How to add gridlines between each GridSpec subplot

Question

I have a matplotlib gridspec plot as below:

import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

fig2 = plt.figure(figsize=[8,8])
spec2 = gridspec.GridSpec(ncols=2, nrows=2, figure=fig2)
f2_ax1 = fig2.add_subplot(spec2[0, 0])
f2_ax2 = fig2.add_subplot(spec2[0, 1])
f2_ax3 = fig2.add_subplot(spec2[1, 0])
f2_ax4 = fig2.add_subplot(spec2[1, 1])

I want to add gridlines for the above plot. I'm not able to do that with hlines as gridpec attribute has no object hlines.

Is it possible to add gridlines for gridspec object in matplotlib as below:

https://discourse.matplotlib.org/t/horizontal-and-vertical-lines-between-subplots/13540 this might be helpful — S P Sharan, Jan 04 '22 at 15:21

score 0 · Answer 1 · answered Jan 04 '22 at 16:05

0

This is a bit complicated, but the following solution takes into account decorations on the axes (note how the grid goes below the xlabel). You could probably simplify if you know exactly where your axes are going to be:

import matplotlib.pyplot as plt
import numpy as np
import matplotlib as mpl

fig, axs = plt.subplots(2, 2, constrained_layout=True)

axs[0, 0].set_xlabel('Boo')
fig.draw_without_rendering()

trans = fig.transFigure

# line after the first column:
right = 0
for a in axs[:, 0]:
    bb = trans.inverted().transform_bbox(a.get_tightbbox(renderer=fig.canvas.get_renderer()))
    right = max(right, bb.x1)
right = right + 0.01
fig.add_artist(mpl.lines.Line2D([right, right], [0, 1], linestyle='--'))

# line after first row
bottom = 1
for a in axs[0, :]:
    bb = trans.inverted().transform_bbox(a.get_tightbbox(renderer=fig.canvas.get_renderer()))
    bottom = min(bottom, bb.y0)
bottom = bottom - 0.01
fig.add_artist(mpl.lines.Line2D([0, 1], [bottom, bottom], linestyle='--'), )
plt.show()

answered Jan 04 '22 at 16:05

Jody Klymak

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I'm using `spec = gridspec.GridSpec(ncols=2, nrows=2, figure=fig)` instead of `fig, axs = plt.subplots(2, 2, constrained_layout=True)`. How to get the `axs` in gridspec? – Ailurophile Jan 04 '22 at 16:09
use `f2_ax1` etc instead of `axs[..,..]`. – Jody Klymak Jan 04 '22 at 16:21
But using gridspec and a bunch of `add_subplot` calls is not very idiomatic... – Jody Klymak Jan 04 '22 at 16:21
Actually, in my case, I'm adding plot/figure in for loop to single plot using `gridspec` – Ailurophile Jan 04 '22 at 16:25
Like [here](https://stackoverflow.com/q/70574478/14045537) – Ailurophile Jan 04 '22 at 16:25
Error `AttributeError: 'Figure' object has no attribute 'draw_without_rendering'` – Ailurophile Jan 04 '22 at 16:28
You have an older version of Matplotlib. You can try `fig.canvas.draw()`. As for your loop, that is more easily done as I have suggested above - instead of passing `fig.add_subplot(gs[0, 0])` to your plotting routine, pass `axs[0, 0]`. – Jody Klymak Jan 04 '22 at 16:30
or if you are copying that other code exactly pass `axs.flat[i]` – Jody Klymak Jan 04 '22 at 16:37
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/240757/discussion-between-pluviophile-and-jody-klymak). – Ailurophile Jan 05 '22 at 13:52

How to add gridlines between each GridSpec subplot

1 Answers1