I have a NetCDF (.nc) file which contain grid-cell classified data where I have assigned values 1, 2, 3 for cells on basis of classification criteria. I plotted this using pygmt.grdimage while following basic categorical cpt provided in this palatte table link
cpt = pygmt.makecpt(cmap="categorical", series=[1,4,1], truncate=[0,3])
Is there any way I can define my own colour codes for 1, 2 and 3 valued classes using hex codes in the categorical cpt.
Hello @trivial,
welcome to the GMT forum 
!
For a categorical colormap, you can pass one string of comma-separated colors to the cmap parameter. Use the color_model parameter to give annotations for the single colors (categories).
import pygmt
size = 5
fig = pygmt.Figure()
fig.basemap(region=[-size, size] * 2, projection=f"X{size*2}c", frame=1)
# Set up categorical colormap
pygmt.makecpt(cmap="#1C1CE5,#9090E9,#0B0B7E", series=[1, 3, 1], color_model="+c1-3")
# Plot some sample data
fig.plot(x=[-2] * 3, y=[-2, 0, 2], fill=[1, 2, 3], cmap=True, style="c1c")
# Add colorbar
# Divide colorbar into equal-sized rectangles via the equalsize parameter
fig.colorbar(cmap=True, position="jMC", equalsize=0.2)
fig.show()
