堆积条形图 - y轴和第一个条形之间的空间：matplotlib.pyplot

Question

I am just starting out with matplotlib.pyplot and am a little stuck.

Using the example in the matpltlib.pyplot documentation, I have created a stacked bar chart using the following code:

import numpy as np
import matplotlib.pyplot as plt

N = 7
OECD = (242, 244, 255, 263, 269, 276, 285)
NonOECD = (282, 328, 375, 417, 460, 501, 535)
Sum = ('524', '572', '630', '680', '729', '777', '820')
ind = np.arange(N)
width = 0.5

p1 = plt.bar(ind, NonOECD, width, color = 'r')
p2 = plt.bar(ind, OECD, width, color = 'b', bottom = NonOECD)

plt.ylabel('Quadrillion Btu')
plt.title('World Total Energy Consumption 2010 - 2040')
plt.xticks(ind+width/2., ('2010', '2015', '2020', '2025', '2030', '2035', '2040'))
plt.yticks(np.arange(0, 1001, 200))
plt.legend((p1[0], p2[0]), ('Non - OECD', 'OECD'), loc = 2, frameon = 'false')
plt.tick_params(top = 'off', bottom = 'off', right = 'off')
plt.grid(axis = 'y', linestyle = '-')

plt.show()

However, I would prefer it if the first bar (2010) is not right up against the y-axis.
I have tried simply adding 1 to ind in both of plt1 and plt2
ie

p1 = plt.bar(ind+1, NonOECD, width, color = 'r')  
p2 = plt.bar(ind+1, OECD, width, color = 'b', bottom = NonOECD)

But, I am unable to work out the equivalent change for the ticklabels. So, thus far, all I produce is:

Having said that, I can fudge this by making N = 8, adding an additional zero first term in both the tuples? OECD and NonOECD and adding a blank xticklabel:
ie

N = 8  
OECD = (0, 242, 244, 255, 263, 269, 276, 285)  
NonOECD = (0, 282, 328, 375, 417, 460, 501, 535)  
Sum = (0, '524', '572', '630', '680', '729', '777', '820')  

plt.xticks(ind+width/2., ('', '2010', '2015', '2020', '2025', '2030', '2035', 2040'))

However, I am unable to use this fudge as I want to display the totals on top of the stacks ....

Answer 1

You want to use the "margins" function. Your code modified:

fig = plt.figure()
ax  = fig.add_subplot(111)
# the first argument is the margin of the x-axis, the second of the y-axis
ax.margins(0.04, 0)  

p1 = ax.bar(ind, NonOECD, width, color = 'r')
p2 = ax.bar(ind, OECD, width, color = 'b', bottom = NonOECD)