python-3.x - 在循环中使用颜色图（python）

Question

如何编辑#ax5 和#ax6 下的for 循环以相同方式绘制图形？现在，与上图相反，下图没有颜色过渡。增加dpi后，下图出现颜色过渡，但也出现了一些不需要的东西。有没有剥落问题？谢谢

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.gridspec import GridSpec
import math
fig, ax = plt.subplots()
plt.rcParams["figure.figsize"] = [8, 8]

# Function for plotting parallels to curves
def get_parallels(length=.1):
    
    px, py = [], []
    
    for idx in range(len(x)-1):
        x0, y0, xa, ya = x[idx], y[idx], x[idx+1], y[idx+1]
        dx, dy = xa-x0, ya-y0
        norm = math.hypot(dx, dy) * 1/length
        dx /= norm
        dy /= norm        
        px.append(x0-dy)
        py.append(y0+dx)
    return px, py

def offset(x,y, o):
    """ Offset coordinates given by array x,y by o """
    X = np.c_[x,y].T
    m = np.array([[0,-1],[1,0]])
    R = np.zeros_like(X)
    S = X[:,2:]-X[:,:-2]
    R[:,1:-1] = np.dot(m, S)
    R[:,0] = np.dot(m, X[:,1]-X[:,0])
    R[:,-1] = np.dot(m, X[:,-1]-X[:,-2])
    On = R/np.sqrt(R[0,:]**2+R[1,:]**2)*o
    Out = On+X
    return Out[0,:], Out[1,:]

dpi = 20

def offset_curve(ax, x,y, o):
    """ Offset array x,y in data coordinates
        by o in points """
    trans = ax.transData.transform
    inv = ax.transData.inverted().transform
    X = np.c_[x,y]
    Xt = trans(X)
    xto, yto = offset(Xt[:,0],Xt[:,1],o*dpi/72. )
    Xto = np.c_[xto, yto]
    Xo = inv(Xto)
    return Xo[:,0], Xo[:,1]


fig = plt.figure(constrained_layout=True)

gs = GridSpec(3, 6, figure=fig)
ax5 = fig.add_subplot(gs[1, 3:6])
ax6 = fig.add_subplot(gs[2, :3])
ax7 = fig.add_subplot(gs[2, 3:6])

cmap = plt.get_cmap('Greys_r')

# ax5
x = np.linspace(-1, 1, 100)
y = -x**2
ax5.set_ylim(-1.02, 0.3)
width_l = ax5.get_ylim()[1] - ax5.get_ylim()[0]
for t in np.linspace(0, 1, 40): 
    length =  -0.1*width_l*t
    ax5.plot(*get_parallels(length=length), color=cmap(t/2 + 0.25))

# ax6
x = np.linspace(-3, 3, 100)
y = -(1/4*x**4 - 1.6*x**2) 
ax6.plot(x, y)
ax6.set_xlim(ax6.get_xlim()[0]-0.5, ax6.get_xlim()[1]+0.5)
ax6.scatter(1/2*(ax6.get_xlim()[0] + ax6.get_xlim()[1]), 1.2, marker = 'o', s=900, facecolors='none')
lines = []
width_l = ax6.get_ylim()[1] - ax6.get_ylim()[0]
for t in np.linspace(0, 1, 40):
    l, = ax6.plot(x, y - t * 0.1 * width_l, color=cmap(t/2 + 0.25))
    lines.append(l)

def plot_rainbow(event=None):
    x0 = x
    y0 = y
    for i in range(len(lines)):
        xx, yy = offset_curve(ax, x0, y0, -width_l)
        lines[i].set_data(xx, yy)
        lines[i].set_linewidth(1.1*width_l)
        x0 = xx
        y0 = yy

plot_rainbow()
fig.canvas.mpl_connect("resize_event", plot_rainbow)
fig.canvas.mpl_connect("button_release_event", plot_rainbow)
plt.savefig('fig.pdf')

标签： python-3.xmatplotlib