enum.md

enum

Add a new column enumerating rows by adding a column of incremental or uuid identifiers. Can also be used to copy a column or fill a new column with a constant value.

Table of Contents | Source: src/cmd/enumerate.rs | 👆

Description | Examples | Usage | Enum Options | Common Options

Description ↩

Add a new column enumerating the lines of a CSV file. This can be useful to keep track of a specific line order, give a unique identifier to each line or even make a copy of the contents of a column.

The enum function has four modes of operation:

1. INCREMENT. Add an incremental identifier to each of the lines:

$ qsv enum file.csv

2. UUID4. Add a uuid v4 to each of the lines:

$ qsv enum --uuid4 file.csv

3. UUID7. Add a uuid v7 to each of the lines:

$ qsv enum --uuid7 file.csv

3. CONSTANT. Create a new column filled with a given value:

$ qsv enum --constant 0

4. COPY. Copy the contents of a column to a new one:

$ qsv enum --copy names

5. HASH. Create a new column with the deterministic hash of the given column/s. The hash uses the xxHash algorithm and is platform-agnostic. (see https://github.com/DoumanAsh/xxhash-rust for more information):

$ qsv enum --hash 1- // hash all columns, auto-ignores existing "hash" column

$ qsv enum --hash col2,col3,col4 // hash specific columns

$ qsv enum --hash col2 // hash a single column

$ qsv enum --hash /record_id|name|address/ // hash columns that match a regex

$ qsv enum --hash !/record_id/ // hash all columns except the record_id column

Finally, you should also be able to shuffle the lines of a CSV file by sorting on the generated uuid4s:

$ qsv enum --uuid4 file.csv | qsv sort -s uuid4 > shuffled.csv

This will shuffle the lines of the file.csv file as uuids generated using the v4 specification are random and for practical purposes, are unique (1 in 2^122). See https://en.wikipedia.org/wiki/Universally_unique_identifier#Collisions

However, sorting on uuid7 identifiers will not work as they are time-based and monotonically increasing, and will not shuffle the lines.

Examples ↩

Add an incremental index column starting from 0 (default)

qsv enum data.csv

Add an incremental index column starting from 100 and incrementing by 10

qsv enum --start 100 --increment 10 data.csv

Add a uuid v4 column

qsv enum --uuid4 data.csv

Add a uuid v7 column

qsv enum --uuid7 data.csv

Add a constant column with the value "active"

qsv enum --constant active data.csv

Add a constant column with null values

qsv enum --constant "<NULL>" data.csv

Add a copy of the "username" column as "username_copy"

qsv enum --copy username data.csv

Add a hash column with the hash of columns "first_name" and "last_name"

qsv enum --hash first_name,last_name data.csv

Add a hash column with the hash of all columns except an existing "hash" column

qsv enum --hash 1- data.csv

Add a hash column with the hash of all columns except "id" and "uuid" columns

qsv enum --hash "!id,!uuid" data.csv

Add a hash column with the hash of all columns that match the regex "record|name|address"

qsv enum --hash "/record|name|address/" data.csv

For more examples, see tests.

Usage ↩

qsv enum [options] [<input>]
qsv enum --help

Enum Options ↩

Option	Type	Description	Default
‑c, ‑‑new‑column	string	Name of the column to create. Will default to "index".
‑‑start	string	The value to start the enumeration from. Only applies in Increment mode. (default: 0)
‑‑increment	string	The value to increment the enumeration by. Only applies in Increment mode. (default: 1)
‑‑constant	string	Fill a new column with the given value. Changes the default column name to "constant" unless overridden by --new-column. To specify a null value, pass the literal "".
‑‑copy	string	Name of a column to copy. Changes the default column name to "{column}_copy" unless overridden by --new-column.
‑‑uuid4	flag	When set, the column will be populated with uuids (v4) instead of the incremental identifier. Changes the default column name to "uuid4" unless overridden by --new-column.
‑‑uuid7	flag	When set, the column will be populated with uuids (v7) instead of the incremental identifier. uuid v7 is a time-based uuid and is monotonically increasing. See https://buildkite.com/blog/goodbye-integers-hello-uuids Changes the default column name to "uuid7" unless overridden by --new-column.
‑‑hash	string	Create a new column filled with the hash of the given column/s. Use "1-" to hash all columns. Changes the default column name to "hash" unless overridden by --new-column. Will remove an existing "hash" column if it exists.

Common Options ↩

Option	Type	Description	Default
‑h, ‑‑help	flag	Display this message
‑o, ‑‑output	string	Write output to instead of stdout.
‑n, ‑‑no‑headers	flag	When set, the first row will not be interpreted as headers.
‑d, ‑‑delimiter	string	The field delimiter for reading CSV data. Must be a single character. (default: ,)

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Source: src/cmd/enumerate.rs | Table of Contents | README