napari.utils#

Classes

`Colormap`	Colormap that relates intensity values to colors.
`CyclicLabelColormap`	Color cycle with a background value.
`DirectLabelColormap`	Colormap using a direct mapping from labels to color using a dict.
`NotebookScreenshot`	Display a napari screenshot in a jupyter notebook.
`cancelable_progress`	This class inherits from progress, providing the additional ability to cancel expensive executions.
`progress`	This class inherits from tqdm and provides an interface for progress bars in the napari viewer.

Functions

napari.utils.nbscreenshot(viewer, *, canvas_only=False, alt_text=None) → NotebookScreenshot[source]#

Display a napari screenshot in a Jupyter notebook.

This is a convenience wrapper around NotebookScreenshot for the common use case of returning a rich display object directly from a notebook cell.

Parameters:

viewer (napari.Viewer) – The napari viewer.
canvas_only (bool, optional) – If False include the napari viewer frame in the screenshot, and if True then take screenshot of just the image display canvas. By default, False.
alt_text (str, optional) – Image description alternative text, for screenreader accessibility. Good alt-text describes the image and any text within the image in no more than three short, complete sentences. By default, None.

Returns:

A rich display object that renders as a PNG in notebook frontends.

Return type:

NotebookScreenshot

Examples

>>> import napari
>>> from napari.utils import nbscreenshot
>>> from skimage.data import chelsea

>>> viewer = napari.Viewer()
>>> viewer.add_image(chelsea(), name='chelsea-the-cat')
>>> nbscreenshot(viewer)
>>> # screenshot just the canvas without the napari viewer framing it
>>> nbscreenshot(viewer, canvas_only=True)

napari.utils.progrange(*args: Any, **kwargs: Any) → progress[source]#

Shorthand for progress(range(*args), **kwargs).

Adds tqdm based progress bar to napari viewer, if it exists, and returns the wrapped range object.

Returns:: wrapped range object
Return type:: progress

napari.utils.resize_dask_cache(nbytes: int | None = None, mem_fraction: float | None = None) → Cache[source]#

Create or resize the dask cache used for opportunistic caching.

The cache object is an instance of a Cache, (which wraps a cachey.Cache).

See Dask opportunistic caching

Parameters:

nbytes (int, optional) – The desired size of the cache, in bytes. If None, the cache size will autodetermined as fraction of the total memory in the system, using mem_fraction. If nbytes is 0. The cache is turned off. by default, cache size is autodetermined using mem_fraction.
mem_fraction (float, optional) – The fraction (from 0 to 1) of total memory to use for the dask cache.

Returns:

dask_cache – An instance of a Dask Cache

Return type:

dask.cache.Cache

Examples

>>> from napari.utils import resize_dask_cache
>>> cache = resize_dask_cache()  # use 25% of total memory by default

>>> # dask.Cache wraps cachey.Cache
>>> assert isinstance(cache.cache, cachey.Cache)

>>> # useful attributes
>>> cache.cache.available_bytes  # full size of cache
>>> cache.cache.total_bytes   # currently used bytes

napari.utils.sys_info(as_html: bool = False) → str[source]#

Gathers relevant module versions for troubleshooting purposes.

Parameters:: as_html (bool) – if True, info will be returned as HTML, suitable for a QTextEdit widget