how to set cmap colors manually?

Question

I'm using geopandas' explore and trying to change colors depending on value using cmap.

For example:

• If 0 < value <= 2 then return 'red'
• If 2 < value <= 4 then return 'green' etc.

Is it possible to do this using cmap ?

def my_colormap(value):
    if value < 2: 
        return 'red'
    else:
        return 'black'

geodata.explore("xxxx", cmap= lambda value: my_colormap(value), vmax = 8) 

Result:

ValueError: ... is not a valid value for name; supported values are 'Accent', 'Accent_r', 'Blues', 'Blues_r', 'BrBG', 'BrBG_r', 'BuGn', 'BuGn_r', 'BuPu', 'BuPu_r', 'CMRmap', 'CMRmap_r', ...

Answer 1

You can use :

import numpy as np

conditions = [
    geodata["value"].between(0, 2, inclusive="right"),
    geodata["value"].between(2, 4, inclusive="right"),
    geodata["value"].gt(4)
    # add here more conditions
]

colors = ["red", "green", "black"] # add here more colors

geodata["color"] = np.select(conditions, colors, default="black")

geodata.explore(column="color", cmap=sorted(colors), legend=True)

Output :

Input used :

np.random.seed(1)

geodata = gpd.read_file(gpd.datasets.get_path("naturalearth_lowres"))

geodata["value"] = np.random.randint(0, 10, len(geodata))