Python Matplotlib Pie Chart Primer Tutorial
We’re off on a new discovery tour regarding …
- Python … as a programming language, and it’s module …
- Matplotlib
- command line Pie Chart application … Python pie_chart_python.py (superceeding this) …
# pie_chart_python.py
# September - 2026
# RJM Programming
# Thanks to https://www.w3schools.com/python/default.asp
import os
import matplotlib
# Set backend to Agg before importing pyplot
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
#import plotly.express as px
from PIL import Image
nums = []
sofar = 0
if len(nums) <= 0:
while sofar < 100:
print(f"Enter your percentage value regarding a pie chart where so far {sofar} has already been allocated.")
anum = input()
nums.append(int(anum))
sofar += int(anum)
y = np.array(nums)
fig, ax = plt.subplots()
ax.pie(y)
fig.savefig("plot.png")
# 1. Load the image
img = mpimg.imread('plot.png')
# 2. Process or manipulate the image (Optional)
# For example, let's look at the shape or apply changes
#print(f"Image shape: {img.shape}")
# 3. Create the plot without displaying it
plt.imshow(img)
plt.axis('off') # Hide axis lines and labels
# 4. Save the result to a file instead of showing it
plt.savefig('output_image.png', bbox_inches='tight', pad_inches=0)
plt.close()
# Open the PNG image file
#with Image.open("plot.png") as img:
# Display the image using your system's default viewer
#img.show()
# Optional: Load the data into memory so you can safely close the file
#img.load()
exit()
… and … - working on our local Apache/PHP MAMP web server (only, so far, the reason being our public web server has no graphical $DISPLAY existant, and so the plt.show() Python codeline cannot be used, so we need to think more on integrations there) … PHP pie_chart_python.php …
<?php
// pie_chart_python.php
// RJM Programming - September, 2026
if (php_sapi_name() === 'cli') {
$command = '/usr/local/bin/python3 ' . dirname(__FILE__) . DIRECTORY_SEPARATOR . 'piechartpython.py'; // Your command
if (1 == 1) {
exec($command);
} else {
// Open the process pointer for reading
$handle = popen($command, 'r');
if ($handle) {
// Read and output the buffer until the end of the file
while (!feof($handle)) {
echo fread($handle, 2048);
flush(); // Send it to the browser immediately
}
pclose($handle);
}
}
exit;
} else if (strpos(str_replace('?','',$_SERVER['QUERY_STRING']), '&') === false) {
$waspy=file_get_contents(dirname(__FILE__) . DIRECTORY_SEPARATOR . 'pie_chart_python.py');
if (strpos($waspy, "nums = []") !== false) {
if (isset($_GET['array'])) {
file_put_contents(dirname(__FILE__) . DIRECTORY_SEPARATOR . 'piechartpython.py', str_replace("nums = []","nums = [" . str_replace('+',' ',urldecode($_GET['array'])) . "]",$waspy));
}
}
//exec('php ' . dirname(__FILE__) . DIRECTORY_SEPARATOR . 'pie_chart_python.php > /dev/null 2> /dev/null');
exec('cd ' . dirname(__FILE__) . DIRECTORY_SEPARATOR . ' ; /Applications/MAMP/bin/php/php7.4.33/bin/php -n ./pie_chart_python.php > /dev/null 2> /dev/null ; open ./plot.png');
sleep(3);
}
echo "<html><body style=\"background:url(./plot.png);background-repeat:no-repeat;background-size:contain;\"></body></html>";
?>
… starting down this road with a simple …
… allowing a web browser address bar URL such as …
http://localhost:8888/pie_chart_python.php?array=12,5,1,68
… working for us, here, locally, displaying a Pie Chart …
… via our local Python3 Matplotlib modularized environment.
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