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Pandas

This topic matters as it relates to learning about Pandas and how to implement them to analyze data in Python.

What is pandas

Pandas is a python library with a set of tools to do data analysis. If it involves data we need to know how to use pandas. It uses fast, flexible, and expressive data structures designed to make working with relational or labeled data both easy and intuitive. It allows us to:

  • Load data
  • Prepare data
  • Manipulate data
  • Model data
  • Analyze data

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Working with pandas

First we need import the pandas package to be able to load it.

In [1]: import pandas as pd

Using pd is the standard practice for all pandas documentation.

Data Frame & Series

A DataFrame is a 2-dimensional data structure that can store data of different types (including characters, integers, floating point values, categorical data and more) in columns. It is similar to a spreadsheet, a SQL table or the data.frame in R. Represented as a table. Each column in a DataFrame is a Series. We can do things by applying a method to a DataFrame or Series.

Reading and Exporting Data

The read_csv() function allows us to read data stored as a csv file into a pandas DataFrame. Pandas support many different file formats or data sources out of the box (csv, excel, sql, json, parquet, etc.), each of them with the prefix read_*. To export data out of pandas we use the different to_* methods.

There are other methods like head, tail, info and dtypes attribute, that are very convenient for a first check.

Selecting from a Data Frame

  • We use square brackets []. Inside the brackets, we can use a single column / row label, a list of column / row labels, a slice of labels, a conditional expression or a colon.
  • We can select specific rows and / or columns using loc when using the row and column names, and iloc when using the positions in the table.
  • We can assign new values to a selection based on loc / iloc.

Creating plots in pandas

We need to import it:

In [1]: import pandas as pd
In [2]: import matplotlib.pyplot as plt

The .plot.* methods are applicable on both Series and DataFrames. By default, each of the columns is plotted as a different element (line, boxplot, etc.). Any plot created by pandas is a Matplotlib object.

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Things I want to know more about

  • I would like to know more about how to implement pandas efficiently to analyze data in Python.

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