subplots, how to set the xlabel and xlim, but removing axis

Question

I'd like to plot EEG data and get this result:

But I am stuck on how to display the x axis label and its xlim.

After reading other questions, which use set_visible(False), I cannot resolve my issue.

I write my code in order to be reproducible:

sfreq = 256
raw_data = np.random.rand(14, 1000 * sfreq)

duration = 10 # duration of the signal
start = 200 * sfreq
final = start + int(sfreq * duration)  

channels = list(np.arange(1, len(channels) + 1 ))

fig, ax = plt.subplots(len(channels), 1, sharex=True, figsize=(10, 10))
for idx, node in enumerate(channels):
    data = raw_data[idx, start:final]
    times = np.arange(1, data.size + 1) / sfreq
    ax[idx].plot(times, data, lw=1., ls='-', c='k')
    
    ax[idx].axis('off') # to remove bounding subplot    
    ax[idx].set_yticks([]) # to remove values from y axis   
    ax[idx].text(-1, 0, node, fontsize=12) # write text
    

# plt.axis(True)
# plt.axes().get_xaxis().set_visible(True)
# plt.xlim([200, 220])
plt.xlabel('Time (seconds)', fontsize=12)
plt.tight_layout()
plt.show()

This is my result:

But I'd like this:

user_12046409 · Answer

Here are some possible changes to the plot:

make the code more python by using zip instead of an index in the for loop
change the visibility of the "spines" (the lines surrounding the subplot) instead of use axis('off')
remove the padding (margins)
use the axes transform to position the text of the y-axis
...

import matplotlib.pyplot as plt
import numpy as np

sfreq = 256
raw_data = np.random.rand(14, 1000 * sfreq)

duration = 10  # duration of the signal
start = 200 * sfreq
final = start + int(sfreq * duration)

channels = np.arange(len(raw_data)) + 1

fig, axs = plt.subplots(len(channels), 1, sharex=True, figsize=(10, 10))
for ax, node, data in zip(axs, channels, raw_data):
    data = data[start:final]
    times = np.arange(1, data.size + 1) / sfreq
    ax.plot(times, data, lw=1., ls='-', c='k')

    ax.set_yticks([])  # remove y ticks
    for sp in ax.spines:
        ax.spines[sp].set_visible(False)  # hide the 4 lines surrounding the subplot
    ax.text(-0.01, 0.5, node, fontsize=12, ha='right', va='center', transform=ax.transAxes)  # write text
    ax.margins(x=0) # avoid the empty space left and right
    if ax != axs[-1]:
        # ax.tick_params(axis='x', length=0)  # hide the tick marks
        ax.tick_params(bottom=False)  # no tick marks at the bottom

axs[-1].set_xlabel('Time (seconds)', fontsize=12, labelpad=-10) # use negative padding to get closer to the xaxis
axs[-1].set_xticks([0, duration])
axs[-1].set_xticklabels([start // sfreq, final // sfreq])
axs[-1].spines['bottom'].set_bounds([0, duration])  # only draw the spine between the two ticks
axs[-1].spines['bottom'].set_visible(True)
axs[-1].spines['bottom'].set_linewidth(2)
plt.tight_layout()
plt.show()

subplots, how to set the xlabel and xlim, but removing axis

1 Answers