Add support for ImageStack

[ahuang11]

Closes #691

import numpy as np
import geoviews as gv
import holoviews as hv
import cartopy.crs as ccrs

hv.extension("bokeh")

x = np.arange(-120, -117)
y = np.arange(40, 43)
a = np.array([[np.nan, np.nan, 1], [np.nan, np.nan, 1], [np.nan] * 3])
b = np.array([[np.nan] * 3, [1, 1, 1], [np.nan] * 3])

img_stack = gv.ImageStack(
    (x, y, a, b), kdims=["x", "y"], vdims=["a", "b"], crs=ccrs.PlateCarree()
).opts(cmap=["red", "blue"])

gv.feature.coastline() * img_stack

[ahuang11]

Weird thing is in MPL, the data is flipped vertically:

import numpy as np
import geoviews as gv
import holoviews as hv
import cartopy.crs as ccrs

hv.extension("matplotlib")

x = np.arange(-120, -117)
y = np.arange(40, 43)
a = np.array([[np.nan, np.nan, 1], [np.nan, np.nan, 1], [np.nan] * 3])
b = np.array([[np.nan] * 3, [1, 1, 1], [np.nan] * 3])

img_stack = gv.ImageStack(
    (x, y, a, b), kdims=["x", "y"], vdims=["a", "b"], crs=ccrs.PlateCarree()
).opts(cmap=["red", "blue"], xlim=(-122.2, -110), ylim=(39, 42))

gv.feature.coastline() * img_stack

Seems to be only an issue in ImageStack, gv.Image looks fine:

hv.ImageStack also looks fine.

[ahuang11]

I have no idea why MPL ImageStack is not going through this code; if I add print/raise, it doesn't do anything.

[ahuang11]

I am so stumped on how this works:

import numpy as np
import geoviews as gv
import cartopy.crs as ccrs
import panel as pn

gv.extension("matplotlib")

x = np.arange(-120, -117)
y = np.arange(40, 43)
a = np.array([[np.nan, np.nan, 1], [np.nan, np.nan, 1], [np.nan] * 3])
b = np.array([[np.nan] * 3, [1, 1, 1], [np.nan] * 3])

img_stack = gv.ImageStack(
    (x, y, a, b), kdims=["x", "y"], vdims=["a", "b"], crs=ccrs.PlateCarree()
)

img_stack

when I have raise sprinkled all across its methods.

[hoxbro]

Can you test if this works with non-equal lengths of x and y?

[ahuang11]

Can you test if this works with non-equal lengths of x and y?

Like this?

import numpy as np
import geoviews as gv
import holoviews as hv
import cartopy.crs as ccrs

hv.extension("bokeh")

x = np.arange(-120, -115)
y = np.arange(40, 43)
a = np.random.rand(len(y), len(x))
b = np.random.rand(len(y), len(x))

img_stack = gv.ImageStack(
    (x, y, a, b), kdims=["x", "y"], vdims=["a", "b"], crs=ccrs.PlateCarree()
).opts(cmap=["red", "blue"], xlim=(-122.2, -110), ylim=(39, 42))

gv.feature.coastline() * img_stack