Case Transform
Note
Transforms are a part of the underlying language, which is not directly accessible to users. This content is maintained for reference purposes only. For more information on the user-accessible equivalent to transforms, see Transformation Reference.
Performs conditional transformation of data with a single statement using if-then-else logic or with multiple statements using case logic. Results are generated in a new column.
Note
If you are running your job on Spark, avoid creating single conditional transformations with deeply nested sets of conditions. On Spark, these jobs can time out, and deeply nested steps can be difficult to debug. Instead, break up your nesting into smaller conditional transformations of multiple steps.
There are function equivalents to this transformation:
Basic Usage
Example - if/then/else
This example illustrates a single if/then/else construction:
case if: testScore >= 60 then: 'yes' else: 'no' as: 'passedTest'
Output: If a value in the testScore is greater than or equal to 60, a value of yes is written into the new passedTest column. Otherwise, a value of no is written.
Example - Case (single column)
This example shows how to step through a sequence of case tests applied to a single column.
case col: custName colCases: ['Big Co',0.2],['Little Guy Ltd',0.05] default: 0 as: 'discountRate'
Output: Checks names in the custName column and writes discount values based on exact matches of values in the column:
custName value | discountRate |
|---|---|
Big Co | 0.2 |
Little Guy Ltd | 0.05 |
default (if no matches) | 0 |
Example - Case (custom conditions)
The following example illustrates how to construct case transforms with multiple independent conditions. Tests can come from arbitrary columns and expressions.
The first case is tested:
If
true, then the listed value is written to the new column.If
false, then the next case is tested.
If none of the stated cases evaluates to
true, then the default value is written.
case cases: [totalOrdersQ3 < 10, true], [lastOrderDays > 60, true] default: false as: 'sendCheckinEmail'
Output: If the total orders in Q3 < 10 OR the last order was placed more than 60 days ago, then write true in the sendCheckinEmail. Otherwise, write false.
Logic | Test | SendCheckinEmail |
|---|---|---|
if | totalOrdersQ3 < 10 | true |
if above is false | lastOrderDays > 60 | true |
if above is false | write default | false |
Syntax and Parameters
case [if: if_expression] [then:'str_if_true'] [else:'str_if_false] [col:col1] [colCases: [[Match1,Val1]],[[Match2,Val2]] [cases: [[Exp3,Val3]],[[Exp4,Val4]] [default:default_val] as: 'new_column_name'
Token | Required? | Data Type | Description |
|---|---|---|---|
case | Y | transform | Name of the transform |
if | N | string | (For single if/then/else) Expression that is tested must evaluate to |
then | N | string | (For single if/then/else) Value written to the new column if the if expression is |
else | N | string | (For single if/then/else) Value written to the new column if the if expression is |
col | N | string | (For single-column case) Name of column whose values are to be tested. |
colCases | N | comma-separated arrays | (For single-column case) Matrix of string-value pairs:
|
cases | N | comma-separated arrays | (For custom conditions case) Matrix of expression-value pairs:
|
default | N | any | (For single-column case and custom condition case) If no matches are made, this value is written to the new column. |
as | Y | string | Name of the new column where results are written. |
For more information on syntax standards, see Language Documentation Syntax Notes.
if
For if-then-else condition types, this value is an expression to test. Expression must evaluate to true or false.
Usage Notes:
Required? | Data Type |
|---|---|
Required for if-the-else condition type | String (expression) |
then
For if-then-else condition types, this value is a literal value to write in the output column if the expression evaluates to true.
Usage Notes:
Required? | Data Type |
|---|---|
Required for if-the-else condition type | String or other literal type |
else
For if-then-else condition types, this value is a literal value to write in the output column if the expression evaluates to false.
Usage Notes:
Required? | Data Type |
|---|---|
Required for if-the-else condition type | String or other literal type |
col
For single-case condition types, this value identifies the column to test.
Usage Notes:
Required? | Data Type |
|---|---|
Required for single-case condition type | String (column name) |
colCases
For single-case condition types, this parameter contains a comma-separated set of two-value arrays.
Array value 1: A literal value to match in the specified column.
Array value 2: If the value is matched, this value is written into the output column.
You can specify one or more cases as comma-separated two-value arrays.
Usage Notes:
Required? | Data Type |
|---|---|
Required for single-case condition type | Array (comma-separated list) |
cases
For multi-case condition types, this parameter contains a comma-separated set of two-value arrays.
Array value 1: An expression to test, which must evaluate to
trueorfalse.Array value 2: If the value is matched, this value is written into the output column.
You can specify one or more cases as comma-separated two-value arrays.
Usage Notes:
Required? | Data Type |
|---|---|
Required for single-case condition type | Array (comma-separated list) |
default
For single-case and multi-case condition types, this parameter defines the value to write in the new column if none of the cases yields a true result.
Usage Notes:
Required? | Data Type |
|---|---|
Required for single-case condition type | Literal of any data type |
as
Name of the new column that is being generated. If the as parameter is not specified, a default name is used.
Usage Notes:
Required? | Data Type |
|---|---|
Yes | String (column name) |
Examples
Tip
For additional examples, see Common Tasks.
See above.