
>>> import pickle
>>> self = CategoryTree.demo()
>>> state = self.__getstate__()
>>> serialization = pickle.dumps(self)
>>> recon = pickle.loads(serialization)
>>> assert recon.__json__() == self.__json__()
__setstate__(self, state)
__nice__(self)
is_mutex(self)

Returns True if all categories are mutually exclusive (i.e. flat)

If true, then the classes may be represented as a simple list of class names without any loss of information, otherwise the underlying category graph is necessary to preserve all knowledge.

Todo

  • [ ] what happens when we have a dummy root?

property num_classes(self)
property class_names(self)
property category_names(self)
property cats(self)

Returns a mapping from category names to category attributes.

If this category tree was constructed from a coco-dataset, then this will contain the coco category attributes.

Returns

Dict[str, Dict[str, object]]

Example

>>> from kwcoco.category_tree import *
>>> self = CategoryTree.demo()
>>> print('self.cats = {!r}'.format(self.cats))
index(self, node)

Return the index that corresponds to the category name

_build_index(self)

construct lookup tables

show(self)
class kwcoco.CocoDataset(data=None, tag=None, bundle_dpath=None, img_root=None, fname=None, autobuild=True)[source]

Bases: kwcoco.abstract_coco_dataset.AbstractCocoDataset, MixinCocoAddRemove, MixinCocoStats, MixinCocoObjects, MixinCocoDraw, MixinCocoAccessors, MixinCocoExtras, MixinCocoIndex, MixinCocoDepricate, ubelt.NiceRepr

The main coco dataset class with a json dataset backend.

Variables

  • dataset (Dict) – raw json data structure. This is the base dictionary that contains {‘annotations’: List, ‘images’: List, ‘categories’: List}

  • index (CocoIndex) – an efficient lookup index into the coco data structure. The index defines its own attributes like anns, cats, imgs, gid_to_aids, file_name_to_img, etc. See CocoIndex for more details on which attributes are available.

  • fpath (PathLike | None) – if known, this stores the filepath the dataset was loaded from

  • tag (str) – A tag indicating the name of the dataset.

  • bundle_dpath (PathLike | None) – If known, this is the root path that all image file names are relative to. This can also be manually overwritten by the user.

  • hashid (str | None) – If computed, this will be a hash uniquely identifing the dataset. To ensure this is computed see kwcoco.coco_dataset.MixinCocoExtras._build_hashid().

References

http://cocodataset.org/#format http://cocodataset.org/#download

CommandLine

python -m kwcoco.coco_dataset CocoDataset --show

Example

>>> from kwcoco.coco_dataset import demo_coco_data
>>> import kwcoco
>>> import ubelt as ub
>>> # Returns a coco json structure
>>> dataset = demo_coco_data()
>>> # Pass the coco json structure to the API
>>> self = kwcoco.CocoDataset(dataset, tag='demo')
>>> # Now you can access the data using the index and helper methods
>>> #
>>> # Start by looking up an image by it's COCO id.
>>> image_id = 1
>>> img = self.index.imgs[image_id]
>>> print(ub.repr2(img, nl=1))
{
    'file_name': 'astro.png',
    'id': 1,
    'url': 'https://i.imgur.com/KXhKM72.png',
}
>>> #
>>> # Use the (gid_to_aids) index to lookup annotations in the iamge
>>> annotation_id = sorted(self.index.gid_to_aids[image_id])[0]
>>> ann = self.index.anns[annotation_id]
>>> print(ub.repr2(ub.dict_diff(ann, {'segmentation'}), nl=1))
{
    'bbox': [10, 10, 360, 490],
    'category_id': 1,
    'id': 1,
    'image_id': 1,
    'keypoints': [247, 101, 2, 202, 100, 2],
}
>>> #
>>> # Use annotation category id to look up that information
>>> category_id = ann['category_id']
>>> cat = self.index.cats[category_id]
>>> print('cat = {}'.format(ub.repr2(cat, nl=1)))
cat = {
    'id': 1,
    'name': 'astronaut',
    'supercategory': 'human',
}
>>> #
>>> # Now play with some helper functions, like extended statistics
>>> extended_stats = self.extended_stats()
>>> print('extended_stats = {}'.format(ub.repr2(extended_stats, nl=1, precision=2)))
extended_stats = {
    'annots_per_img': {'mean': 3.67, 'std': 3.86, 'min': 0.00, 'max': 9.00, 'nMin': 1, 'nMax': 1, 'shape': (3,)},
    'imgs_per_cat': {'mean': 0.88, 'std': 0.60, 'min': 0.00, 'max': 2.00, 'nMin': 2, 'nMax': 1, 'shape': (8,)},
    'cats_per_img': {'mean': 2.33, 'std': 2.05, 'min': 0.00, 'max': 5.00, 'nMin': 1, 'nMax': 1, 'shape': (3,)},
    'annots_per_cat': {'mean': 1.38, 'std': 1.49, 'min': 0.00, 'max': 5.00, 'nMin': 2, 'nMax': 1, 'shape': (8,)},
    'imgs_per_video': {'empty_list': True},
}
>>> # You can "draw" a raster of the annotated image with cv2
>>> canvas = self.draw_image(2)
>>> # Or if you have matplotlib you can "show" the image with mpl objects
>>> # xdoctest: +REQUIRES(--show)
>>> from matplotlib import pyplot as plt
>>> fig = plt.figure()
>>> ax1 = fig.add_subplot(1, 2, 1)
>>> self.show_image(gid=2)
>>> ax2 = fig.add_subplot(1, 2, 2)
>>> ax2.imshow(canvas)
>>> ax1.set_title('show with matplotlib')
>>> ax2.set_title('draw with cv2')
>>> plt.show()
property fpath(self)

In the future we will deprecate img_root for bundle_dpath

_infer_dirs(self)
classmethod from_data(CocoDataset, data, bundle_dpath=None, img_root=None)

Constructor from a json dictionary

classmethod from_image_paths(CocoDataset, gpaths, bundle_dpath=None, img_root=None)

Constructor from a list of images paths.

This is a convinience method.

Parameters

gpaths (List[str]) – list of image paths

Example

>>> coco_dset = CocoDataset.from_image_paths(['a.png', 'b.png'])
>>> assert coco_dset.n_images == 2
classmethod from_coco_paths(CocoDataset, fpaths, max_workers=0, verbose=1, mode='thread', union='try')

Constructor from multiple coco file paths.

Loads multiple coco datasets and unions the result

Note

if the union operation fails, the list of individually loaded files is returned instead.

Parameters

  • fpaths (List[str]) – list of paths to multiple coco files to be loaded and unioned.

  • max_workers (int, default=0) – number of worker threads / processes

  • verbose (int) – verbosity level

  • mode (str) – thread, process, or serial

  • union (str | bool, default=’try’) – If True, unions the result datasets after loading. If False, just returns the result list. If ‘try’, then try to preform the union, but return the result list if it fails.

copy(self)

Deep copies this object

Example

>>> from kwcoco.coco_dataset import *
>>> self = CocoDataset.demo()
>>> new = self.copy()
>>> assert new.imgs[1] is new.dataset['images'][0]
>>> assert new.imgs[1] == self.dataset['images'][0]
>>> assert new.imgs[1] is not self.dataset['images'][0]
__nice__(self)
dumps(self, indent=None, newlines=False)

Writes the dataset out to the json format

Parameters

newlines (bool) – if True, each annotation, image, category gets its own line

Note

Using newlines=True is similar to:

print(ub.repr2(dset.dataset, nl=2, trailsep=False)) However, the above may not output valid json if it contains ndarrays.

Example

>>> from kwcoco.coco_dataset import *
>>> import json
>>> self = CocoDataset.demo()
>>> text = self.dumps(newlines=True)
>>> print(text)
>>> self2 = CocoDataset(json.loads(text), tag='demo2')
>>> assert self2.dataset == self.dataset
>>> assert self2.dataset is not self.dataset

>>> text = self.dumps(newlines=True)
>>> print(text)
>>> self2 = CocoDataset(json.loads(text), tag='demo2')
>>> assert self2.dataset == self.dataset
>>> assert self2.dataset is not self.dataset
dump(self, file, indent=None, newlines=False)

Writes the dataset out to the json format

Parameters

  • file (PathLike | FileLike) – Where to write the data. Can either be a path to a file or an open file pointer / stream.

  • newlines (bool) – if True, each annotation, image, category gets its own line.

Example

>>> import tempfile
>>> from kwcoco.coco_dataset import *
>>> self = CocoDataset.demo()
>>> file = tempfile.NamedTemporaryFile('w')
>>> self.dump(file)
>>> file.seek(0)
>>> text = open(file.name, 'r').read()
>>> print(text)
>>> file.seek(0)
>>> dataset = json.load(open(file.name, 'r'))
>>> self2 = CocoDataset(dataset, tag='demo2')
>>> assert self2.dataset == self.dataset
>>> assert self2.dataset is not self.dataset

>>> file = tempfile.NamedTemporaryFile('w')
>>> self.dump(file, newlines=True)
>>> file.seek(0)
>>> text = open(file.name, 'r').read()
>>> print(text)
>>> file.seek(0)
>>> dataset = json.load(open(file.name, 'r'))
>>> self2 = CocoDataset(dataset, tag='demo2')
>>> assert self2.dataset == self.dataset
>>> assert self2.dataset is not self.dataset
_check_json_serializable(self, verbose=1)

Debug which part of a coco dataset might not be json serializable

_check_integrity(self)

perform all checks

_check_index(self)

Example

>>> import kwcoco
>>> self = kwcoco.CocoDataset.demo()
>>> self._check_index()
>>> # Force a failure
>>> self.index.anns.pop(1)
>>> self.index.anns.pop(2)
>>> import pytest
>>> with pytest.raises(AssertionError):
>>>     self._check_index()
_check_pointers(self, verbose=1)

Check that all category and image ids referenced by annotations exist

_build_index(self)
union(*others, disjoint_tracks=True, **kwargs)

Merges multiple CocoDataset items into one. Names and associations are retained, but ids may be different.

Parameters

  • *others – a series of CocoDatasets that we will merge. Note, if called as an instance method, the “self” instance will be the first item in the “others” list. But if called like a classmethod, “others” will be empty by default.

  • disjoint_tracks (bool, default=True) – if True, we will assume track-ids are disjoint and if two datasets share the same track-id, we will disambiguate them. Otherwise they will be copied over as-is.

  • **kwargs – constructor options for the new merged CocoDataset

Returns

a new merged coco dataset

Return type

CocoDataset

CommandLine

xdoctest -m kwcoco.coco_dataset CocoDataset.union

Example

>>> # Test union works with different keypoint categories
>>> dset1 = CocoDataset.demo('shapes1')
>>> dset2 = CocoDataset.demo('shapes2')
>>> dset1.remove_keypoint_categories(['bot_tip', 'mid_tip', 'right_eye'])
>>> dset2.remove_keypoint_categories(['top_tip', 'left_eye'])
>>> dset_12a = CocoDataset.union(dset1, dset2)
>>> dset_12b = dset1.union(dset2)
>>> dset_21 = dset2.union(dset1)
>>> def add_hist(h1, h2):
>>>     return {k: h1.get(k, 0) + h2.get(k, 0) for k in set(h1) | set(h2)}
>>> kpfreq1 = dset1.keypoint_annotation_frequency()
>>> kpfreq2 = dset2.keypoint_annotation_frequency()
>>> kpfreq_want = add_hist(kpfreq1, kpfreq2)
>>> kpfreq_got1 = dset_12a.keypoint_annotation_frequency()
>>> kpfreq_got2 = dset_12b.keypoint_annotation_frequency()
>>> assert kpfreq_want == kpfreq_got1
>>> assert kpfreq_want == kpfreq_got2

>>> # Test disjoint gid datasets
>>> import kwcoco
>>> dset1 = kwcoco.CocoDataset.demo('shapes3')
>>> for new_gid, img in enumerate(dset1.dataset['images'], start=10):
>>>     for aid in dset1.gid_to_aids[img['id']]:
>>>         dset1.anns[aid]['image_id'] = new_gid
>>>     img['id'] = new_gid
>>> dset1.index.clear()
>>> dset1._build_index()
>>> # ------
>>> dset2 = kwcoco.CocoDataset.demo('shapes2')
>>> for new_gid, img in enumerate(dset2.dataset['images'], start=100):
>>>     for aid in dset2.gid_to_aids[img['id']]:
>>>         dset2.anns[aid]['image_id'] = new_gid
>>>     img['id'] = new_gid
>>> dset1.index.clear()
>>> dset2._build_index()
>>> others = [dset1, dset2]
>>> merged = kwcoco.CocoDataset.union(*others)
>>> print('merged = {!r}'.format(merged))
>>> print('merged.imgs = {}'.format(ub.repr2(merged.imgs, nl=1)))
>>> assert set(merged.imgs) & set([10, 11, 12, 100, 101]) == set(merged.imgs)

>>> # Test data is not preserved
>>> dset2 = kwcoco.CocoDataset.demo('shapes2')
>>> dset1 = kwcoco.CocoDataset.demo('shapes3')
>>> others = (dset1, dset2)
>>> cls = self = kwcoco.CocoDataset
>>> merged = cls.union(*others)
>>> print('merged = {!r}'.format(merged))
>>> print('merged.imgs = {}'.format(ub.repr2(merged.imgs, nl=1)))
>>> assert set(merged.imgs) & set([1, 2, 3, 4, 5]) == set(merged.imgs)

>>> # Test track-ids are mapped correctly
>>> dset1 = kwcoco.CocoDataset.demo('vidshapes1')
>>> dset2 = kwcoco.CocoDataset.demo('vidshapes2')
>>> dset3 = kwcoco.CocoDataset.demo('vidshapes3')
>>> others = (dset1, dset2, dset3)
>>> for dset in others:
>>>     [a.pop('segmentation', None) for a in dset.index.anns.values()]
>>>     [a.pop('keypoints', None) for a in dset.index.anns.values()]
>>> cls = self = kwcoco.CocoDataset
>>> merged = cls.union(*others, disjoint_tracks=1)
>>> print('dset1.anns = {}'.format(ub.repr2(dset1.anns, nl=1)))
>>> print('dset2.anns = {}'.format(ub.repr2(dset2.anns, nl=1)))
>>> print('dset3.anns = {}'.format(ub.repr2(dset3.anns, nl=1)))
>>> print('merged.anns = {}'.format(ub.repr2(merged.anns, nl=1)))

Example

>>> import kwcoco
>>> # Test empty union
>>> empty_union = kwcoco.CocoDataset.union()
>>> assert len(empty_union.index.imgs) == 0

Todo

  • [ ] are supercategories broken?

  • [ ] reuse image ids where possible

  • [ ] reuse annotation / category ids where possible

  • [X] handle case where no inputs are given

  • [x] disambiguate track-ids

  • [x] disambiguate video-ids

subset(self, gids, copy=False, autobuild=True)

Return a subset of the larger coco dataset by specifying which images to port. All annotations in those images will be taken.

Parameters

  • gids (List[int]) – image-ids to copy into a new dataset

  • copy (bool, default=False) – if True, makes a deep copy of all nested attributes, otherwise makes a shallow copy.

  • autobuild (bool, default=True) – if True will automatically build the fast lookup index.

Example

>>> self = CocoDataset.demo()
>>> gids = [1, 3]
>>> sub_dset = self.subset(gids)
>>> assert len(self.index.gid_to_aids) == 3
>>> assert len(sub_dset.gid_to_aids) == 2

Example

>>> import kwcoco
>>> self = kwcoco.CocoDataset.demo('vidshapes2')
>>> gids = [1, 2]
>>> sub_dset = self.subset(gids, copy=True)
>>> assert len(sub_dset.index.videos) == 1
>>> assert len(self.index.videos) == 2

Example

>>> self = CocoDataset.demo()
>>> sub1 = self.subset([1])
>>> sub2 = self.subset([2])
>>> sub3 = self.subset([3])
>>> others = [sub1, sub2, sub3]
>>> rejoined = CocoDataset.union(*others)
>>> assert len(sub1.anns) == 9
>>> assert len(sub2.anns) == 2
>>> assert len(sub3.anns) == 0
>>> assert rejoined.basic_stats() == self.basic_stats()
view_sql(self, force_rewrite=False, memory=False)

Create a cached SQL interface to this dataset suitable for large scale multiprocessing use cases.

Parameters

  • force_rewrite (bool, default=False) – if True, forces an update to any existing cache file on disk

  • memory (bool, default=False) – if True, the database is constructed in memory.

Note

This view cache is experimental and currently depends on the timestamp of the file pointed to by self.fpath. In other words dont use this on in-memory datasets.

class kwcoco.ChannelSpec(spec, parsed=None)[source]

Bases: BaseChannelSpec

Parse and extract information about network input channel specs for early or late fusion networks.

Behaves like a dictionary of FusedChannelSpec objects

Todo

  • [ ] Rename to something that indicates this is a collection of

    FusedChannelSpec? MultiChannelSpec?

Note

This class name and API is in flux and subject to change.

Note

The pipe (‘|’) character represents an early-fused input stream, and order matters (it is non-communative).

The comma (‘,’) character separates different inputs streams/branches for a multi-stream/branch network which will be lated fused. Order does not matter

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> # Integer spec
>>> ChannelSpec.coerce(3)
<ChannelSpec(u0|u1|u2) ...>

>>> # single mode spec
>>> ChannelSpec.coerce('rgb')
<ChannelSpec(rgb) ...>

>>> # early fused input spec
>>> ChannelSpec.coerce('rgb|disprity')
<ChannelSpec(rgb|disprity) ...>

>>> # late fused input spec
>>> ChannelSpec.coerce('rgb,disprity')
<ChannelSpec(rgb,disprity) ...>

>>> # early and late fused input spec
>>> ChannelSpec.coerce('rgb|ir,disprity')
<ChannelSpec(rgb|ir,disprity) ...>

Example

>>> self = ChannelSpec('gray')
>>> print('self.info = {}'.format(ub.repr2(self.info, nl=1)))
>>> self = ChannelSpec('rgb')
>>> print('self.info = {}'.format(ub.repr2(self.info, nl=1)))
>>> self = ChannelSpec('rgb|disparity')
>>> print('self.info = {}'.format(ub.repr2(self.info, nl=1)))
>>> self = ChannelSpec('rgb|disparity,disparity')
>>> print('self.info = {}'.format(ub.repr2(self.info, nl=1)))
>>> self = ChannelSpec('rgb,disparity,flowx|flowy')
>>> print('self.info = {}'.format(ub.repr2(self.info, nl=1)))

Example

>>> specs = [
>>>     'rgb',              # and rgb input
>>>     'rgb|disprity',     # rgb early fused with disparity
>>>     'rgb,disprity',     # rgb early late with disparity
>>>     'rgb|ir,disprity',  # rgb early fused with ir and late fused with disparity
>>>     3,                  # 3 unknown channels
>>> ]
>>> for spec in specs:
>>>     print('=======================')
>>>     print('spec = {!r}'.format(spec))
>>>     #
>>>     self = ChannelSpec.coerce(spec)
>>>     print('self = {!r}'.format(self))
>>>     sizes = self.sizes()
>>>     print('sizes = {!r}'.format(sizes))
>>>     print('self.info = {}'.format(ub.repr2(self.info, nl=1)))
>>>     #
>>>     item = self._demo_item((1, 1), rng=0)
>>>     inputs = self.encode(item)
>>>     components = self.decode(inputs)
>>>     input_shapes = ub.map_vals(lambda x: x.shape, inputs)
>>>     component_shapes = ub.map_vals(lambda x: x.shape, components)
>>>     print('item = {}'.format(ub.repr2(item, precision=1)))
>>>     print('inputs = {}'.format(ub.repr2(inputs, precision=1)))
>>>     print('input_shapes = {}'.format(ub.repr2(input_shapes)))
>>>     print('components = {}'.format(ub.repr2(components, precision=1)))
>>>     print('component_shapes = {}'.format(ub.repr2(component_shapes, nl=1)))
property spec(self)

The string encodeing of this spec

Returns

str

__contains__(self, key)

Example

>>> 'disparity' in ChannelSpec('rgb,disparity,flowx|flowy')
True
>>> 'gray' in ChannelSpec('rgb,disparity,flowx|flowy')
False
property info(self)
classmethod coerce(cls, data)

Attempt to interpret the data as a channel specification

Returns

ChannelSpec

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> data = FusedChannelSpec.coerce(3)
>>> assert ChannelSpec.coerce(data).spec == 'u0|u1|u2'
>>> data = ChannelSpec.coerce(3)
>>> assert data.spec == 'u0|u1|u2'
>>> assert ChannelSpec.coerce(data).spec == 'u0|u1|u2'
>>> data = ChannelSpec.coerce('u:3')
>>> assert data.normalize().spec == 'u.0|u.1|u.2'
parse(self)

Build internal representation

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> self = ChannelSpec('b1|b2|b3|rgb,B:3')
>>> print(self.parse())
>>> print(self.normalize().parse())
>>> ChannelSpec('').parse()

Example

>>> base = ChannelSpec('rgb|disparity,flowx|r|flowy')
>>> other = ChannelSpec('rgb')
>>> self = base.intersection(other)
>>> assert self.numel() == 4
concise(self)

Example

>>> self = ChannelSpec('b1|b2,b3|rgb|B.0,B.1|B.2')
>>> print(self.concise().spec)
b1|b2,b3|r|g|b|B.0,B.1:3
normalize(self)

Replace aliases with explicit single-band-per-code specs

Returns

normalized spec

Return type

ChannelSpec

Example

>>> self = ChannelSpec('b1|b2,b3|rgb,B:3')
>>> normed = self.normalize()
>>> print('self   = {}'.format(self))
>>> print('normed = {}'.format(normed))
self   = <ChannelSpec(b1|b2,b3|rgb,B:3)>
normed = <ChannelSpec(b1|b2,b3|r|g|b,B.0|B.1|B.2)>
keys(self)
values(self)
items(self)
fuse(self)

Fuse all parts into an early fused channel spec

Returns

FusedChannelSpec

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> self = ChannelSpec.coerce('b1|b2,b3|rgb,B:3')
>>> fused = self.fuse()
>>> print('self  = {}'.format(self))
>>> print('fused = {}'.format(fused))
self  = <ChannelSpec(b1|b2,b3|rgb,B:3)>
fused = <FusedChannelSpec(b1|b2|b3|rgb|B:3)>
streams(self)

Breaks this spec up into one spec for each early-fused input stream

Example

self = ChannelSpec.coerce(‘r|g,B1|B2,fx|fy’) list(map(len, self.streams()))

code_list(self)
difference(self, other)

Set difference. Remove all instances of other channels from this set of channels.

Example

>>> from kwcoco.channel_spec import *
>>> self = ChannelSpec('rgb|disparity,flowx|r|flowy')
>>> other = ChannelSpec('rgb')
>>> print(self.difference(other))
>>> other = ChannelSpec('flowx')
>>> print(self.difference(other))
<ChannelSpec(disparity,flowx|flowy)>
<ChannelSpec(r|g|b|disparity,r|flowy)>

Example

>>> from kwcoco.channel_spec import *
>>> self = ChannelSpec('a|b,c|d')
>>> new = self - {'a', 'b'}
>>> len(new.sizes()) == 1
>>> empty = new - 'c|d'
>>> assert empty.numel() == 0
intersection(self, other)

Set difference. Remove all instances of other channels from this set of channels.

Example

>>> from kwcoco.channel_spec import *
>>> self = ChannelSpec('rgb|disparity,flowx|r|flowy')
>>> other = ChannelSpec('rgb')
>>> new = self.intersection(other)
>>> print(new)
>>> print(new.numel())
>>> other = ChannelSpec('flowx')
>>> new = self.intersection(other)
>>> print(new)
>>> print(new.numel())
<ChannelSpec(r|g|b,r)>
4
<ChannelSpec(flowx)>
1
numel(self)

Total number of channels in this spec

sizes(self)

Number of dimensions for each fused stream channel

IE: The EARLY-FUSED channel sizes

Example

>>> self = ChannelSpec('rgb|disparity,flowx|flowy,B:10')
>>> self.normalize().concise()
>>> self.sizes()
unique(self, normalize=False)

Returns the unique channels that will need to be given or loaded

_item_shapes(self, dims)

Expected shape for an input item

Parameters

dims (Tuple[int, int]) – the spatial dimension

Returns

Dict[int, tuple]

_demo_item(self, dims=(4, 4), rng=None)

Create an input that satisfies this spec

Returns

an item like it might appear when its returned from the

__getitem__ method of a torch...Dataset.

Return type

dict

Example

>>> dims = (1, 1)
>>> ChannelSpec.coerce(3)._demo_item(dims, rng=0)
>>> ChannelSpec.coerce('r|g|b|disaprity')._demo_item(dims, rng=0)
>>> ChannelSpec.coerce('rgb|disaprity')._demo_item(dims, rng=0)
>>> ChannelSpec.coerce('rgb,disaprity')._demo_item(dims, rng=0)
>>> ChannelSpec.coerce('rgb')._demo_item(dims, rng=0)
>>> ChannelSpec.coerce('gray')._demo_item(dims, rng=0)
encode(self, item, axis=0, mode=1)

Given a dictionary containing preloaded components of the network inputs, build a concatenated (fused) network representations of each input stream.

Parameters

  • item (Dict[str, Tensor]) – a batch item containing unfused parts. each key should be a single-stream (optionally early fused) channel key.

  • axis (int, default=0) – concatenation dimension

Returns

mapping between input stream and its early fused tensor input.

Return type

Dict[str, Tensor]

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> import numpy as np
>>> dims = (4, 4)
>>> item = {
>>>     'rgb': np.random.rand(3, *dims),
>>>     'disparity': np.random.rand(1, *dims),
>>>     'flowx': np.random.rand(1, *dims),
>>>     'flowy': np.random.rand(1, *dims),
>>> }
>>> # Complex Case
>>> self = ChannelSpec('rgb,disparity,rgb|disparity|flowx|flowy,flowx|flowy')
>>> fused = self.encode(item)
>>> input_shapes = ub.map_vals(lambda x: x.shape, fused)
>>> print('input_shapes = {}'.format(ub.repr2(input_shapes, nl=1)))
>>> # Simpler case
>>> self = ChannelSpec('rgb|disparity')
>>> fused = self.encode(item)
>>> input_shapes = ub.map_vals(lambda x: x.shape, fused)
>>> print('input_shapes = {}'.format(ub.repr2(input_shapes, nl=1)))

Example

>>> # Case where we have to break up early fused data
>>> import numpy as np
>>> dims = (40, 40)
>>> item = {
>>>     'rgb|disparity': np.random.rand(4, *dims),
>>>     'flowx': np.random.rand(1, *dims),
>>>     'flowy': np.random.rand(1, *dims),
>>> }
>>> # Complex Case
>>> self = ChannelSpec('rgb,disparity,rgb|disparity,rgb|disparity|flowx|flowy,flowx|flowy,flowx,disparity')
>>> inputs = self.encode(item)
>>> input_shapes = ub.map_vals(lambda x: x.shape, inputs)
>>> print('input_shapes = {}'.format(ub.repr2(input_shapes, nl=1)))

>>> # xdoctest: +REQUIRES(--bench)
>>> #self = ChannelSpec('rgb|disparity,flowx|flowy')
>>> import timerit
>>> ti = timerit.Timerit(100, bestof=10, verbose=2)
>>> for timer in ti.reset('mode=simple'):
>>>     with timer:
>>>         inputs = self.encode(item, mode=0)
>>> for timer in ti.reset('mode=minimize-concat'):
>>>     with timer:
>>>         inputs = self.encode(item, mode=1)
decode(self, inputs, axis=1)

break an early fused item into its components

Parameters

  • inputs (Dict[str, Tensor]) – dictionary of components

  • axis (int, default=1) – channel dimension

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> import numpy as np
>>> dims = (4, 4)
>>> item_components = {
>>>     'rgb': np.random.rand(3, *dims),
>>>     'ir': np.random.rand(1, *dims),
>>> }
>>> self = ChannelSpec('rgb|ir')
>>> item_encoded = self.encode(item_components)
>>> batch = {k: np.concatenate([v[None, :], v[None, :]], axis=0)
...          for k, v in item_encoded.items()}
>>> components = self.decode(batch)

Example

>>> # xdoctest: +REQUIRES(module:netharn, module:torch)
>>> import torch
>>> import numpy as np
>>> dims = (4, 4)
>>> components = {
>>>     'rgb': np.random.rand(3, *dims),
>>>     'ir': np.random.rand(1, *dims),
>>> }
>>> components = ub.map_vals(torch.from_numpy, components)
>>> self = ChannelSpec('rgb|ir')
>>> encoded = self.encode(components)
>>> from netharn.data import data_containers
>>> item = {k: data_containers.ItemContainer(v, stack=True)
>>>         for k, v in encoded.items()}
>>> batch = data_containers.container_collate([item, item])
>>> components = self.decode(batch)
component_indices(self, axis=2)

Look up component indices within fused streams

Example

>>> dims = (4, 4)
>>> inputs = ['flowx', 'flowy', 'disparity']
>>> self = ChannelSpec('disparity,flowx|flowy')
>>> component_indices = self.component_indices()
>>> print('component_indices = {}'.format(ub.repr2(component_indices, nl=1)))
component_indices = {
    'disparity': ('disparity', (slice(None, None, None), slice(None, None, None), slice(0, 1, None))),
    'flowx': ('flowx|flowy', (slice(None, None, None), slice(None, None, None), slice(0, 1, None))),
    'flowy': ('flowx|flowy', (slice(None, None, None), slice(None, None, None), slice(1, 2, None))),
}
class kwcoco.FusedChannelSpec(parsed, _is_normalized=False)[source]

Bases: BaseChannelSpec

A specific type of channel spec with only one early fused stream.

The channels in this stream are non-communative

Behaves like a list of atomic-channel codes (which may represent more than 1 channel), normalized codes always represent exactly 1 channel.

Note

This class name and API is in flux and subject to change.

Todo

A special code indicating a name and some number of bands that that names contains, this would primarilly be used for large numbers of channels produced by a network. Like:

resnet_d35d060_L5:512

or

resnet_d35d060_L5[:512]

might refer to a very specific (hashed) set of resnet parameters with 512 bands

maybe we can do something slicly like:

resnet_d35d060_L5[A:B] resnet_d35d060_L5:A:B

Do we want to “just store the code” and allow for parsing later?

Or do we want to ensure the serialization is parsed before we construct the data structure?

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> import pickle
>>> self = FusedChannelSpec.coerce(3)
>>> recon = pickle.loads(pickle.dumps(self))
>>> self = ChannelSpec.coerce('a|b,c|d')
>>> recon = pickle.loads(pickle.dumps(self))
_alias_lut
_memo
_size_lut
__len__(self)
__getitem__(self, index)
classmethod concat(cls, items)
spec(self)

The string encodeing of this spec

Returns

str

unique(self)
classmethod parse(cls, spec)
classmethod coerce(cls, data)

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> FusedChannelSpec.coerce(['a', 'b', 'c'])
>>> FusedChannelSpec.coerce('a|b|c')
>>> FusedChannelSpec.coerce(3)
>>> FusedChannelSpec.coerce(FusedChannelSpec(['a']))
>>> assert FusedChannelSpec.coerce('').numel() == 0
concise(self)

Shorted the channel spec by de-normaliz slice syntax

Returns

concise spec

Return type

FusedChannelSpec

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> self = FusedChannelSpec.coerce(
>>>      'b|a|a.0|a.1|a.2|a.5|c|a.8|a.9|b.0:3|c.0')
>>> short = self.concise()
>>> long = short.normalize()
>>> numels = [c.numel() for c in [self, short, long]]
>>> print('self.spec  = {!r}'.format(self.spec))
>>> print('short.spec = {!r}'.format(short.spec))
>>> print('long.spec  = {!r}'.format(long.spec))
>>> print('numels = {!r}'.format(numels))
self.spec  = 'b|a|a.0|a.1|a.2|a.5|c|a.8|a.9|b.0:3|c.0'
short.spec = 'b|a|a:3|a.5|c|a.8:10|b:3|c.0'
long.spec  = 'b|a|a.0|a.1|a.2|a.5|c|a.8|a.9|b.0|b.1|b.2|c.0'
numels = [13, 13, 13]
>>> assert long.concise().spec == short.spec
normalize(self)

Replace aliases with explicit single-band-per-code specs

Returns

normalize spec

Return type

FusedChannelSpec

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> self = FusedChannelSpec.coerce('b1|b2|b3|rgb')
>>> normed = self.normalize()
>>> print('self = {}'.format(self))
>>> print('normed = {}'.format(normed))
self = <FusedChannelSpec(b1|b2|b3|rgb)>
normed = <FusedChannelSpec(b1|b2|b3|r|g|b)>
>>> self = FusedChannelSpec.coerce('B:1:11')
>>> normed = self.normalize()
>>> print('self = {}'.format(self))
>>> print('normed = {}'.format(normed))
self = <FusedChannelSpec(B:1:11)>
normed = <FusedChannelSpec(B.1|B.2|B.3|B.4|B.5|B.6|B.7|B.8|B.9|B.10)>
>>> self = FusedChannelSpec.coerce('B.1:11')
>>> normed = self.normalize()
>>> print('self = {}'.format(self))
>>> print('normed = {}'.format(normed))
self = <FusedChannelSpec(B.1:11)>
normed = <FusedChannelSpec(B.1|B.2|B.3|B.4|B.5|B.6|B.7|B.8|B.9|B.10)>
numel(self)

Total number of channels in this spec

sizes(self)

Returns a list indicating the size of each atomic code

Returns

List[int]

Example

>>> from kwcoco.channel_spec import *  # NOQA
>>> self = FusedChannelSpec.coerce('b1|Z:3|b2|b3|rgb')
>>> self.sizes()
[1, 3, 1, 1, 3]
>>> assert(FusedChannelSpec.parse('a.0').numel()) == 1
>>> assert(FusedChannelSpec.parse('a:0').numel()) == 0
>>> assert(FusedChannelSpec.parse('a:1').numel()) == 1
__contains__(self, key)

Example

>>> FCS = FusedChannelSpec.coerce
>>> 'disparity' in FCS('rgb|disparity|flowx|flowy')
True
>>> 'gray' in FCS('rgb|disparity|flowx|flowy')
False
code_list(self)

Return the expanded code list

as_list(self)
as_oset(self)
as_set(self)
__set__(self)
difference(self, other)

Set difference

Example

>>> FCS = FusedChannelSpec.coerce
>>> self = FCS('rgb|disparity|flowx|flowy')
>>> other = FCS('r|b')
>>> self.difference(other)
>>> other = FCS('flowx')
>>> self.difference(other)
>>> FCS = FusedChannelSpec.coerce
>>> assert len((FCS('a') - {'a'}).parsed) == 0
>>> assert len((FCS('a.0:3') - {'a.0'}).parsed) == 2
intersection(self, other)

Example

>>> FCS = FusedChannelSpec.coerce
>>> self = FCS('rgb|disparity|flowx|flowy')
>>> other = FCS('r|b|XX')
>>> self.intersection(other)
component_indices(self, axis=2)

Look up component indices within this stream

Example

>>> FCS = FusedChannelSpec.coerce
>>> self = FCS('disparity|rgb|flowx|flowy')
>>> component_indices = self.component_indices()
>>> print('component_indices = {}'.format(ub.repr2(component_indices, nl=1)))
component_indices = {
    'disparity': (slice(...), slice(...), slice(0, 1, None)),
    'flowx': (slice(...), slice(...), slice(4, 5, None)),
    'flowy': (slice(...), slice(...), slice(5, 6, None)),
    'rgb': (slice(...), slice(...), slice(1, 4, None)),
}
streams(self)

Idempotence with ChannelSpec.streams()

fuse(self)

Idempotence with ChannelSpec.streams()