Adding color to radar chart in python

[swisha]

Hello,

What code do I use to change the color background of a radar chart using python.
I want to use a sequential color scheme from light blue to dark blue.
I assume that the starting point would be from matplotlib.pypl ot using the cmaps.

Any help is appreciated.

[SioSio]

col indicates an RGB color between 0.0 and 1.0.
It can change the background color by adjusting RGB.

    fig = plt.figure()
:
:
:
    col = [0.0, 0.0, 1.0]
    fig.savefig(imgname, facecolor=col)

[swisha]

Thanks for the help.

How do I code the 'Blues' from the sequential colormap as found on this page: https://matplotlib.org/tutorials/colors/colormaps.html

[SioSio]

Hexadecimal or RGB specified, change the blue color as shown below.
'#0000ff' is the same as [0.0, 0.0, 1.0].

fig = plt.figure()
col1 = [0.3, 0.2, 0.5]
col2 = [0.2, 0.3, 0.5]
col3 = [0.1, 0.3, 0.5]
col4 = [0.0, 0.3, 0.6]
col5 = [0.0, 0.3, 0.7]
col6 = [0.0, 0.2, 0.8]
col7 = [0.0, 0.1, 0.9]
colorlist = [col1, col2, col3, col4, col5, col6, col7, '#0000ff']
x = np.arange(1, 9)
height = np.arange(1, 9)
plt.barh(x, height, color=colorlist, tick_label=colorlist, align="center")
fig.savefig("test1.png")

[swisha]

Where would I code that into this example. I want to change the background of the radar chart with the "Blues' Sequential colormap.

# Plots a radar chart.
 
from math import pi
import matplotlib.pyplot as plt
 
 
# Set data
cat = ['Speed', 'Reliability', 'Comfort', 'Safety', 'Effieciency']
values = [90, 60, 65, 70, 40]
 
N = len(cat)
 
x_as = [n / float(N) * 2 * pi for n in range(N)]
 
# Because our chart will be circular we need to append a copy of the first 
# value of each list at the end of each list with data
values += values[:1]
x_as += x_as[:1]
 
 
# Set color of axes
plt.rc('axes', linewidth=0.5, edgecolor="#888888")
 
 
# Create polar plot
ax = plt.subplot(111, polar=True)
 
 
# Set clockwise rotation. That is:
ax.set_theta_offset(pi / 2)
ax.set_theta_direction(-1)
 
 
# Set position of y-labels
ax.set_rlabel_position(0)
 
 
# Set color and linestyle of grid
ax.xaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)
ax.yaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)
 
 
# Set number of radial axes and remove labels
plt.xticks(x_as[:-1], [])
 
# Set yticks
plt.yticks([20, 40, 60, 80, 100], ["20", "40", "60", "80", "100"])
 
 
# Plot data
ax.plot(x_as, values, linewidth=2, linestyle='solid', zorder=3)
 
# Fill area
ax.fill(x_as, values, 'b', alpha=0.0)
 
 
# Set axes limits
plt.ylim(0, 100)
 
 
# Draw ytick labels to make sure they fit properly
for i in range(N):
    angle_rad = i / float(N) * 2 * pi
 
    if angle_rad == 0:
        ha, distance_ax = "center", 10
    elif 0 < angle_rad < pi:
        ha, distance_ax = "left", 1
    elif angle_rad == pi:
        ha, distance_ax = "center", 1
    else:
        ha, distance_ax = "right", 1
 
    ax.text(angle_rad, 100 + distance_ax, cat[i], size=10, horizontalalignment=ha, verticalalignment="center")
 
 
# Show polar plot
plt.show()

Thanks for the help. I am a total beginner with python.

[SioSio]

Ex.
Write at the beginning of the code.

import matplotlib.pyplot as plt
import numpy as np
from math import pi

col1 = [0.0,0.0,1.0]
fig = plt.figure()
fig.patch.set_facecolor(col1)

[swisha]

Thanks for the reply but not quite what I was after but helpful.

How do I change color of the actual chart with a sequential background, starting from blue in the middle of the circle to light blue on the outer edges?

[SioSio]

Use matplotlib.pypl ot.fill_between .
However, I do not know how to fill in a circle.

ax.fill_between(x_as, 0, 20, color=col1)
ax.fill_between(x_as, 20, 40, color=col2)
ax.fill_between(x_as, 40, 60, color=col3)
ax.fill_between(x_as, 60, 80, color=col4)
ax.fill_between(x_as, 80, 100, color=col5)

[lewish95]

# Libraries
import matplotlib.pyplot as plt
import pandas as pd
from math import pi
 
# Set data
df = pd.DataFrame({
'group': ['A','B','C','D'],
'var1': [38, 1.5, 30, 4],
'var2': [29, 10, 9, 34],
'var3': [8, 39, 23, 24],
'var4': [7, 31, 33, 14],
'var5': [28, 15, 32, 14]
})
 
# ------- PART 1: Define a function that do a plot for one line of the dataset!
 
def make_spider( row, title, color):
 
# number of variable
categories=list(df)[1:]
N = len(categories)
 
# What will be the angle of each axis in the plot? (we divide the plot / number of variable)
angles = [n / float(N) * 2 * pi for n in range(N)]
angles += angles[:1]
 
# Initialise the spider plot
ax = plt.subplot(2,2,row+1, polar=True, )
 
# If you want the first axis to be on top:
ax.set_theta_offset(pi / 2)
ax.set_theta_direction(-1)
 
# Draw one axe per variable + add labels labels yet
plt.xticks(angles[:-1], categories, color='grey', size=8)
 
# Draw ylabels
ax.set_rlabel_position(0)
plt.yticks([10,20,30], ["10","20","30"], color="grey", size=7)
plt.ylim(0,40)
 
# Ind1
values=df.loc[row].drop('group').values.flatten().tolist()
values += values[:1]
ax.plot(angles, values, color=color, linewidth=2, linestyle='solid')
ax.fill(angles, values, color=color, alpha=0.4)
 
# Add a title
plt.title(title, size=11, color=color, y=1.1)
 
# ------- PART 2: Apply to all individuals
# initialize the figure
my_dpi=96
plt.figure(figsize=(1000/my_dpi, 1000/my_dpi), dpi=my_dpi)
 
# Create a color palette:
my_palette = plt.cm.get_cmap("Set2", len(df.index))
 
# Loop to plot
for row in range(0, len(df.index)):
make_spider( row=row, title='group '+df['group'][row], color=my_palette(row))

I hope this code helps!