EXAMPLE - ARRAYLEN and ARRAYELEMENTAT Functions
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:
Flag the students who have not taken four tests.
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 | |
|---|---|
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 | |
|---|---|
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 | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | ARRAYELEMENTAT(Scores,0) |
Parameter: New column name | 'highestScore' |
Transformation Name | |
|---|---|
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 | |
|---|---|
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 |