Uneven subplot in python

No need to use gridspec here. Just add the subplots where you want to have them.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib import gridspec

# generate some data
x = np.arange(0, 10, 0.2)
y = np.sin(x)

# plot it
fig = plt.figure(figsize=(8, 6))

ax1= fig.add_subplot(3,3,1)
ax2= fig.add_subplot(3,3,2)
ax3= fig.add_subplot(3,3,4)
ax4= fig.add_subplot(3,3,5)
ax5= fig.add_subplot(3,3,7)
ax6= fig.add_subplot(3,3,8)

ax7= fig.add_subplot(2,3,3)
ax8= fig.add_subplot(2,3,6)

plt.show()

I assume your problem is with the two plots in the last row. One idea could be to think of the grid as a (3,6) grid. You use two columns for each plot in the first two rows and 3 columns for the two plots in the last row.

ax1 = plt.subplot2grid((3, 6), (0, 0), colspan=2)
ax2 = plt.subplot2grid((3, 6), (0, 2), colspan=2)
ax3 = plt.subplot2grid((3, 6), (0, 4), colspan=2)
ax4 = plt.subplot2grid((3, 6), (1, 0), colspan=2)
ax5 = plt.subplot2grid((3, 6), (1, 2), colspan=2)
ax6 = plt.subplot2grid((3, 6), (1, 4), colspan=2)
ax7 = plt.subplot2grid((3, 6), (2, 0), colspan=3)
ax8 = plt.subplot2grid((3, 6), (2, 3), colspan=3)

Provided answer as answer from the question. The following was written by OP:

Thanks @datasailor for the solution. Here is a working example:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib import gridspec

# generate some data
x = np.arange(0, 10, 0.2)
y = np.sin(x)

# plot it
fig = plt.figure(figsize=(8, 6))

gs = gridspec.GridSpec(6, 3)

ax0 = plt.subplot(gs[0:2,0])
ax0.plot(x, y)
ax1 = plt.subplot(gs[2:4,0])
ax1.plot(y, x)
ax2 = plt.subplot(gs[4:6,0])
ax2.plot(y, x)

ax3 = plt.subplot(gs[0:2,1])
ax3.plot(x, y)
ax4 = plt.subplot(gs[2:4,1])
ax4.plot(y, x)
ax5 = plt.subplot(gs[4:6,1])
ax5.plot(y, x)

ax6 = plt.subplot(gs[0:3,2])
ax6.plot(x, y)
ax7 = plt.subplot(gs[3:6,2])
ax7.plot(y, x)


plt.tight_layout()
plt.savefig('grid_figure.png')

plt.show()