read_csv in pandas in Python – how does it work?

read_csv in pandas in Python

Overview

The pandas.read_csv() function is a powerful utility in the Pandas library that allows you to read data from a CSV (Comma-Separated Values) file into a Pandas DataFrame. This function is widely used in data analysis to load datasets for processing and manipulation. It simplifies the process of converting raw CSV data into a structured format that can be easily analyzed and manipulated using Pandas’ various tools and functions.

Syntax

The basic syntax of the pandas.read_csv() function is as follows:

pandas.read_csv(filepath_or_buffer, sep=',', delimiter=None, header='infer', names=None, 
                 skiprows=None, skipfooter=0, na_values=None, 
                 parse_dates=False, dtype=None, 
                 engine='c', encoding='utf-8', 
                 compression='infer', 
                 thousands=None, 
                 decimal='.', 
                 lineterminator=None, 
                 quotechar='"', 
                 quoting=0, 
                 doublequote=True, 
                 escapechar=None, 
                 comment=None, 
                 parse_dates=False, 
                 error_bad_lines=None, 
                 warn_bad_lines=None, 
                 skip_blank_lines=True, 
                 chunksize=None, 
                 skipinitialspace=False, 
                 na_filter=True, 
                 keep_default_na=True, 
                 convert_float=True, 
                 verbose=False, 
                 memory_map=False, 
                 low_memory=True, 
                 float_precision=None)

Parameters

  • filepath_or_buffer: The name of the CSV file or a file-like object.
  • sep: The delimiter that separates the values (default is a comma).
  • header: Row number(s) to use as the column names; defaults to ‘infer’.
  • names: List of column names to use if there is no header row.
  • skiprows: Number of rows to skip at the start of the file.
  • na_values: Additional strings to recognize as NA/NaN.
  • parse_dates: Parsing dates to datetime format.
  • encoding: Encoding to use for reading the file (e.g., ‘utf-8’).

Example

Let’s consider a scenario where we have a CSV file named employee_sales.csv containing sales data. The file has the following structure:

Employee,Product,Month,Sales
Alice,Widget A,2023-01,200
Bob,Widget B,2023-01,150
Alice,Widget B,2023-02,300
Bob,Widget A,2023-02,200

We want to load this data into a Pandas DataFrame and analyze the sales performance of each employee.

We can use the pandas.read_csv() function like this:

import pandas as pd

# Load the CSV file into a DataFrame
df = pd.read_csv('employee_sales.csv')

# Display the DataFrame
print(df)

The resulting DataFrame will look like this:

  Employee  Product      Month  Sales
0    Alice  Widget A  2023-01    200
1      Bob  Widget B  2023-01    150
2    Alice  Widget B  2023-02    300
3      Bob  Widget A  2023-02    200

Now we have the sales data structured in a DataFrame format, which allows us to perform further analysis, such as grouping sales by employee or product, calculating total sales, or visualizing the data.