How to Sort CSV Files Using 'csvsort' (with examples)

csvsort is a versatile command-line tool included in the csvkit library, designed to sort CSV files efficiently. It allows users to sort data by one or more columns, specifying the order and the data type inference as needed. This capability is essential for organizing data, preparing it for analysis, or simply making information easier to read and interpret.

Use case 1: Sorting a CSV file by column 9

Code:

csvsort -c 9 data.csv

Motivation:

Suppose you work in data analytics and have a CSV file containing daily transaction records, with each transaction containing numerous attributes spread across columns. Column 9 might represent the transaction value, and you want to sort the entire file based on this information to gain insights into the highest and lowest values or identify patterns.

Explanation:

• csvsort: This is the command being used, which sorts CSV files.
• -c 9: The -c option specifies the column by which to sort. In this case, column 9 is the focus, meaning that the rest of the file will be rearranged based on the values found in this column.
• data.csv: This is the input file that contains the CSV data you wish to sort.

Example Output:

Assume data.csv looks like this before sorting:

ID,Date,Item,Category,Quantity,Price,Location,CustomerID,TransactionValue
1,2023-10-01,Apples,Fruit,10,1.00,StoreA,1234,10.00
2,2023-10-02,Bananas,Fruit,5,0.50,StoreB,5678,2.50
3,2023-10-03,Carrots,Vegetable,8,0.75,StoreA,9101,6.00

After running the command, the data sorted by column 9 would look like:

ID,Date,Item,Category,Quantity,Price,Location,CustomerID,TransactionValue
2,2023-10-02,Bananas,Fruit,5,0.50,StoreB,5678,2.50
3,2023-10-03,Carrots,Vegetable,8,0.75,StoreA,9101,6.00
1,2023-10-01,Apples,Fruit,10,1.00,StoreA,1234,10.00

Use case 2: Sorting a CSV file by the “name” column in descending order

Code:

csvsort -r -c name data.csv

Motivation:

Imagine you’re a recruitment manager organizing a list of applicants stored in a CSV file. This file includes a column labeled “name”, sorted in ascending order, but you now need to sort these names in descending order to review or publish profiles starting with the latter part of the alphabet.

Explanation:

• csvsort: This command sorts the content of CSV files.
• -r: This flag indicates that the sorting order should be reversed, meaning it will be done in descending order.
• -c name: Here, -c specifies the sorting key, which, in this case, is the column labeled “name”.
• data.csv: This represents the input CSV file that contains your data, where each entry has a “name” column.

Example Output:

Before sorting:

ID,name,Position,Department,Salary
1,Anna,Analyst,Finance,60000
2,John,Manager,HR,75000
3,Susan,Director,IT,90000

After sorting in descending order by “name”:

ID,name,Position,Department,Salary
3,Susan,Director,IT,90000
2,John,Manager,HR,75000
1,Anna,Analyst,Finance,60000

Use case 3: Sorting a CSV file by column 2, then by column 4

Code:

csvsort -c 2,4 data.csv

Motivation:

You may be coordinating an academic conference with multiple sessions scattered across various dates. Column 2 holds session dates, and column 4 contains session titles. Sorting your file first by date and then by title can help you quickly verify the session schedule or generate an itinerary for participants.

Explanation:

• csvsort: The tool used to handle sorting operations for CSV files.
• -c 2,4: This option specifies a multiple-column sort. This means that the CSV file will first be sorted by the second column (column 2), and within each grouping of those results, it will be further sorted by the fourth column (column 4).
• data.csv: The input file, which contains the CSV data you need to organize.

Example Output:

Before sorting:

SessionID,Date,Speaker,Title
1,2023-11-02,Dr. Smith,Astronomy Basics
2,2023-11-01,Prof. Brown,Quantum Mechanics
3,2023-11-01,Dr. Taylor,Advanced Calculus

After sorting by Date, then by Title:

SessionID,Date,Speaker,Title
3,2023-11-01,Dr. Taylor,Advanced Calculus
2,2023-11-01,Prof. Brown,Quantum Mechanics
1,2023-11-02,Dr. Smith,Astronomy Basics

Use case 4: Sorting a CSV file without inferring data types

Code:

csvsort --no-inference -c columns data.csv

Motivation:

In some cases, you might be dealing with a dataset where numerical data is encoded in a non-standard format (e.g., ‘001’, ‘010’), and converting these to integers during the sorting process would lead to incorrect results. Using csvsort without inferring data types ensures the sorting respects the original format.

Explanation:

• csvsort: The command-line utility for sorting CSV files.
• --no-inference: This flag disables automatic data type inference, ensuring that all data is treated as text strings. It allows for sorting data exactly as it appears in the CSV file, without altering formats or attempting any type conversion.
• -c columns: The -c option indicates the specific columns you wish to sort, which should be listed in place of columns as needed.
• data.csv: The name of the CSV file you are manipulating.

Example Output:

Before sorting:

ID,BatchNumber,Product,Quantity
1,001,Biscuits,100
2,010,Biscuits,200
3,002,Chocolates,50

After sorting by BatchNumber, without inferring data types:

ID,BatchNumber,Product,Quantity
1,001,Biscuits,100
3,002,Chocolates,50
2,010,Biscuits,200

The BatchNumber remains as entered, preserving the leading zeros.

Conclusion:

The csvsort command is a powerful tool for sorting CSV data in various ways—by multiple columns, in different orders, and without necessarily converting data types. This flexibility makes it especially valuable in data preparation, report generation, and any task requiring organized presentation of tabular data. By mastering csvsort, users can significantly enhance their data management capabilities, ensuring that their information is always accurately and conveniently displayed.