Python Matplotlib 自定义缩放功能无效

Question

我正在为交互式 Mandelbrot 集显示编写代码，我希望缩放功能在每次使用时更新图像。所以我使用 Matplotlib 事件处理来创建自定义缩放功能。

已有的缩放功能会在您放大时对图像进行像素化处理，因为它会放大同一幅图像。我的缩放应该在每次拖动鼠标时更新图像。

但是没用。每次我缩放一次，图都不会改变形状，所以图像本身会拉伸。再次缩放，它只是在 原始图片 上缩放。滴答声甚至不会一直变化。试一试——这是我的代码，图片由 Trenton McKinney 提供：

# Get necessary packages
import numpy as np
from matplotlib import pyplot as plt

# Calculation
COLORS = [(1, 0, 0)]
for transition in [[0, 1, 0], [-1, 0, 0], [0, 0, 1], [0, -1, 0], [1, 0, 0]]:
    for _ in range(10):
        r, g, b = COLORS[-1]
        r = round(r + transition[0] / 10, 1)
        g = round(g + transition[1] / 10, 1)
        b = round(b + transition[2] / 10, 1)
        COLORS.append((r, g, b))
        
def color(n):
    z = complex(0, 0)
    c = n
    for n in range(len(COLORS)):
        z = z ** 2 + c
        if abs(z) > 2:
            return COLORS[n]
    return (0, 0, 0)


def get_data(c1, c2):
    d = []
    for i in np.linspace(c1.imag, c2.imag, num = 500):
        rvals = [complex(r, i) for r in np.linspace(c1.real, c2.real, num = 500)]
        d.append(list(map(color, rvals)))
    return d


# Interface
corner1 = (-2, -2)
corner2 = (2, 2)

def display_data(c1, c2):
    data = get_data(c1, c2)
    image.set_data(data)
    figure.show()
    
    
def startzoom(event):
    global corner1, corner2
    if event.button:
        x = event.xdata
        y = event.ydata
        corner1 = corner2 = (x, y)
        
        
def stopzoom(event):
    global corner1, corner2
    if event.button:
        x = event.xdata
        y = event.ydata
        corner2 = (x, y)
        if corner1 == corner2:
            corner1, corner2 = (-2, -2), (2, 2)
        display_data(complex(*corner1), complex(*corner2))
        

# Put it all together
data = get_data(complex(*corner1), complex(*corner2))
figure, axes = plt.subplots()
axes.set_title("Mandelbrot Set")
axes.set_xlabel("Real")
axes.set_ylabel("Imaginary")
image = axes.imshow(list(reversed(data)), extent = [-2, 2, -2, 2])
figure.canvas.mpl_connect("button_press_event", startzoom)
figure.canvas.mpl_connect("button_release_event", stopzoom)
figure.show()

我该怎么办？

Answer 1

我编辑了你的 display_data 函数如下：

def display_data(c1, c2):
    data = get_data(c1, c2)
    axes.imshow(list(reversed(data)), extent = [corner1[0], corner2[0], corner1[1], corner2[1]])
    plt.show()

您应该在每次用户单击绘图时更新 extent 参数值，以便更新图像边框。
此外，我添加了 axes.invert_xaxis() 和 axes.invert_yaxis() 这样缩放在每个方向都有效：从左下角到右上角，从左上角到右下角，从右上角到左下角和从右下角到左上角。

完整代码

import numpy as np
from matplotlib import pyplot as plt

# Calculation
COLORS = [(1, 0, 0)]
for transition in [[0, 1, 0], [-1, 0, 0], [0, 0, 1], [0, -1, 0], [1, 0, 0]]:
    for _ in range(10):
        r, g, b = COLORS[-1]
        r = round(r + transition[0] / 10, 1)
        g = round(g + transition[1] / 10, 1)
        b = round(b + transition[2] / 10, 1)
        COLORS.append((r, g, b))

def color(n):
    z = complex(0, 0)
    c = n
    for n in range(len(COLORS)):
        z = z ** 2 + c
        if abs(z) > 2:
            return COLORS[n]
    return (0, 0, 0)


def get_data(c1, c2):
    d = []
    for i in np.linspace(c1.imag, c2.imag, num = 500):
        rvals = [complex(r, i) for r in np.linspace(c1.real, c2.real, num = 500)]
        d.append(list(map(color, rvals)))
    return d


# Interface
corner1 = (-2, -2)
corner2 = (2, 2)


def display_data(c1, c2):
    data = get_data(c1, c2)
    axes.imshow(list(reversed(data)), extent = [corner1[0], corner2[0], corner1[1], corner2[1]])
    plt.show()


def startzoom(event):
    global corner1, corner2
    if event.button:
        x = event.xdata
        y = event.ydata
        corner1 = corner2 = (x, y)


def stopzoom(event):
    global corner1, corner2
    if event.button:
        x = event.xdata
        y = event.ydata
        corner2 = (x, y)
        if corner1 == corner2:
            corner1, corner2 = (-2, -2), (2, 2)
        display_data(complex(*corner1), complex(*corner2))


# Put it all together
data = get_data(complex(*corner1), complex(*corner2))
figure, axes = plt.subplots()
axes.set_title("Mandelbrot Set")
axes.set_xlabel("Real")
axes.set_ylabel("Imaginary")
image = axes.imshow(list(reversed(data)), extent = [-2, 2, -2, 2])
figure.canvas.mpl_connect("button_press_event", startzoom)
figure.canvas.mpl_connect("button_release_event", stopzoom)
plt.show()

Python Matplotlib 自定义缩放功能无效

Python Matplotlib custom zoom function isn't working

python

math

numpy

matplotlib

imshow

完整代码