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nushell/docs/commands/histogram.md
Joseph T. Lyons 3239e5055c
Added a count column on the histogram command (#1853) 
* Adding iniitial draft for the addition of the count column on the histogram command

* Update histogram documentation

* Add count column test to histogram command

* Fix error in histogram documentation
2020-05-20 18:02:36 +12:00

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histogram

Creates a new table with a histogram based on the column name passed in.

Syntax: histogram <column_name> ...args

Parameters

  • <column-name>: name of the column to graph by
  • args: column name to give the histogram's frequency column

Examples

Let's say we have this file random_numers.csv which contains 50 random numbers.

Note: The input doesn't have to be numbers it works on strings too. Try it out.

> open random_numbers.csv
────┬────────────────
 #  │ random numbers
────┼────────────────
  0 │              1
  1 │              2
  2 │              2
        ...
 47 │              5
 48 │              5
 49 │              1
────┴────────────────

If we now want to see how often the different numbers were generated, we can use the histogram function:

> open random_numbers.csv | histogram "random numbers"
───┬────────────────┬───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────
 # │ random numbers │ count │ frequency
───┼────────────────┼───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────
 0 │ 0              │     1 │ ******
 1 │ 1              │    15 │ ****************************************************************************************************
 2 │ 2              │    10 │ ******************************************************************
 3 │ 3              │     7 │ **********************************************
 4 │ 4              │     9 │ ************************************************************
 5 │ 5              │     8 │ *****************************************************
───┴────────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────

We can also set the name of the second column or sort the table:

> open random_numbers.csv | histogram "random numbers" probability
───┬────────────────┬───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────
 # │ random numbers │ count │ probability
───┼────────────────┼───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────
 0 │ 0              │     1 │ ******
 1 │ 1              │    15 │ ****************************************************************************************************
 2 │ 2              │    10 │ ******************************************************************
 3 │ 3              │     7 │ **********************************************
 4 │ 4              │     9 │ ************************************************************
 5 │ 5              │     8 │ *****************************************************
───┴────────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────


> open random_numbers.csv | histogram "random numbers" probability | sort-by probability
───┬────────────────┬───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────
 # │ random numbers │ count │ probability
───┼────────────────┼───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────
 0 │ 0              │     1 │ ******
 1 │ 3              │     7 │ **********************************************
 2 │ 5              │     8 │ *****************************************************
 3 │ 4              │     9 │ ************************************************************
 4 │ 2              │    10 │ ******************************************************************
 5 │ 1              │    15 │ ****************************************************************************************************
───┴────────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────

Of course, histogram operations are not restricted to just analyzing numbers in files, you can also analyze your directories

> ls -fa | histogram type | sort-by count
───┬─────────┬───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────
 # │ type    │ count │ frequency
───┼─────────┼───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────
 0 │ Symlink │     8 │ *****************
 1 │ File    │     9 │ ********************
 2 │ Dir     │    45 │ ****************************************************************************************************
───┴─────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────