LISTSTDEV Function
Computes the standard deviation of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type.
When this function is invoked, all of the values in the input array are passed to the corresponding columnar function. Some restrictions may apply. See STDEV Function.
Wrangle vs. SQL: This function is part of Wrangle, a proprietary data transformation language. Wrangle is not SQL. For more information, see Wrangle Language.
Basic Usage
Literal example:
liststdev([0,0,2,4,6,8,10,12,14,16,18,20])
Output: Returns the standard deviation of all values in the literal array: 6.952217872.
Column example:
liststdev(myArray)
Output: Generates an output column containing the standard deviation of all values in the arrays of the myArray column.
Syntax and Arguments
liststdev(array_ref)
Argument | Required? | Data Type | Description |
|---|---|---|---|
array_ref | Y | Array | Array literal, reference to column containing arrays, or function returning an array |
For more information on syntax standards, see Language Documentation Syntax Notes.
array_ref
Reference to an array can be an array literal, function returning an array, or a single column containing arrays.
If the input is not a valid numeric array, null values are returned.
Non-numerical values within an input array are not factored in the computation.
Multiple columns and wildcards are not supported.
Usage Notes:
Required? | Data Type | Example Value |
|---|---|---|
Yes | Array | myArray |
Examples
Suggerimento
For additional examples, see Common Tasks.
Example - Math functions for lists (arrays)
This example describes how to generate random array (list) data and then to apply statistical functions specifically created for arrays.
Functions:
Item | Description |
|---|---|
LISTSUM Function | Computes the sum of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTMIN Function | Computes the minimum of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTMAX Function | Computes the maximum of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTAVERAGE Function | Computes the average of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTVAR Function | Computes the variance of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTSTDEV Function | Computes the standard deviation of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
LISTMODE Function | Computes the most common value of all numeric values found in input array. Input can be an array literal, a column of arrays, or a function returning an array. Input values must be of Integer or Decimal type. |
Also:
Item | Description |
|---|---|
RANGE Function | Computes an array of integers, from a beginning integer to an end (stop) integer, stepping by a third parameter. |
RAND Function | The |
ROUND Function | Rounds input value to the nearest integer. Input can be an Integer, a Decimal, a column reference, or an expression. Optional second argument can be used to specify the number of digits to which to round. |
Source:
For this example, you can generate some randomized data using the following steps. First, you need to seed an array with a range of values using the RANGE function:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | RANGE(5, 50, 5) |
Parameter: New column name | 'myArray1' |
Then, unpack this array, so you can add a random factor:
Transformation Name | |
|---|---|
Parameter: Column | myArray1 |
Parameter: Paths to elements | '[0]', '[1]', '[2]', '[3]', '[4]', '[5]', '[6]', '[7]', '[8]', '[9]' |
Parameter: Remove elements from original | true |
Parameter: Include original column name | true |
Add the randomizing factor. Here, you are adding randomization around individual values: x-1 < x < x+4.
Transformation Name | |
|---|---|
Parameter: Columns | myArray1_0~myArray1_8 |
Parameter: Formula | IF(RAND() > 0.5, $col + (5 * RAND()), $col - RAND()) |
To make the numbers easier to manipulate, you can round them to two decimal places:
Transformation Name | |
|---|---|
Parameter: Columns | myArray1_0~myArray1_8 |
Parameter: Formula | ROUND($col, 2) |
Renest these columns into an array:
Transformation Name | |
|---|---|
Parameter: Columns | myArray1_0, myArray1_1, myArray1_2, myArray1_3, myArray1_4, myArray1_5, myArray1_6, myArray1_7, myArray1_8 |
Parameter: Nest columns to | Array |
Parameter: New column name | 'myArray2' |
Delete the unused columns:
Transformation Name | |
|---|---|
Parameter: Columns | myArray1_0~myArray1_8,myArray1 |
Parameter: Action | Delete selected columns |
Your data should look similar to the following:
myArray2 |
|---|
["8.29","9.63","14.63","19.63","24.63","29.63","34.63","39.63","44.63"] |
["8.32","14.01","19.01","24.01","29.01","34.01","39.01","44.01","49.01"] |
["4.55","9.58","14.58","19.58","24.58","29.58","34.58","39.58","44.58"] |
["9.22","14.84","19.84","24.84","29.84","34.84","39.84","44.84","49.84"] |
["8.75","13.36","18.36","23.36","28.36","33.36","38.36","43.36","48.36"] |
["8.47","14.76","19.76","24.76","29.76","34.76","39.76","44.76","49.76"] |
["4.93","9.99","14.99","19.99","24.99","29.99","34.99","39.99","44.99"] |
["4.65","14.98","19.98","24.98","29.98","34.98","39.98","44.98","49.98"] |
["7.80","14.62","19.62","24.62","29.62","34.62","39.62","44.62","49.62"] |
["9.32","9.96","14.96","19.96","24.96","29.96","34.96","39.96","44.96"] |
Transformation:
These steps demonstrate the individual math functions that you can apply to your list data without unnesting it:
Nota
The NUMFORMAT function has been wrapped around each list function to account for any floating-point errors or additional digits in the results.
Sum of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTSUM(myArray2), '#.##') |
Parameter: New column name | 'arraySum' |
Minimum of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTMIN(myArray2), '#.##') |
Parameter: New column name | 'arrayMin' |
Maximum of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTMAX(myArray2), '#.##') |
Parameter: New column name | 'arrayMax' |
Average of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTAVERAGE(myArray2), '#.##') |
Parameter: New column name | 'arrayAvg' |
Variance of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTVAR(myArray2), '#.##') |
Parameter: New column name | 'arrayVar' |
Standard deviation of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTSTDEV(myArray2), '#.##') |
Parameter: New column name | 'arrayStDv' |
Mode (most common value) of all values in the array (list):
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | NUMFORMAT(LISTMODE(myArray2), '#.##') |
Parameter: New column name | 'arrayMode' |
Results:
Results for the first four math functions:
myArray2 | arrayAvg | arrayMax | arrayMin | arraySum |
|---|---|---|---|---|
["8.29","9.63","14.63","19.63","24.63","29.63","34.63","39.63","44.63"] | 25.04 | 44.63 | 8.29 | 225.33 |
["8.32","14.01","19.01","24.01","29.01","34.01","39.01","44.01","49.01"] | 28.93 | 49.01 | 8.32 | 260.4 |
["4.55","9.58","14.58","19.58","24.58","29.58","34.58","39.58","44.58"] | 24.58 | 44.58 | 4.55 | 221.19 |
["9.22","14.84","19.84","24.84","29.84","34.84","39.84","44.84","49.84"] | 29.77 | 49.84 | 9.22 | 267.94 |
["8.75","13.36","18.36","23.36","28.36","33.36","38.36","43.36","48.36"] | 28.4 | 48.36 | 8.75 | 255.63 |
["8.47","14.76","19.76","24.76","29.76","34.76","39.76","44.76","49.76"] | 29.62 | 49.76 | 8.47 | 266.55 |
["4.93","9.99","14.99","19.99","24.99","29.99","34.99","39.99","44.99"] | 24.98 | 44.99 | 4.93 | 224.85 |
["4.65","14.98","19.98","24.98","29.98","34.98","39.98","44.98","49.98"] | 29.39 | 49.98 | 4.65 | 264.49 |
["7.80","14.62","19.62","24.62","29.62","34.62","39.62","44.62","49.62"] | 29.42 | 49.62 | 7.8 | 264.76 |
["9.32","9.96","14.96","19.96","24.96","29.96","34.96","39.96","44.96"] | 25.44 | 44.96 | 9.32 | 229 |
Results for the statistical functions:
myArray2 | arrayMode | arrayStDv | arrayVar |
|---|---|---|---|
["8.29","9.63","14.63","19.63","24.63","29.63","34.63","39.63","44.63"] | 12.32 | 151.72 | |
["8.32","14.01","19.01","24.01","29.01","34.01","39.01","44.01","49.01"] | 13.03 | 169.78 | |
["4.55","9.58","14.58","19.58","24.58","29.58","34.58","39.58","44.58"] | 12.92 | 166.8 | |
["9.22","14.84","19.84","24.84","29.84","34.84","39.84","44.84","49.84"] | 13.02 | 169.46 | |
["8.75","13.36","18.36","23.36","28.36","33.36","38.36","43.36","48.36"] | 12.84 | 164.95 | |
["8.47","14.76","19.76","24.76","29.76","34.76","39.76","44.76","49.76"] | 13.14 | 172.56 | |
["4.93","9.99","14.99","19.99","24.99","29.99","34.99","39.99","44.99"] | 12.92 | 166.93 | |
["4.65","14.98","19.98","24.98","29.98","34.98","39.98","44.98","49.98"] | 13.9 | 193.16 | |
["7.80","14.62","19.62","24.62","29.62","34.62","39.62","44.62","49.62"] | 13.23 | 175.08 | |
["9.32","9.96","14.96","19.96","24.96","29.96","34.96","39.96","44.96"] | 12.21 | 149.17 |
Since all values are unique within an individual array, there is no most common value in any of them, which yields empty values for the arrayMode column.