Title for each subplotSpec (subplots within subplots)

Question

I want to make a plot that has 2x2 outer layout and within each one of these 2x3 layouts. I managed to get everything working using gridSpec, but I cannot seem to assign a title for each one of subplotSpec (there are 2x2 subplotSpec).

Row titles for matplotlib subplot This in principle should give me the solution, but I want to know if there are ways to achieve this using gridSpec and not hiding the white frame.

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

netdict = ["chain","V"]
sigdict = ["no","with"]

fig = plt.figure(figsize=(10, 8))
outer = gridspec.GridSpec(2, 2, wspace=0.3, hspace=0.3) # make a 2x2 outer frame

for ni, networktype in enumerate(netdict):
    for si, sigtype in enumerate(sigdict):
        fig.add_subplot(outer[ni*2+si])
        plt.title(networktype+ " " + sigtype) # title for each outer frame
        plt._frameon=False # this should make the unnecessary white frame go away
        inner = gridspec.GridSpecFromSubplotSpec(2, 3, # make 2x3 inner frame
                        subplot_spec=outer[ni*2+si], wspace=0.4, hspace=0.4)
        for ti,tau in enumerate([5.5,12.5]):
            for u, xy_delay in enumerate([0,tau,2*tau]):
                ax = plt.Subplot(fig, inner[ti*3+u])
                ax.plot(np.sin(np.linspace(0,10,0.5))
                ax.set(title=r"$\tau_u={}$".format(xy_delay))
                fig.add_subplot(ax)
plt.show()

Not without placing by hand. `gridspec.suptitle` is something matplotlib is thinking about, but its not been done yet. — Jody Klymak, May 29 '19 at 16:00

score 2 · Answer 1 · answered May 12 '20 at 13:08

Just stumbled upon this as I had to do something similar. I found an easy solution was to create another Subplot for the outer grids and simply shutting their axes off:

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

fig = plt.figure(figsize=(12, 6))
outer = gridspec.GridSpec(1, 2, wspace=0.2, hspace=0.2)

for i, layer in enumerate(layer_list):
    # create inner plots
    inner = gridspec.GridSpecFromSubplotSpec(2, 2,
                    subplot_spec=outer[i], wspace=0.1, hspace=0.1)
    # set outer titles
    ax = plt.Subplot(fig, outer[i])
    ax.set_title("Layer {}".format(layer))
    ax.axis('off')
    fig.add_subplot(ax)
    for j, filter_pos in enumerate(filter_pos_list):
        # create image plot
        ax = plt.Subplot(fig, inner[j])
        # load image
        img = ...
        ax.imshow(img)
        # set inner title
        ax.set_title("Filter {}".format(filter_pos))
        ax.set_xticks([])
        ax.set_yticks([])
        fig.add_subplot(ax)
fig.show()

thanks for this! I notice that the "Layer" title is at the same level as the "Filter" titles. Is there any way to move this a little bit higher than the real subplot titles? Basically, something like achieving a `suptitle` for the gridspec (which is not available as of now). — irene, Jul 14 '20 at 13:36

Title for each subplotSpec (subplots within subplots)

1 Answers1