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https://github.com/simonw/csv-diff

Python CLI tool and library for diffing CSV and JSON files
https://github.com/simonw/csv-diff

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Python CLI tool and library for diffing CSV and JSON files

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README 

        
# csv-diff



[![PyPI](https://img.shields.io/pypi/v/csv-diff.svg)](https://pypi.org/project/csv-diff/)

[![Changelog](https://img.shields.io/github/v/release/simonw/csv-diff?include_prereleases&label=changelog)](https://github.com/simonw/csv-diff/releases)

[![Tests](https://github.com/simonw/csv-diff/workflows/Test/badge.svg)](https://github.com/simonw/csv-diff/actions?query=workflow%3ATest)

[![License](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](https://github.com/simonw/csv-diff/blob/main/LICENSE)



Tool for viewing the difference between two CSV, TSV or JSON files. See [Generating a commit log for San Francisco’s official list of trees](https://simonwillison.net/2019/Mar/13/tree-history/) (and the [sf-tree-history repo commit log](https://github.com/simonw/sf-tree-history/commits)) for background information on this project.



## Installation



    pip install csv-diff



## Usage



Consider two CSV files:



`one.csv`



    id,name,age

    1,Cleo,4

    2,Pancakes,2



`two.csv`



    id,name,age

    1,Cleo,5

    3,Bailey,1



`csv-diff` can show a human-readable summary of differences between the files:



    $ csv-diff one.csv two.csv --key=id

    1 row changed, 1 row added, 1 row removed



    1 row changed



      Row 1

        age: "4" => "5"



    1 row added



      id: 3

      name: Bailey

      age: 1



    1 row removed



      id: 2

      name: Pancakes

      age: 2



The `--key=id` option means that the `id` column should be treated as the unique key, to identify which records have changed.



The tool will automatically detect if your files are comma- or tab-separated. You can over-ride this automatic detection and force the tool to use a specific format using `--format=tsv` or `--format=csv`.



You can also feed it JSON files, provided they are a JSON array of objects where each object has the same keys. Use `--format=json` if your input files are JSON.



Use `--show-unchanged` to include full details of the unchanged values for rows with at least one change in the diff output:



    % csv-diff one.csv two.csv --key=id --show-unchanged

    1 row changed



      id: 1

        age: "4" => "5"



        Unchanged:

          name: "Cleo"



### JSON output



You can use the `--json` option to get a machine-readable difference:



    $ csv-diff one.csv two.csv --key=id --json

    {

        "added": [

            {

                "id": "3",

                "name": "Bailey",

                "age": "1"

            }

        ],

        "removed": [

            {

                "id": "2",

                "name": "Pancakes",

                "age": "2"

            }

        ],

        "changed": [

            {

                "key": "1",

                "changes": {

                    "age": [

                        "4",

                        "5"

                    ]

                }

            }

        ],

        "columns_added": [],

        "columns_removed": []

    }



### Adding templated extras



You can specify additional keys to be displayed in the human-readable format using the `--extra` option:



    --extra name "Python format string with {id} for variables"



For example, to output a link to `https://news.ycombinator.com/latest?id={id}` for each item with an ID, you could use this:



```bash

csv-diff one.csv two.csv --key=id \

  --extra latest "https://news.ycombinator.com/latest?id={id}"

```

These extras display something like this:

```

1 row changed



  id: 41459472

    points: "24" => "25"

    numComments: "5" => "6"

  extras:

    latest: https://news.ycombinator.com/latest?id=41459472

```



## As a Python library



You can also import the Python library into your own code like so:



    from csv_diff import load_csv, compare

    diff = compare(

        load_csv(open("one.csv"), key="id"),

        load_csv(open("two.csv"), key="id")

    )



`diff` will now contain the same data structure as the output in the `--json` example above.



If the columns in the CSV have changed, those added or removed columns will be ignored when calculating changes made to specific rows.



## As a Docker container



### Build the image



    $ docker build -t csvdiff .



### Run the container



    $ docker run --rm -v $(pwd):/files csvdiff



Suppose current directory contains two csv files : one.csv two.csv



    $ docker run --rm -v $(pwd):/files csvdiff one.csv two.csv

    

## Alternatives



- [csvdiff](https://github.com/aswinkarthik/csvdiff) is a "fast diff tool for comparing CSV files" - you may get better results from this than from `csv-diff` against larger files.