The color parameter of plot and plot3d methods can be 1d array

[core-man]

Description of the problem

We need to update the documentation for the color parameter in plot and plot3d because color can also be 1d array (originally posted in https://github.com/GenericMappingTools/pygmt/pull/1065#issuecomment-801212175).

---

See the description of the color parameter of plot:

color (str) – Select color or pattern for filling of symbols or polygons. Default is no fill.

See the description of the color parameter of plot3d:

color (str) – Select color or pattern for filling of symbols or polygons. Default is no fill.

---

However, color can also be a 1d array just like the sizes parameter when we use x/y parameters for in the plot and plot3d methods. See the last example in Plotting data points. We can set color=data.depth_km and data.depth_km is a 1d array.

import pygmt
data = pygmt.datasets.load_japan_quakes()
region = [
    data.longitude.min() - 1,
    data.longitude.max() + 1,
    data.latitude.min() - 1,
    data.latitude.max() + 1,
]
print(region)
print(data.head())

fig = pygmt.Figure()
fig.basemap(region=region, projection="M15c", frame=True)
fig.coast(land="black", water="skyblue")
pygmt.makecpt(cmap="viridis", series=[data.depth_km.min(), data.depth_km.max()])
fig.plot(
    x=data.longitude,
    y=data.latitude,
    sizes=0.02 * 2 ** data.magnitude,
    color=data.depth_km,
    cmap=True,
    style="cc",
    pen="black",
)
fig.colorbar(frame='af+l"Depth (km)"')
fig.show()

[seisman]

If I understand it correctly, we only need to update the docstrings to mention that color can be a string or a 1darray?

[core-man]

If I understand it correctly, we only need to update the docstrings to mention that color can be a string or a 1darray?

I think so. May better to add an additional note (Only valid if using x/y) like the size parameter for the plot method.

sizes (1d array) – The sizes of the data points in units specified using style. Only valid if using x/y.

Because we raise GMTInvalidInput when color is used with the data parameter just like the sizes parameter.

https://github.com/GenericMappingTools/pygmt/blob/1a2289a20519a4dbf1c78543acd4a654b981811e/pygmt/src/plot.py#L207-L211

https://github.com/GenericMappingTools/pygmt/blob/1a2289a20519a4dbf1c78543acd4a654b981811e/pygmt/src/plot.py#L214-L218

[seisman]

Sounds good. Maybe also need to mention that cmap is required if color is a 1darray (I don't check if it's true).

[core-man]

Sounds good. Maybe also need to mention that cmap is required if color is a 1darray (I don't check if it's true).

I think so. See GMT plot:

where the optional z is required when -C is used

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@seisman I use the above Plot data points code but remove cmap=True. Cannot plot the symbols. So you are right.

[seisman]

@core-man This issue looks easy to fix. Do you want to work on it?

[core-man]

@core-man This issue looks easy to fix. Do you want to work on it?

So we don't want to leave it to new contributors?

[seisman]

So we don't want to leave it to new contributors?

The description of the issue is so long that people may be lost about what they should do.

You may either submit a quick fix or give more details about the expected changes.