如何更改所选散点图点的不透明度答案

【问题标题】：How to change the opacity of chosen scatter plot points如何更改所选散点图点的不透明度
【发布时间】：2020-03-26 22:13:53
【问题描述】：

我想创建一个交互式散点图，这样用户就可以用光标选择点，所以选择的点会突出显示，其余的点会淡化。现在它只有在颜色改变时才有效，我怎样才能改变不透明度并保持原来的颜色？

import numpy as np
from numpy.random import rand
from matplotlib.widgets import LassoSelector
from matplotlib.path import Path
import matplotlib.pyplot as plt


class SelectFromCollection(object):
    def __init__(self, ax, collection,c, alpha_other=0.3):
    self.canvas = ax.figure.canvas
    self.collection = collection
    self.alpha_other = alpha_other

    self.xys = collection.get_offsets()
    self.Npts = len(self.xys)
    self.c = c

    # Ensure that we have separate colors for each object
    self.fc = collection.get_facecolors()
    if len(self.fc) == 0:
        raise ValueError('Collection must have a facecolor')
    elif len(self.fc) == 1:
        self.fc = np.tile(self.fc, (self.Npts, 1))
    self.lasso = LassoSelector(ax, onselect=self.onselect)
    self.ind = []

def onselect(self, verts):
    path = Path(verts)
    self.ind = np.nonzero(path.contains_points(self.xys))[0]
    self.fc[:, -1] = self.alpha_other
    self.fc[self.ind, -1] = 1
    self.collection.set_facecolors(self.fc)
    self.canvas.draw_idle()

def disconnect(self):
    self.lasso.disconnect_events()
    self.fc[:, -1] = 1
    self.collection.set_facecolors(self.fc)
    self.canvas.draw_idle()


np.random.seed(1)
x, y, c = rand(3, 100)
subplot_kw = dict(xlim=(0, 1), ylim=(0, 1), autoscale_on=False)
fig, ax = plt.subplots(subplot_kw=subplot_kw)
pts = ax.scatter(x, y,c=c, s=100)
selector = SelectFromCollection(ax, pts, c)
plt.show()

【问题讨论】：

标签： python-3.x user-interface matplotlib scatter-plot

【解决方案1】：

已解决，我使用 self.collection.get_facecolors() 方法来获取格式和值，然后我只是更改了所选索引的第 3 列的值，如下所示：

fc = self.collection.get_facecolors()
fc[self.ind, 3] = 1
fc[others, 3] = self.alpha_other
self.collection.set_facecolors(fc)

干杯

【讨论】：