python - Matplotlib : the colorbar keeps shrinking

Question

我编写了一个代码，其中有一个名为 array2 的数组，其中包含 0. 和 1. 之间的数字。当我单击 imshow 显示的数组时，数组中的单元格的值为 2. 并变为红色。

然后我添加了一个颜色条，但单击它后它不断缩小，并且单元格没有变成红色。

我做错了什么？

没有颜色条的代码(工作正常)

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
from matplotlib import cm
from mpl_toolkits.axes_grid1 import make_axes_locatable
from random import random


def test(n):
    array1 = np.zeros((n,n))
    for i in range(n):
        for j in range(n):
            array1[i,j] = random()
    return array1


# Array
global array2
array2 = test(10)


# Colormap
greens = cm.Greens(np.linspace(0,1, num=50))
greensfill = cm.Greens(np.ones(25))
red = [(1,0,0,1)]*len(greens)
gray = [(.5,.5,.5,1)]*len(greens)
colors = np.vstack((greens, greensfill, red, gray))
mycmap = mcolors.LinearSegmentedColormap.from_list('my_colormap', colors)


# Matplotlib
fig, axes = plt.subplots(1)
fig.tight_layout()

plt.imshow(array2, animated=True, cmap = mycmap, interpolation="none", vmin=0, vmax=3.5, origin='lower')


def onclick(event):
    global x, y
    x, y = int(event.xdata), int(event.ydata)
    array2[y,x] = 2.

    plt.imshow(array2, animated=True, cmap = mycmap, interpolation="none", vmin=0, vmax=3.5, origin='lower')


fig.canvas.mpl_connect('button_press_event', onclick)

带有颜色条的代码(不起作用)

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
from matplotlib import cm
from mpl_toolkits.axes_grid1 import make_axes_locatable
from random import random 


def test(n):
    array1 = np.zeros((n,n))
    for i in range(n):
        for j in range(n):
            array1[i,j] = random()
    return array1


# Array
global array2
array2 = test(10)


# Colormap
greens = cm.Greens(np.linspace(0,1, num=50))
greensfill = cm.Greens(np.ones(25))
red = [(1,0,0,1)]*len(greens)
gray = [(.5,.5,.5,1)]*len(greens)
colors = np.vstack((greens, greensfill, red, gray))
mycmap = mcolors.LinearSegmentedColormap.from_list('my_colormap', colors)


# Matplotlib
fig, axes = plt.subplots(1)
fig.tight_layout()

im = plt.imshow(array2, animated=True, cmap = mycmap, interpolation="none", vmin=0, vmax=3.5, origin='lower')

divider = make_axes_locatable(axes)
cax = divider.append_axes("right", size="13%", pad=0.2)

cb = plt.colorbar(im, cax=cax, boundaries=np.linspace(0,1, num=100), ticks=[0,1])

cb.set_label("Title", fontsize=15, labelpad=-5, y=0.5)

def onclick(event):
    global x, y
    x, y = int(event.xdata), int(event.ydata)
    array2[y,x] = 2.

    im = plt.imshow(array2, animated=True, cmap = mycmap, interpolation="none", vmin=0, vmax=3.5, origin='lower')

    divider = make_axes_locatable(axes)
    cax = divider.append_axes("right", size="13%", pad=0.2)

    cb = plt.colorbar(im, cax=cax, boundaries=np.linspace(0,1, num=100), ticks=[0,1])

    cb.set_label("Title", fontsize=15, labelpad=-5, y=0.5)  


fig.canvas.mpl_connect('button_press_event', onclick)

Answer 1

最好只更新 imshow，而不是每次执行单击时都绘制一个新的。这可以使用 .set_data() 方法来完成。优点是颜色条可以留在原处并且​​不会被触摸。

一般来说，在进行交互式操作时，最好直接使用绘图对象而不是 pyplot。因此，在大多数情况下，使用 fig 和 ax 而不是 plt。

请注意，要准确捕获像素上的点击，您需要先对坐标进行舍入，int(np.round(event.xdata))。

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

global array2
array2 = np.random.rand(10,10)

# Colormap
greens = cm.Greens(np.linspace(0,1, num=50))
greensfill = cm.Greens(np.ones(25))
red = [(1,0,0,1)]*len(greens)
gray = [(.5,.5,.5,1)]*len(greens)
colors = np.vstack((greens, greensfill, red, gray))
mycmap = mcolors.LinearSegmentedColormap.from_list('my_colormap', colors)

# Matplotlib
fig, ax = plt.subplots()
fig.tight_layout()
im = ax.imshow(array2, animated=True, cmap = mycmap, interpolation="none", 
               vmin=0, vmax=3.5, origin='lower')

divider = make_axes_locatable(ax)
cax = divider.append_axes("right", size="13%", pad=0.2)
cb = fig.colorbar(im, ax =ax, cax=cax, boundaries=np.linspace(0,1, num=100), 
                  ticks=[0,1])
cb.set_label("Title", fontsize=15, labelpad=-5, y=0.5)

def onclick(event):
    x, y = int(np.round(event.xdata)), int(np.round(event.ydata))
    array2[y,x] = 2.
    im.set_data(array2)
    fig.canvas.draw_idle()  

fig.canvas.mpl_connect('button_press_event', onclick)
plt.show()