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ARRAYELEMENTAT Function

Computes the 0-based index value for an array element in the specified column, array literal, or function that returns an array.

  • This function calculates based on the outer layer of an array. If your array is nested, the count of inner elements is not factored.

  • If a row contains a missing array, the returned value is 0. If it contains a value that is not recognized as an array, the returned value is null.

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

Array literal reference example:

arrayelementat([A,B,C,D],2)

Output: Returns the third value in the array, which is C.

Column reference example:

arrayelementat(myArrays,9)

Output: Returns the tenth element of the arrays listed in the myArrays column.

Array function example:

arrayelementat(concat([colA,colB]),3)

Output: Returns the fourth element of the concatenated array.

Syntax and Arguments

arrayelementat(array_ref,int_index_ref)

Argument

Required?

Data Type

Description

array_ref

Y

string

Name of Array column, Array literal, or function returning an Array to apply to the function

int_index_ref

Y

integer (non-negative)

Index value for the array element to return. Value can be Integer literal, column containing Integer values, or function returning an Integer.

For more information on syntax standards, see Language Documentation Syntax Notes.

array_ref

Name of the array column, array literal, or function returning an array whose elements you want to return.

  • Multiple columns and wildcards are not supported.

Usage Notes:

Required?

Data Type

Example Value

Yes

String (column reference or function) or array literal

myArray1

int_index_ref

Non-negative integer value representing the index value of the array element to return. Value can be Integer literal, column containing Integer values, or function returning an Integer.

  • Value must a non-negative integer. If the value is 0, then the first element of the array is returned.

  • If this value is greater than the length of the string, then a null value is returned.

Usage Notes:

Required?

Data Type

Example Value

Yes

Integer (non-negative)

5

Examples

Astuce

For additional examples, see Common Tasks.

Example - Student progress across tests

This example illustrates how to return n-based number of elements in an array.

Functions:

Item

Description

ARRAYLEN Function

Computes the number of elements in the arrays in the specified column, array literal, or function that returns an array.

ARRAYELEMENTAT Function

Computes the 0-based index value for an array element in the specified column, array literal, or function that returns an array.

ARRAYSORT Function

Sorts array values in the specified column, array literal, or function that returns an array in ascending or descending order.

Source:

Here are some student test scores. Individual scores are stored in the Scores column. You want to:

  1. Flag the students who have not taken four tests.

  2. Compute the range in scores for each student.

LastName

FirstName

Scores

Allen

Amanda

[79, 83,87,81]

Bell

Bobby

[85, 92, 94, 98]

Charles

Cameron

[88,81,85]

Dudley

Danny

[82,88,81,77]

Ellis

Evan

[91,93,87,93]

Transformation:

First, you want to flag the students who did not take all four tests:

Transformation Name

New formula

Parameter: Formula type

Single row formula

Parameter: Formula

IF(ARRAYLEN(Scores) < 4,"incomplete","")

Parameter: New column name

'Error'

This test flags Cameron Charles only.

The following transform sorts the array values in highest to lowest score:

Transformation Name

Edit column with formula

Parameter: Columns

Scores

Parameter: Formula

ARRAYSORT(Scores, 'descending')

The following transforms extracts the first (highest) and last (lowest) value in each student's test scores, provided that they took four tests:

Transformation Name

New formula

Parameter: Formula type

Single row formula

Parameter: Formula

ARRAYELEMENTAT(Scores,0)

Parameter: New column name

'highestScore'

Transformation Name

New formula

Parameter: Formula type

Single row formula

Parameter: Formula

ARRAYELEMENTAT(Scores,3)

Parameter: New column name

'lowestScore'

Astuce

You could also generate the Error column when the Scores4 column contains a null value. If no value exists in the array for the ARRAYELEMENTAT function, a null value is returned, which would indicate in this case an insufficient number of elements (test scores).

You can now track change in test scores:

Transformation Name

New formula

Parameter: Formula type

Single row formula

Parameter: Formula

SUBTRACT(highestScore,lowestScore)

Parameter: New column name

'Score_range'

Results:

LastName

FirstName

Scores

Error

lowestScore

highestScore

Score_range

Allen

Amanda

[87,83,81,79]

79

87

8

Bell

Bobby

[98,94,92,85]

85

98

13

Charles

Cameron

[88,85,81]

incomplete

88

Dudley

Danny

[88,82,81,77]

77

88

11

Ellis

Evan

[93,93,91,87]

87

93

6