如何用imshow（）限制x軸的範圍？

Question

我有以下數據

1.105 0.919 0.842 0.715 0.704 0.752 0.827 1.049 0.584 
0.998 0.931 0.816 0.787 0.803 0.856 0.782 0.872 0.710 
1.268 1.189 1.036 0.984 0.847 0.948 1.083 0.864 0.792 

，我與imshow()

結果繪製如下：

這裏是我的代碼：

from numpy import* 
import matplotlib.cm as cm 
import matplotlib.mlab as mlab 
import matplotlib.pyplot as plt 
from mpl_toolkits.axes_grid1 import make_axes_locatable 

shape=(3,9) 
velocity=zeros(shape) 


fig = plt.figure(figsize=(16, 12), dpi=100) 
ax1 = fig.add_subplot(111,aspect='equal') 
# ax1.set_yticks([int(100*j) for j in range(0,4)]) 
ax1.set_yticks([int(j) for j in range(0,4)]) 
ax1.set_xticks([int(j) for j in range(-4,5)]) 
for label in ax1.get_xticklabels() + ax1.get_yticklabels(): 
    label.set_fontsize(15) 
for tick in ax1.get_xticklines() + ax1.get_yticklines(): 
    tick.set_markeredgewidth(2) 
    tick.set_markersize(6) 
ax1.set_aspect("equal") 
velocity=loadtxt("fieldvelocitybot-300-100-100_400.dat") 

im = plt.imshow(velocity, cmap=cm.jet, interpolation='nearest',origin='lower',vmin=0,vmax=1.7, extent=[-4.50,4.50,0.,3.00]) 

divider = make_axes_locatable(ax1) 
cax = divider.append_axes("right", size="2.5%", pad=0.3) 
cb=plt.colorbar(im,cax=cax) 
cb.set_label('Speed [$m/s$]') 
plt.savefig("speed_400.png") 
plt.close(fig) 

我的問題是：如何顯示從-4到4的結果？直覺上我想到改變extent=[-4.00,4.00,0.,3.00]，但是軸線剛剛移位。結果是這樣的：

Answer 1

設置imshow的範圍很好，因爲它定義了數據的範圍。它不指定所顯示的範圍，因爲這是軸的特性，並且可以通過簡單地增加ax1.set_xlim（-4,4）

所以設置：

from mpl_toolkits.axes_grid1 import make_axes_locatable 
import numpy as np 
import matplotlib.pyplot as plt 

velocity=np.random.rand(3,9) 

fig, ax1 = plt.subplots(1,1,figsize=(16, 12), dpi=100, subplot_kw={'aspect': 'equal'}) 

ax1.set_yticks([int(j) for j in range(0,4)]) 
ax1.set_xticks([int(j) for j in range(-4,5)]) 

for label in ax1.get_xticklabels() + ax1.get_yticklabels(): 
    label.set_fontsize(15) 
for tick in ax1.get_xticklines() + ax1.get_yticklines(): 
    tick.set_markeredgewidth(2) 
    tick.set_markersize(6) 

im = ax1.imshow(velocity, cmap=cm.jet,  interpolation='nearest',origin='lower',vmin=0,vmax=1.7, extent=[-4.50,4.50,0,3]) 
ax1.set_xlim(-4,4) 

divider = make_axes_locatable(ax1) 
cax = divider.append_axes("right", size="2.5%", pad=0.3) 
cb=plt.colorbar(im,cax=cax) 
cb.set_label('Speed [$m/s$]') 

plt.savefig("speed_400.png") 
plt.close(fig)