Colorbar for the subplots in PyGMT

Q&A PyGMT Q&A
1

Hey everyone,
I am new to PyGMT and I am trying to create subplots in PyGMT. I’ve set the colorbar position to be in the bottom center, however, it doesn’t run like that.

I have the following code so far:

import pygmt

path = r'E:\day'

fig = pygmt.Figure()

lowest = 255
highest = 325
interval = (highest - lowest) / 64

pygmt.makecpt(cmap="jet", series=[lowest, highest, interval])

with pygmt.config(FONT_TITLE="18p,5", MAP_TITLE_OFFSET="-12p", MAP_FRAME_TYPE="plain"):

    with fig.subplot(
        nrows=4,
        ncols=6,
        figsize=("42c", "28c"),
        margins=["0.2c", "0.2c"],
    ):
        for i in range(0, 24):
            fig.grdimage(
                grid=fr'{path}\2013276_{str(i).zfill(2)}.tif',
                frame=[f"lbtr+t{str(i).zfill(2)}:00"],
                cmap=True,
                panel=True,
                #dpi=300,
            )

with pygmt.config(FONT="18p,4"):
    fig.colorbar(position="JBC+w10c/0.5c+h", frame=["a10f10", "y+lLST (K)"])

fig.show()

temperature_small
temperature_small4969×3639 833 KB

One more question, how to set the colorbar annotation to show only the minimum and maximum values? The final result I would like to get is shown below.

temperature1_small
temperature1_small4969×3639 814 KB

2

Hello @wensentry,

Welcome to the GMT forum :slight_smile:!

Your issue was recognized and reported in this GitHub comment https://github.com/GenericMappingTools/pygmt/pull/2354#discussion_r1136518891
and is fixed via PR https://github.com/GenericMappingTools/pygmt/pull/2427.

So, upon PyGMT v0.10.0 placing a colorbar after an existing subplot will work correctly.

For now, you have to use +ooffset_x/offset_y to move your colorbar to the desired position:

with pygmt.config(FONT="18p,4"):
    fig.colorbar(position="JBC+o13.5c/0.5c+w10c/0.5c+h", frame=["a10f10", "y+lLST (K)"])
1 Like
3

Actually, the PR was merged into PyGMT v0.9.0. So if you upgrade your PyGMT to v0.9.0, you should get the expected results.

4

Hello @seisman it works!!!, thank you!!, stay safe and best regards.

6

Hello @yvonnefroehlich Thank you so much for your help. I have one more question. How to set the colorbar annotation to show only the minimum and maximum values? The final result I would like to get is shown below.

temperature1_small
temperature1_small4969×3639 814 KB

1 Like
7

@seisman, you are completely right! I am sorry for mixing this up :slightly_frowning_face:.

8

So far, I know unfortunately no direct way to add only the minimum and maximum values as colorbar annotations.

One (inelegant) idea or workaround here is to plot the same colorbar twice:

import pygmt


size = 5

fig = pygmt.Figure()

lowest = 255
highest = 325
interval = (highest - lowest) / 64
pygmt.makecpt(cmap="jet", series=[lowest, highest, interval])

with fig.subplot(
    nrows=4,
    ncols=6,
    figsize=("42c", "28c"),
    margins=["0.2c", "0.2c"],
):
    for i in range(0, 24):
        fig.basemap(
            region=[-size, size, -size, size],
            projection="X?",
            frame="lbtr",
            panel=True,
        )
    
# Add annotation for lowest value
fig.colorbar(
    cmap=True,
    position="JBC+w10c/0.5c+h", 
    frame=["a" + str(lowest), "y+lLST (K)"],
)
# Add annotation for highest value
fig.colorbar(
    cmap=True,
    position="JBC+w10c/0.5c+h", 
    frame=["a" + str(highest), "y+lLST (K)"],
)

fig.show()
# fig.savefig(fname="colorbar_anno_min_max.png")

Output figure:

colorbar_anno_min_max
colorbar_anno_min_max4972×3543 62.9 KB

1 Like
9

@yvonnefroehlich, Thank you so much. I learned a lot from you. Appreciate your time and help.

10

If interested, build GMT from this branch and try -S+r to limit annotations to the lower and upper boundaries.

11

Now merged into master.

14

@pwessel, thank you so much.