napari.components.LayerList#

class napari.components.LayerList(data=())[source]#

Bases: SelectableEventedList[Layer]

List-like layer collection with built-in reordering and callback hooks.

Parameters:

data (iterable) – Iterable of napari.layer.Layer

Events:

inserting ((index: int)) – emitted before an item is inserted at index
inserted ((index: int, value: T)) – emitted after value is inserted at index
removing ((index: int)) – emitted before an item is removed at index
removed ((index: int, value: T)) – emitted after value is removed at index
moving ((index: int, new_index: int)) – emitted before an item is moved from index to new_index
moved ((index: int, new_index: int, value: T)) – emitted after value is moved from index to new_index
changed ((index: int, old_value: T, value: T)) – emitted when item at index is changed from old_value to value
changed <OVERLOAD> ((index: slice, old_value: List[_T], value: List[_T])) – emitted when item at index is changed from old_value to value
reordered ((value: self)) – emitted when the list is reordered (eg. moved/reversed).
selection.events.changed ((added: Set[_T], removed: Set[_T])) – emitted when the set changes, includes item(s) that have been added and/or removed from the set.
selection.events.active ((value: _T)) – emitted when the current item has changed.
selection.events._current ((value: _T)) – emitted when the current item has changed. (Private event)

Methods

`append`(value)	S.append(value) -- append value to the end of the sequence
`clear`()
`copy`()	Return a shallow copy of the list.
`count`(value)
`extend`(values)	S.extend(iterable) -- extend sequence by appending elements from the iterable
`get_extent`(layers)	Return extent for a given layer list.
`index`(value[, start, stop])	Return first index of value.
`insert`(index, value)	Insert `value` before index.
`link_layers`([layers, attributes])
`move`(src_index[, dest_index])	Insert object at `src_index` before `dest_index`.
`move_multiple`(sources[, dest_index])	Move a batch of sources indices, to a single destination.
`move_selected`(index, insert)	Reorder list by moving the item at index and inserting it at the insert index.
`pop`([index])	Raise IndexError if list is empty or index is out of range.
`remove`(value)	S.remove(value) -- remove first occurrence of value.
`remove_selected`()	Remove selected layers from LayerList, but first unlink them.
`reverse`()	Reverse list IN PLACE.
`save`(path, *[, selected, plugin, _writer])	Save all or only selected layers to a path using writer plugins.
`select_all`()	Select all items in the list.
`select_next`([step, shift])	Selects next item from list.
`select_previous`([shift])	Selects previous item from list.
`toggle_selected_visibility`()	Toggle visibility of selected layers
`unlink_layers`([layers, attributes])

Attributes

`extent`	Extent of layers in data and world coordinates.
`ndim`	Maximum dimensionality of layers.
`selection`	Get current selection.

Details

append(value)#: S.append(value) – append value to the end of the sequence

clear() → None -- remove all items from S#

copy() → Self#: Return a shallow copy of the list.

count(value) → integer -- return number of occurrences of value#

extend(values)#: S.extend(iterable) – extend sequence by appending elements from the iterable

property extent: Extent#: Extent of layers in data and world coordinates.

get_extent(layers: Iterable[Layer]) → Extent[source]#

Return extent for a given layer list. This function is useful for calculating the extent of a subset of layers when preparing and updating some supplementary layers. For example see the cross Vectors layer in the multiple_viewer_widget example.

Parameters:: layers (list of Layer) – list of layers for which extent should be calculated
Returns:: extent – extent for selected layers
Return type:: Extent

index(value: _L, start: int = 0, stop: int | None = None) → int#

Return first index of value.

Parameters:

value (Any) – A value to lookup. If type(value) is in the lookups functions provided for this class, then values in the list will be searched using the corresponding lookup converter function.
start (int, optional) – The starting index to search, by default 0
stop (int, optional) – The ending index to search, by default None

Returns:

The index of the value

Return type:

int

Raises:

ValueError – If the value is not present

insert(index: int, value: Layer)[source]#: Insert value before index.

move(src_index: int, dest_index: int = 0) → bool#

Insert object at src_index before dest_index.

Both indices refer to the list prior to any object removal (pre-move space).

move_multiple(sources: Iterable[int | slice], dest_index: int = 0) → int#

Move a batch of sources indices, to a single destination.

Note, if dest_index is higher than any of the sources, then the resulting position of the moved objects after the move operation is complete will be lower than dest_index.

Parameters:

sources (Sequence[int or slice]) – A sequence of indices
dest_index (int, optional) – The destination index. All sources will be inserted before this index (in pre-move space), by default 0… which has the effect of “bringing to front” everything in sources, or acting as a “reorder” method if sources contains all indices.

Returns:

The number of successful move operations completed.

Return type:

int

Raises:

TypeError – If the destination index is a slice, or any of the source indices are not int or slice.

move_selected(index: int, insert: int)#

Reorder list by moving the item at index and inserting it at the insert index. If additional items are selected these will get inserted at the insert index too. This allows for rearranging the list based on dragging and dropping a selection of items, where index is the index of the primary item being dragged, and insert is the index of the drop location, and the selection indicates if multiple items are being dragged. If the moved layer is not selected select it.

This method is deprecated. Please use layers.move_multiple with layers.selection instead.

Parameters:

index (int) – Index of primary item to be moved
insert (int) – Index that item(s) will be inserted at

property ndim: int#

Maximum dimensionality of layers.

Defaults to 2 if no data is present.

Returns:: ndim
Return type:: int

pop([index]) → item -- remove and return item at index (default last).#: Raise IndexError if list is empty or index is out of range.

remove(value)#: S.remove(value) – remove first occurrence of value. Raise ValueError if the value is not present.

remove_selected()[source]#: Remove selected layers from LayerList, but first unlink them.

reverse() → None#: Reverse list IN PLACE.

save(path: str, *, selected: bool = False, plugin: str | None = None, _writer: WriterContribution | None = None) → List[str][source]#

Save all or only selected layers to a path using writer plugins.

If plugin is not provided and only one layer is targeted, then we directly call the corresponding``napari_write_<layer_type>`` hook (see single layer writer hookspecs) which will loop through implementations and stop when the first one returns a non-None result. The order in which implementations are called can be changed with the Plugin sorter in the GUI or with the corresponding hook’s bring_to_front() method.

If plugin is not provided and multiple layers are targeted, then we call napari_get_writer() which loops through plugins to find the first one that knows how to handle the combination of layers and is able to write the file. If no plugins offer napari_get_writer() for that combination of layers then the default napari_get_writer() will create a folder and call napari_write_<layer_type> for each layer using the Layer.name variable to modify the path such that the layers are written to unique files in the folder.

If plugin is provided and a single layer is targeted, then we call the napari_write_<layer_type> for that plugin, and if it fails we error.

If plugin is provided and multiple layers are targeted, then we call we call napari_get_writer() for that plugin, and if it doesn`t return a WriterFunction we error, otherwise we call it and if that fails if it we error.

Parameters:

path (str) – A filepath, directory, or URL to open. Extensions may be used to specify output format (provided a plugin is available for the requested format).
selected (bool) – Optional flag to only save selected layers. False by default.
plugin (str, optional) – Name of the plugin to use for saving. If None then all plugins corresponding to appropriate hook specification will be looped through to find the first one that can save the data.
_writer (WriterContribution, optional) – private: npe2 specific writer override.

Returns:

File paths of any files that were written.

Return type:

list of str

select_all()#: Select all items in the list.

select_next(step=1, shift=False)#: Selects next item from list.

select_previous(shift=False)#: Selects previous item from list.

property selection: Selection[_S]#: Get current selection.

toggle_selected_visibility()[source]#: Toggle visibility of selected layers