使用matplotlib绘图时更改刻度标签的位置(移动) [英] change the position (move) of tick labels when plotting with matplotlib

问题描述

我正在用matplotlib密谋.代码如下(zvals具有值)

cmap = mpl.colors.ListedColormap(['darkblue', 'blue', 'lightblue','lightgreen','yellow','gold','orange','darkorange','orangered','red'])
bounds=[0, 10,20,30,40,50,60,70,80,100,200,1000]
norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
img2 = plt.imshow(zvals,interpolation='nearest',
                cmap = cmap,
                norm=norm,
                origin='lower')


xlocations = na.array(range(30)) + 0.5
xticks(xlocations, [str(x+1) for x in arange(30)], rotation=0, size=5)
gca().xaxis.set_ticks_position('none')
gca().yaxis.set_ticks_position('none')  
grid(True)

这将导致下图: http://imageshack.us/a/img145/7325/histogrammoverview.png

我想将xticks(1,2,3，..)的标签向左移动一点，使其位于相应颜色框的下方.相应地，我也想将yticks(用户1和用户2)的标签向下移动一点，以便它们正确显示.该怎么办?

事实上，我可以更改以下行 xlocations = na.array(range(30))+ 0.5 到 xlocations = na.array(range(30))

然后得到的图片是这样的: http://imageshack.us/a/img338/7325/histogrammoverview.png

请查看网格正在通过"彩色框，这不是我想要的.我希望网格如上图所示在彩色框的边缘.在此版本中，标签(1,2,3，...)正确地放置在框的下方.我如何才能正确地将标签(在彩色框下面)和一个网格放置在彩色框周围，而不是穿过彩色框的中间.

解决方案

此解决方案有效(根据答案的建议):

periods = 30
xlocations = na.array(range(periods))
xminorlocations = na.array(range(periods))+0.5
xticks(xlocations, [str(x+1) for x in arange(periods)], rotation=0, size=5)
plt.set_xticks(xminorlocations, minor=True)
grid(True, which='minor', linestyle='-')

结果:hxxp://imageshack.us/a/img9/7325/histogrammoverview.png

解决方案

我认为您可以通过

进行管理

• 将主要刻度位置设置为每个正方形的中间.
• 将次刻度设置为每个正方形的边缘.
• 将网格设置为仅在较小的刻度中显示.

使用只能在次要刻度中显示网格

plt.grid(True, which='minor')

我也将线型设置为'-'.

i am plotting with matplotlib. the code is the following (zvals has the values)

cmap = mpl.colors.ListedColormap(['darkblue', 'blue', 'lightblue','lightgreen','yellow','gold','orange','darkorange','orangered','red'])
bounds=[0, 10,20,30,40,50,60,70,80,100,200,1000]
norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
img2 = plt.imshow(zvals,interpolation='nearest',
                cmap = cmap,
                norm=norm,
                origin='lower')


xlocations = na.array(range(30)) + 0.5
xticks(xlocations, [str(x+1) for x in arange(30)], rotation=0, size=5)
gca().xaxis.set_ticks_position('none')
gca().yaxis.set_ticks_position('none')  
grid(True)

this results in the following picture: http://imageshack.us/a/img145/7325/histogrammoverview.png

i would like to move the labels of the xticks (1,2,3,..) to the left a bit, so they are underneath the corresponding color boxes. correspondingly i would also like to move the labels of the yticks (user1 and user2) down a bit so they are displayed correctly. how can this be done?

EDIT: as a matter of fact i could change the following line xlocations = na.array(range(30)) + 0.5 to xlocations = na.array(range(30))

then the resulting pictures is like this: http://imageshack.us/a/img338/7325/histogrammoverview.png

please see that the grid is going "through" the colored boxes, which is not what i want. i'd like the grid to edge the colored boxes as in the above picture. in this version though the labels (1,2,3,...) are placed correctly underneath the boxes. how can i have correctly places labels (underneath the colored boxes) and a grid which is around the colored boxes and not through the middle of the colored boxes.

SOLUTION

this solution works (as suggested by the answer):

periods = 30
xlocations = na.array(range(periods))
xminorlocations = na.array(range(periods))+0.5
xticks(xlocations, [str(x+1) for x in arange(periods)], rotation=0, size=5)
plt.set_xticks(xminorlocations, minor=True)
grid(True, which='minor', linestyle='-')

result: hxxp://imageshack.us/a/img9/7325/histogrammoverview.png

解决方案

I think that you can manage that by

• Setting the major tick locations to the middle of each square.
• Setting the minor ticks to the edges of each square.
• Setting the grid to show only in the minor ticks.

The grid can be showed only in the minor ticks using

plt.grid(True, which='minor')

I would set the line style to '-' too.

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