forked from extern/nushell
223 lines
6.3 KiB
Markdown
223 lines
6.3 KiB
Markdown
# math
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Mathematical functions that generally only operate on a list of numbers (integers, decimals, bytes) and tables.
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Currently the following functions are implemented:
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* `math abs`: Returns absolute values of a list of numbers
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* `math avg`: Finds the average of a list of numbers or tables
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* `math ceil`: Applies the ceil function to a list of numbers
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* [`math eval`](math-eval.md): Evaluates a list of math expressions into numbers
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* `math floor`: Applies the floor function to a list of numbers
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* `math max`: Finds the maximum within a list of numbers or tables
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* `math median`: Finds the median of a list of numbers or tables
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* `math min`: Finds the minimum within a list of numbers or tables
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* `math mode`: Finds the most frequent element(s) within a list of numbers or tables
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* `math round`: Applies the round function to a list of numbers
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* `math stddev`: Finds the standard deviation of a list of numbers or tables
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* `math sum`: Finds the sum of a list of numbers or tables
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* `math product`: Finds the product of a list of numbers or tables
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* `math variance`: Finds the variance of a list of numbers or tables
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However, the mathematical functions like `min` and `max` are more permissive and also work on `Dates`.
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## Examples
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To get the average of the file sizes in a directory, simply pipe the size column from the ls command to the average command.
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### List of Numbers (Integers, Decimals, Bytes)
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```shell
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> ls
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# │ name │ type │ size │ modified
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────┼────────────────────┼──────┼──────────┼─────────────
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0 │ CODE_OF_CONDUCT.md │ File │ 3.4 KB │ 4 days ago
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1 │ CONTRIBUTING.md │ File │ 1.3 KB │ 4 days ago
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2 │ Cargo.lock │ File │ 106.3 KB │ 6 mins ago
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3 │ Cargo.toml │ File │ 4.6 KB │ 3 days ago
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4 │ LICENSE │ File │ 1.1 KB │ 4 days ago
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5 │ Makefile.toml │ File │ 449 B │ 4 days ago
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6 │ README.md │ File │ 16.0 KB │ 6 mins ago
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7 │ TODO.md │ File │ 0 B │ 6 mins ago
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8 │ assets │ Dir │ 128 B │ 4 days ago
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9 │ build.rs │ File │ 78 B │ 4 days ago
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10 │ crates │ Dir │ 672 B │ 3 days ago
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11 │ debian │ Dir │ 352 B │ 4 days ago
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12 │ docker │ Dir │ 288 B │ 4 days ago
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13 │ docs │ Dir │ 160 B │ 4 days ago
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14 │ features.toml │ File │ 632 B │ 4 days ago
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15 │ images │ Dir │ 160 B │ 4 days ago
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16 │ justfile │ File │ 234 B │ 3 days ago
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17 │ rustfmt.toml │ File │ 16 B │ 4 days ago
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18 │ src │ Dir │ 128 B │ 4 days ago
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19 │ target │ Dir │ 192 B │ 8 hours ago
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20 │ tests │ Dir │ 192 B │ 4 days ago
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```
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```shell
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> ls | get size | math avg
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───┬────────
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# │
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───┼────────
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0 │ 7.2 KB
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───┴────────
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```
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```shell
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> ls | get size | math min
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───┬─────
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# │
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───┼─────
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0 │ 0 B
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───┴─────
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```
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```shell
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> ls | get size | math max
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───┬──────────
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# │
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───┼──────────
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0 │ 113.6 KB
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───┴──────────
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```
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```shell
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> ls | get size | math median
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───┬───────
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# │
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───┼───────
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0 │ 320 B
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───┴───────
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```
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```shell
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> ls | get size | math sum
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───┬──────────
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# │
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───┼──────────
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0 │ 143.6 KB
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───┴──────────
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```
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```shell
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> echo [3 3 9 12 12 15] | math mode
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───┬────
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0 │ 3
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1 │ 12
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───┴────
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```
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```shell
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> echo [2 3 3 4] | math product
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72
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```
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```shell
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> echo [1 4 6 10 50] | math stddev
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18.1372
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```
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```shell
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> echo [1 4 6 10 50] | math variance
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328.96
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```
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```shell
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> echo [1.5 2.3 -3.1] | math ceil
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───┬────
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0 │ 2
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1 │ 3
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2 │ -3
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───┴────
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```
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```shell
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> echo [1.5 2.3 -3.1] | math floor
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───┬────
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0 │ 1
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1 │ 2
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2 │ -4
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───┴────
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```
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```shell
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> echo [1.5 2.3 -3.1] | math round
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───┬────
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0 │ 2
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1 │ 2
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2 │ -3
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───┴────
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```
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```shell
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> echo [1 -2 -3.0] | math abs
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───┬────────
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0 │ 1
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1 │ 2
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2 │ 3.0000
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───┴────────
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```
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### Dates
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```shell
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> ls | get modified | math min
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2020-06-09 17:25:51.798743222 UTC
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```
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```shell
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> ls | get modified | math max
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2020-06-14 05:49:59.637449186 UT
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```
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### Operations on tables
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```shell
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> pwd | split row / | size
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───┬───────┬───────┬───────┬────────────
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# │ lines │ words │ chars │ bytes
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───┼───────┼───────┼───────┼────────────
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0 │ 0 │ 1 │ 5 │ 5
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1 │ 0 │ 1 │ 11 │ 11
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2 │ 0 │ 1 │ 11 │ 11
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3 │ 0 │ 1 │ 4 │ 4
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4 │ 0 │ 2 │ 12 │ 12
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5 │ 0 │ 1 │ 7 │ 7
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───┴───────┴───────┴───────┴────────────
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```
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```shell
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> pwd | split row / | size | math max
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────────────┬────
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lines │ 0
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words │ 2
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chars │ 12
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bytes │ 12
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────────────┴────
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```
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```shell
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> pwd | split row / | size | math avg
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────────────┬────────
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lines │ 0.0000
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words │ 1.1666
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chars │ 8.3333
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bytes │ 8.3333
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────────────┴────────
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```
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To get the sum of the characters that make up your present working directory.
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```shell
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> pwd | split row / | size | get chars | math sum
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50
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```
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## Errors
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`math` functions are aggregation functions so empty lists are invalid
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```shell
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> echo [] | math avg
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error: Error: Unexpected: Cannot perform aggregate math operation on empty data
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```
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