Adjust space between two axes while keeping it constant on other axes

For some reason I couldn't find information on this (I'm pretty sure it exists somewhere), but in the following generic example, I would like to reduce the hspace between ax1 and ax2 while keeping the same hspace between ax2-ax3 and ax3-ax4.

I'd also appreciate any links to an example like that!

import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec


def annotate_axes(fig):
    for i, ax in enumerate(fig.axes):
        ax.text(0.5, 0.5, "ax%d" % (i+1), va="center", ha="center")
        ax.tick_params(labelbottom=False, labelleft=False)

fig = plt.figure()

gs1 = GridSpec(6, 1, hspace=0.2)
ax1 = fig.add_subplot(gs1[0])
ax2 = fig.add_subplot(gs1[1])

ax3 = fig.add_subplot(gs1[2:4])
ax4 = fig.add_subplot(gs1[4:6])

annotate_axes(fig)
plt.show()

One way that might suit your need is to create a subgrid (in this example, putting hspace to 0):

import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec


def annotate_axes(fig):
    for i, ax in enumerate(fig.axes):
        ax.text(0.5, 0.5, "ax%d" % (i+1), va="center", ha="center")
        ax.tick_params(labelbottom=False, labelleft=False)

fig = plt.figure()

gs1 = GridSpec(6, 1, hspace=0.2)

# subgrid for the first two slots
# in this example with no space
subg = gs1[0:2].subgridspec(2, 1, hspace = 0)

# note the ax1 and ax2 being created from the subgrid
ax1 = fig.add_subplot(subg[0])
ax2 = fig.add_subplot(subg[1])

ax3 = fig.add_subplot(gs1[2:4])
ax4 = fig.add_subplot(gs1[4:6])

annotate_axes(fig)
plt.show()