Data Visualization Using Python

In this example we’ll perform different Data Visualization charts on Population Data. There’s an easy way to create visuals directly from Pandas, and we’ll see how it works in detail in this tutorial.

Install neccessary Libraries

To easily create interactive visualizations, we need to install Cufflinks. This is a library that connects Pandas with Plotly, so we can create visualizations directly from Pandas (in the past you had to learn workarounds to make them work together, but now it’s simpler) First, make sure you install Pandas and Plotly running the following commands on the terminal:

Install the following labraries in the this order – on Conda CMD prompt pip install pandas pip install plotly pip install cufflinks

Import the following Libraries

import pandas as pd
import cufflinks as cf
from IPython.display import display,HTML
cf.set_config_file(sharing='public',theme='ggplot',offline=True)

In this case, I’m using the ‘ggplot’ theme, but feel free to choose any theme you want. Run the command cf.getThemes() to get all the themes available. To make interactive visualizations with Pandas in the following sections, we only need to use the syntaxdataframe.iplot().

The data We’ll use a population dataframe. First, download the CSV file from Kaggle.com, move the file where your Python script is located, and then read it in a Pandas dataframe as shown below.

#Format year column to number with no decimals
df_population = pd.read_csv('documents/population/population.csv')
#use a list of indexes:
print(df_population.loc[[0,10]])
   country    year    population
0    China  2020.0  1.439324e+09
10   China  1990.0  1.176884e+09
print(df_population.head(10))
  country    year    population
0   China  2020.0  1.439324e+09
1   China  2019.0  1.433784e+09
2   China  2018.0  1.427648e+09
3   China  2017.0  1.421022e+09
4   China  2016.0  1.414049e+09
5   China  2015.0  1.406848e+09
6   China  2010.0  1.368811e+09
7   China  2005.0  1.330776e+09
8   China  2000.0  1.290551e+09
9   China  1995.0  1.240921e+09

This dataframe is almost ready for plotting, we just have to drop null values, reshape it and then select a couple of countries to test our interactive plots. The code shown below does all of this.

# dropping null values
df_population = df_population.dropna()
# reshaping the dataframe
df_population = df_population.pivot(index="year", columns="country", values="population")
# selecting 5 countries
df_population = df_population[['United States', 'India', 'China', 'Nigeria', 'Spain']]
print(df_population.head(10))
country  United States         India         China      Nigeria       Spain
year                                                                       
1955.0     171685336.0  4.098806e+08  6.122416e+08   41086100.0  29048395.0
1960.0     186720571.0  4.505477e+08  6.604081e+08   45138458.0  30402411.0
1965.0     199733676.0  4.991233e+08  7.242190e+08   50127921.0  32146263.0
1970.0     209513341.0  5.551898e+08  8.276014e+08   55982144.0  33883749.0
1975.0     219081251.0  6.231029e+08  9.262409e+08   63374298.0  35879209.0
1980.0     229476354.0  6.989528e+08  1.000089e+09   73423633.0  37698196.0
1985.0     240499825.0  7.843600e+08  1.075589e+09   83562785.0  38733876.0
1990.0     252120309.0  8.732778e+08  1.176884e+09   95212450.0  39202525.0
1995.0     265163745.0  9.639226e+08  1.240921e+09  107948335.0  39787419.0
2000.0     281710909.0  1.056576e+09  1.290551e+09  122283850.0  40824754.0

Lineplot

Let’s make a lineplot to compare how much the population has grown from 1955 to 2020 for the 5 countries selected. As mentioned before, we will use the syntax df_population.iplot(kind=’name_of_plot’) to make plots as shown below.

df_population.iplot(kind='line',xTitle='Years', yTitle='Population',
                    title='Population (1955-2020)')

Barplot

We can make a single barplot on barplots grouped by categories. Let’s have a look.

Single Barplot

Let’s create a barplot that shows the population of each country by the year 2020. To do so, first, we select the year 2020 from the index and then transpose rows with columns to get the year in the column. We’ll name this new dataframe df_population_2020 (we’ll use this dataframe again when plotting piecharts)

df_population_2020 = df_population[df_population.index.isin([2020])]
df_population_2020 = df_population_2020.T

Now we can plot this new dataframe with .iplot(). In this case, I’m going to set the bar color to blue using the color argument.

df_population_2020.iplot(kind='bar', color='blue',
                         xTitle='Years', yTitle='Population',
                         title='Population in 2020')

Barplot grouped by “n” variables

Now let’s see the evolution of the population at the beginning of each decade.

# filter years out
df_population_sample = df_population[df_population.index.isin([1980, 1990, 2000, 2010, 2020])]
# plotting
df_population_sample.iplot(kind='bar', xTitle='Years',
                           yTitle='Population')

Naturally, all of them increased their population throughout the years, but some did it at a faster rate.

Boxplot

Boxplots are useful when we want to see the distribution of the data. The boxplot will reveal the minimum value, first quartile (Q1), median, third quartile (Q3), and maximum value. The easiest way to see those values is by creating an interactive visualization. Let’s see the population distribution of the China.

df_population['China'].iplot(kind='box', color='green', 
                                     yTitle='Population')

Let’s say now we want to get the same distribution but for all the selected countries.

df_population.iplot(kind='box', xTitle='Countries',
                    yTitle='Population')

As we can see, we can also filter out any country by clicking on the legends on the right.

Histogram

A histogram represents the distribution of numerical data. Let’s see the population distribution of the USA and Nigeria.

df_population[['United States', 'Nigeria']].iplot(kind='hist',
                                                xTitle='Population')

Piechart

Let’s compare the population by the year 2020 again but now with a piechart. To do so, we’ll use the df_population_2020 dataframe created in the “Single Barplot” section. However, to make a piechart we need the “country” as a column and not as an index, so we use .reset_index() to get the column back. Then we transform the 2020 into a string.

# transforming data
df_population_2020 = df_population_2020.reset_index()
df_population_2020 =df_population_2020.rename(columns={2020:'2020'})
# plotting
df_population_2020.iplot(kind='pie', labels='country',
                         values='2020',
                         title='Population in 2020 (%)')

Scatterplot

Although population data is not suitable for a scatterplot (the data follows a common pattern), I would make this plot for the purposes of this guide. Making a scatterplot is similar to a line plot, but we have to add the mode argument.

df_population.iplot(kind='scatter', mode='markers')

Whaola! Now you’re ready to make your own beautiful interactive visualization with Pandas.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s