Posts Tagged ‘plotting’

Python: Data Visualization Part-2

January 10, 2021 Leave a comment

Learning : python, pygal, Data Visualization,Line Chart
Subject: Data visualization using pygal library

In this post we will talk about Line-chart using pygal library in python, Line-chart has three sub-type as: Basic, Stacked ,Time. We will use the data-set for Average age of Males and Females at first Marage during 6 yeaars (2000 and 2006), the code line to set the data data will be as :

line_chart.add(‘Males’, [30,20,23,31,39,44])

Line-chart: Basic
This is very normal and basic chart we use in all reports, we are feeding the data for Males and Females average age in first marage.. here is the code and the output ..


import pygal 

line_chart = pygal.Line()

line_chart.add('Males', [30,20,23,31,39,44]) 


line_chart.title = "Males and Females first Marage Age (average)"


Line-chart: Stacked Line Stacked chart (fill) will put all the data in top of each other. Here is the code.

Line-chart: Time Line Last type just to add or format the x_lables of the chart, we can use lambda function to do this (we can use lambda function with any other chart types), here we will do two example, one is using full time/date and another just write the month-year as string and will use the lambda function to calculate second data-set of Tax’s based on the salary amount..

import pygal 
from datetime import datetime, timedelta
d_chart = pygal.Line()

d_chart.add('Males', [30,20,23,31,39,44]) 

d_chart.x_labels = map(lambda d: d.strftime('%Y-%m-%d'), [
 datetime(2000, 1, 2),
 datetime(2001, 1, 12),
 datetime(2002, 3, 2),
 datetime(2003, 7, 25),
 datetime(2004, 1, 11),
 datetime(2005, 9, 5)])

d_chart.title = "Males and Females first Marage Age (average)"


To give better example of using lambda function, we will say: we have a salaries for 6 years (May-2000 to May-2006) and a Tax of 0.25, we will let the lambda function to calculate the Tax amount for each salary. Here is the code ..

 # Using lambda to calculate Tax amount

import pygal 
d_chart = pygal.Line()

d_chart.add('Salary', [550,980,1200,1800,2200,3500]) 

d_chart.add('Tax',map(lambda t: t*0.25, [550,980,1200,1800,2200,3500]))
d_chart.x_labels = map(str,(

d_chart.title = "Salary and Tax (0.25) payment in 6 years"


Next we will talk about Histogram chart.

:: Data Visualization using pygal ::

Line Chart
Part-3 Part-4

Follow me on Twitter..

By: Ali Radwani

Python: Data Visualization Part-1

January 6, 2021 1 comment

Learning : python, pygal, Data Visualization, Bar Chart
Subject: Data visualization using pygal library

pygal is a Data Visualization library in python to help us showing our Data as a graph. In coming several posts we will discover and learn how to use the pygal library in simple and easy configuration and style.

First we need to install pygal packeg, to do so write this:
pip install pygal

Now we need some Data to show, in this leson I am using aGalaxy Tab S4, so all the codes will be tested and applyed on website [ alow us to use pygal package online so we don’t need to install it on our divice]

Type of Chart:
pygal has several types of charts that we can use, here we will list them all then in coming posts will use each one with simple data. So what we have:
Line, Bar, Histogram, XY,
Pie, Radar, Box, Dot,
Funnel, SolidGauge, Gauge, Pyramid,
Treemap, Maps

Some of those charts has a sub-types such as in Bar char we have: Basic, Stacked and Horizontal. Also for each chart we can add a title and labels and we can use some styles.

So let’s start ..
First we will go for the Bar chart, and we have three sub-types as Basic, Stacked and Horizontal.

First chart: Bar chart:
In this part we will demonstrate the Bar Chart, it has three sub-types as Basic, Stacked and Horizontal.

We assume that our data is the Males and Female ages on first marage, the data will be as dictionary (later we will see how to customize each bar)

 # Basic Bar Chart using pygal

import pygal 
bar_chart = pygal.Bar() # To create a bar graph object
bar_chart.add('Females', [22,25,18,35,33,18]) 
bar_chart.add('Males', [30,20,23,31,39,44]) 

bar_chart.title = "Males and Females First Marage Age"

Sample code for Basic bar chart

Another sub-type in Bar chart is Horizontal-Bar, it is semelar to the Basic but as if fliped 90 degree. Here is the code ..

 # Horizontal Bar Chart using pygal

import pygal

# HorizontalBar()
HBar = pygal.HorizontalBar()
HBar.add('Females', [22,25,18,35,33,18]) 
HBar.add('Males', [30,20,23,31,39,44]) 

HBar.title = "Males and Females First Marage Age"



Sample code for Horizontal Bar chart

Last sub-type in Bar chart is Stacked Bar were all data of each element will be in one bar. Here is the code and example..

 # Stacked Bar Chart using pygal

import pygal 
# StackedBar() 
stackedbar = pygal.StackedBar()
stackedbar.add('Females', [22,25,18,35,33,18]) 
stackedbar.add('Males', [30,20,23,31,39,44]) 
stackedbar.title = "Males and Females First Marage Age"


If we say we have another data-set as “age in First-Divorces” and we want to add this set to the Stacked Bar chart, then we first will create the data-set as:
stackedbar.add(‘Divorses’, [35,22,45,33,40,38])
and we will arrange the code line to be at top,middle or bottom of the bar. Here is the code..

Sample code for stacke Bar chart with Divorce data

Next we will talk about Line chart.

:: Data Visualization using pygal ::

Part-2 Part-3 Part-4

Follow me on Twitter..

By: Ali Radwani

Python ploting

November 21, 2019 Leave a comment

Learning : Plotting Data using python and numpy
Subject: Plotting Data

The best way to show the data is to make them as a graph or charts, there are several charts type and names each will present your data in a different way and used for different purpose. Plotting the data using python is a good way to show out your data and in coming posts we will cover very basic aspects in plotting data. So if we just want to show a sample for what we are talking about, we will say: we have a sample of hospital data for born childs (male m, female f, in years 200 to 2003).

:: Click to enlarge ::

There are some libraries we can use in python to help us plotting the data, here are some of them. Matplotlib, Plotly and Seaborn are just samples of what we may use, in this post we will use the Matplotlib. To use Matplotlib we need to install it, so if it is not installed in your python you need to do so.

pip install Matplotlib

Then we need to import it in our code using :

import matplotlib.pyplot as plt

To show the data we need to have some variables that will be used in our first example, So the case is that we have some data from a hospital, the data are numbers of born childs (male m, female f) in years 2000 to 2003. We will store/save the data in list, we will have data_yesrs =[2000,2001,2002,2003], then we will have male born data in data_m=[2,2.5,3,5] and female born data data_f = [3,3.8,4,4.5], the chart will have two axis vertical is Y y_data_title =’In Hundreds’ and horizontal is X x_data_title =’ Years’, now to project all this information on a chart we use this code ..

import matplotlib.pyplot as plt
data_yesrs = [2000,2001,2002,2003] # years on X axis 
data_m = [2,2.5,3,5]   # y data males born
data_f = [3,3.8,4,4.5]  # y data female born
y_data_title ='In Thousands'
x_data_title =' Years'

plt.title('New Born babies')

plt.plot(data_yesrs,data_m,'r-', data_yesrs,data_f,'b--')

Another way to plot the data were we can use a one line for each data set as:

We can see that male data is red line, and female data is blue dashes, we can use some line style to present the data as mentioned bellow:

‘-‘ or ‘solid’ is solid line
‘–‘ or ‘dashed’ is dashed line
‘-.’ or ‘dashdot’ is dash-dotted line
‘:’ or ‘dotted’ is dotted line
‘None’ or ‘ ‘ or ” is draw nothing

And also we can use colors such as :
r: red, g: green,
b: blue, y: yellow .

If we want to add the map or chart key, we need first to import matplotlib.patches as mpatches then to add this line of code:

and the keys [‘Male’,’Female’] MUST be in the same sequence as the main plot code line :
plt.plot(data_yesrs,data_m,’r-‘, data_yesrs,data_f,’b–‘)

To Download my Python code (.py) files Click-Here

Follow me on Twitter..