How to use the command 'csvgrep' (with examples)

The ‘csvgrep’ command is a tool included in the csvkit package that allows users to filter rows in a CSV file based on string and pattern matching. It provides a flexible way to search for specific data in CSV files, making it a handy tool for data analysis and data manipulation tasks.

Use case 1: Find rows that have a certain string in column 1

Code:

csvgrep -c 1 -m string_to_match data.csv

Motivation:

The motivation for using this example is to filter the rows in a CSV file and only keep the ones that have a specific string in a particular column. This can be useful when working with large datasets and you only need to focus on the rows that meet certain criteria.

Explanation:

• csvgrep is the command to execute the ‘csvgrep’ tool.
• -c 1 specifies that we want to search for the specified string in column 1 of the CSV file.
• -m string_to_match specifies the string that we want to match in the specified column.
• data.csv is the input CSV file that we want to filter.

Example Output:

Assuming the input CSV file (data.csv) contains the following rows:

name,age,city
John Doe,25,New York
Jane Smith,32,San Francisco
Mike Johnson,29,Chicago

Running the command csvgrep -c 1 -m "John Doe" data.csv will produce the following output:

name,age,city
John Doe,25,New York

This means that only the row with the name “John Doe” in column 1 is returned, and the other rows are filtered out.

Use case 2: Find rows in which columns 3 or 4 match a certain regular expression

Code:

csvgrep -c 3,4 -r regular_expression data.csv

Motivation:

The motivation for using this example is to filter rows based on a regular expression pattern in multiple columns. This can be useful when you want to find rows that match certain complex patterns or when you need to search for specific data that is distributed across different columns in the CSV file.

Explanation:

• csvgrep is the command to execute the ‘csvgrep’ tool.
• -c 3,4 specifies that we want to search for the specified regular expression in columns 3 and 4 of the CSV file.
• -r regular_expression specifies the regular expression pattern that we want to match in the specified columns.
• data.csv is the input CSV file that we want to filter.

Example Output:

Assuming the input CSV file (data.csv) contains the following rows:

name,age,email,phone
John Doe,25,johndoe@example.com,1234567890
Jane Smith,32,janesmith@example.com,0987654321
Mike Johnson,29,mikejohnson@example.com,9876543210

Running the command csvgrep -c 3,4 -r "@example.com" data.csv will produce the following output:

name,age,email,phone
John Doe,25,johndoe@example.com,1234567890
Jane Smith,32,janesmith@example.com,0987654321
Mike Johnson,29,mikejohnson@example.com,9876543210

This means that all rows with email addresses matching the regular expression pattern “@example.com” in columns 3 and 4 are returned.

Use case 3: Find rows in which the “name” column does NOT include the string “John Doe”

Code:

csvgrep -i -c name -m "John Doe" data.csv

Motivation:

The motivation for using this example is to filter out rows that contain a specific string in a specific column. This can be useful when you want to exclude certain rows from your analysis or when you need to clean up your data by removing unwanted entries.

Explanation:

• csvgrep is the command to execute the ‘csvgrep’ tool.
• -i specifies that the matching should be case-insensitive.
• -c name specifies that we want to search for the specified string in the “name” column of the CSV file.
• -m "John Doe" specifies the string that we want to exclude from the “name” column.
• data.csv is the input CSV file that we want to filter.

Example Output:

Assuming the input CSV file (data.csv) contains the following rows:

name,age,city
John Doe,25,New York
Jane Smith,32,San Francisco
Mike Johnson,29,Chicago

Running the command csvgrep -i -c name -m "John Doe" data.csv will produce the following output:

name,age,city
Jane Smith,32,San Francisco
Mike Johnson,29,Chicago

This means that all rows with names that do not include the string “John Doe” in the “name” column are returned, while the row with the name “John Doe” is excluded from the output.

Conclusion:

The ‘csvgrep’ command is a useful tool for filtering rows in CSV files based on specific criteria. It allows users to search for strings and patterns in one or more columns, providing a flexible way to extract relevant data from large datasets. By understanding how to use the different options of the ‘csvgrep’ command, users can effectively manipulate and analyze their CSV files with ease.