plotting

plotting

Plotting utilities for planetary image data.

Provides common visualization helpers for planetary science: percentile stretching, grayscale image display, sun direction indicators.

Functions

Name	Description
add_sun_indicator	Add a sun direction indicator to an image plot. Experimental.
imshow_gray	Display a grayscale image with optional percentile stretch.
imshow_with_sun	Display a grayscale image with a sun direction indicator. Experimental.
percentile_stretch	Compute display limits from percentiles, ignoring zeros and NaN.

add_sun_indicator

plotting.add_sun_indicator(
    ax,
    sun_azimuth_deg,
    position='upper right',
    length=0.12,
    color='yellow',
    inner_color='orange',
)

Add a sun direction indicator to an image plot. Experimental.

.. warning::

Experimental. The azimuth-convention handoff is not fully validated: this function expects clockwise-from-image-top (the PDS SUB_SOLAR_AZIMUTH convention for unprojected images), but :meth:planetarypy.spice.spicer.Spicer.solar_azimuth_at returns clockwise-from-north (geographic). They agree only when image-north points up; otherwise you must rotate by the image’s north azimuth before passing the value here. Placement and appearance may change.

The indicator is a small compass glyph (sun ball + arrow) drawn in a corner, pointing toward the sun. It is rendered in axes-fraction coordinates, so it neither rescales the image nor depends on the image’s origin.

Parameters

Name	Type	Description	Default
ax	matplotlib.axes.Axes	The axes containing the image.	required
sun_azimuth_deg	float	Solar azimuth in degrees, clockwise from image top (see warning).	required
position	str	“upper right”, “upper left”, “lower right”, “lower left”.	'upper right'
length	float	Arrow length as a fraction of the axes (default 0.12).	0.12
color	str	Outer circle and arrow color.	'yellow'
inner_color	str	Inner circle color (smaller, overlaid on outer).	'orange'

Returns

Name	Type	Description
ax	matplotlib.axes.Axes

[source]

imshow_gray

plotting.imshow_gray(
    image,
    stretch='1,99',
    title=None,
    ax=None,
    **imshow_kwargs,
)

Display a grayscale image with optional percentile stretch.

Parameters

Name	Type	Description	Default
image	2D array	Image data.	required
stretch	str or None	Percentile stretch as “lo,hi” (e.g. “1,99”). Use None or “none” to disable.	'1,99'
title	str	Plot title.	None
ax	matplotlib.axes.Axes	Axes to plot on. Created if not provided.	None
**imshow_kwargs		Passed to ax.imshow().	{}

Returns

Name	Type	Description
ax	matplotlib.axes.Axes

[source]

imshow_with_sun

plotting.imshow_with_sun(
    image,
    sun_azimuth_deg,
    title=None,
    ax=None,
    stretch='1,99',
    sun_position='upper right',
    **imshow_kwargs,
)

Display a grayscale image with a sun direction indicator. Experimental.

Combines imshow_gray with add_sun_indicator (see that function’s experimental warning about the azimuth convention).

Parameters

Name	Type	Description	Default
image	2D array	Image data.	required
sun_azimuth_deg	float	Solar azimuth in degrees, clockwise from image top.	required
title	str	Plot title.	None
ax	matplotlib.axes.Axes	Axes to plot on. Created if not provided.	None
stretch	str or None	Percentile stretch (default “1,99”). None to disable.	'1,99'
sun_position	str	Indicator position: “upper right”, “upper left”, etc.	'upper right'
**imshow_kwargs		Passed to ax.imshow().	{}

Returns

Name	Type	Description
ax	matplotlib.axes.Axes

[source]

percentile_stretch

plotting.percentile_stretch(image, lo=1, hi=99)

Compute display limits from percentiles, ignoring zeros and NaN.

Parameters

Name	Type	Description	Default
image	array - like	Image data (2D or nD).	required
lo	float	Lower and upper percentile (default 1, 99).	1
hi	float	Lower and upper percentile (default 1, 99).	1

Returns

Name	Type	Description
	vmin, vmax : float	Display limits suitable for imshow(vmin=, vmax=). Returns (None, None) if no valid pixels.

[source]