Merging Yarrows

The YarrowDataset structure can be used both to describe a single image or multiple images that a part of the same dataset.

When constructing such dataset you may need to add multiple pre-existing Yarrows into an existing one or a new one, this document describes the possible ways to do this

Append another Yarrow into one

Given 2 existing YarrowDataset:

yar_dataset1 = YarrowDataset(...)
yar_dataset2 = YarrowDataset(...)

To add dataset 2 to dataset 1:

yar_dataset1.append(yar_dataset2)

This will result in the following :

  • yar_dataset2 will be unchanged

  • In yar_dataset1 The Info property will be unchanged

  • The images of yar_dataset2 will be added to yar_dataset1 only if they are not already present

    • The meta key is ignored when comparing two Image objects

  • The contributors of yar_dataset2 will be added to yar_dataset1 only if they are not already present

  • The annotations of yar_dataset2 will be added to yar_dataset1 only if they are not already present

    • The meta key is ignored when comparing two Annotation objects

    • If the images of a given annotation are already in yar_dataset1 they are relinked to the yar_dataset1 ones

    • The previous statement is also true for contributors and categories

Extend a Yarrow with a list

Given multiple existing YarrowDataset:

yar_dataset1 = YarrowDataset(...)
yar_dataset_list = [YarrowDataset(...), YarrowDataset(...), ...]

You can extend the first one with the list using:

yar_dataset1.extend(yar_dataset_list)

As a result all the Yarrows will be appended to the first one following the same rules as the append() function

To append only parts of a Yarrow

If you want to append only a subset of a Yarrow or individual element you can use the following methods:

info = Info(source="tutorial")
yar_dataset1 = YarrowDataset(info=info, images=[])

image1 = Image(...)

yar_dataset1.add_image(image1) # To add a single image
assert len(yar_dataset1.images) == 1
yar_dataset1.add_images([image1]) # To add a list of images
assert len(yar_dataset1.images) == 1 # as we already added image1, it won't be added a second time

annotation1 = Annotation(images=[image1], ...)

yar_dataset1.add_annotation(annotation1) # To add a single annotation
assert len(yar_dataset1.images) == 1 # image1 was already present so it wasn't added

!!! A copy is made before appending objects !!! With the previous code:

assert yar_dataset1.images[0] == image1 # They will be equal...
assert yar_dataset1.image[0] is not image1 # But they won't be the same object

assert yar_dataset1.annotations[0] == annotation1 # Same with annotation, they will be equal...
assert yar_dataset1.annotations[0] is not annotation1 # But they won't be the same object