How to make a colour transit

Community
1

Hi, could I ask you for your help with the following script? How to edit the for cycles under #ax5 and #ax6 to plot graphs in the same fashion? Now, the lower figure has no colour transit, as opposed to the upper one. The colour transit appears in the lower figure after increasing of dpi, however, some unwanted stuff also appears. Is there a scalling problem? Thank you

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.gridspec import GridSpec
import math

# Plot figure with size
fig, ax = plt.subplots()
plt.rcParams["figure.figsize"] = [8, 8]

def format_axes(fig):
for i, ax in enumerate(fig.axes):
    ax.tick_params(labelbottom=False, labelleft=False)

    for ax in [ax]:
        ax.set_yticks([])
        ax.set_xticks([])
# Removing axis 
    for side in ['right','top','left','bottom']:
        ax.spines[side].set_visible(False)


# 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])

# Color map
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)

# ax7
x = np.linspace(-3, 3, 100)
y = 1/4*x**4 - 1.6*x**2 
ax7.plot(x, y)
ax7.set_ylim(ax7.get_ylim()[0]-1.5, ax7.get_ylim()[1])
ax7.set_xlim(ax7.get_xlim()[0]-0.5, ax7.get_xlim()[1]+0.5)
ax7.scatter(1/2*(ax7.get_xlim()[0] + ax7.get_xlim()[1]), 1.2, marker = 'o', s=900, facecolors='none')
width_l = ax7.get_ylim()[1] - ax7.get_ylim()[0]
lines = []
for t in np.linspace(0, 1, 40):
l, = ax7.plot(x, y - t * 0.1 * width_l, color=cmap(t/2 + 0.25))
lines.append(l)


plot_rainbow()
fig.canvas.mpl_connect("resize_event", plot_rainbow)
fig.canvas.mpl_connect("button_release_event", plot_rainbow)

format_axes(fig)

# Save the figure (.pdf)
plt.tight_layout()
plt.savefig('fig.pdf')

obrazek
obrazek761×534 19.9 KB

2

What do you mean by “color transit”?

Could you possibly simplify the example at all?

3

I mean the colour in the upper figure is changing from dark grey to light grey. But on the second figure, there is a wide strip of light grey. I would like the appearance of the second figure similar to the first one.

When I want to edit my code, I got an error: You are not permitted to view the requested resource.
The function def format_axes(fig): is redundant in the code.

4

Here is the code for generating only the last figure which is wrong.

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]

cmap = plt.get_cmap('Greys_r')

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)
ax6 = fig.add_subplot(gs[2, :3])

# 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')