RAND Function
The RAND function generates a random real number between 0 and 1. The function accepts an optional integer parameter, which causes the same set of random numbers to be generated with each job execution.
This function generates values of Decimal type with fifteen digits of precision after the decimal point. If you want to see all digits in the generated value, you might need to apply a different number format. See NUMFORMAT Function.
New random numbers are generated within the browser, after each browser refresh, and between subsequent job executions.
Optionally, you can insert an integer as a parameter.
When this value is present, this seed value is used as part of the random number generator such that its output is a set of pseudo-random values, which are consistent between job executions.
When the browser is refreshed, the random numbers remain consistent when the seed value is present.
This value must be a valid literal Integer value.
If none is provided, a seed is generated based on the system timestamp.
Column references or functions returning Integer values are not supported.
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
Example:
rand()
Output: For each row, generate a random number between 0 and 1 in the new random function.
Example with seed value:
rand(2)
Output: For each row, generate a random number between 0 and 1 in the new random function. The generated random set of random values are consistent between job executions and are, in part, governed by the seed value 2.
Syntax and Arguments
There are no arguments for this function.
rand([int_value])
Argument | Required? | Data Type | Description |
|---|---|---|---|
int_value | N | integer | Integer literal |
For more information on syntax standards, see Language Documentation Syntax Notes.
int_value
Optional Integer literal that is used to generate random numbers. Use of a seed value ensures consistency of output between job executions.
This value must be a valid literal Integer value.
Literal numeric values should not be quoted. Quoted values are treated as strings.
Multiple columns and wildcards are not supported.
Usage Notes:
Required? | Data Type | Example Value |
|---|---|---|
No | Integer literal | 14 |
Examples
Astuce
For additional examples, see Common Tasks.
Example - Random values
In the following example, the random column is generated by the RAND function:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | rand() |
Parameter: New column name | 'random' |
source | random |
|---|---|
A |
|
B |
|
C |
|
D |
|
Example - Type check functions
The RAND function is typically used to introduce randomness of some kind in your data. In the following example, it is used to perform sampling within your wider dataset. Source:
You want to extract a random sample of 20% of your set of orders for further study:
OrderId | Qty | ProdId |
|---|---|---|
1001 | 30 | Widgets |
1002 | 10 | Big Widgets |
1003 | 5 | Big Widgets |
1004 | 40 | Widgets |
1005 | 80 | Tiny Widgets |
1006 | 20 | Widgets |
1007 | 100 | Tiny Widgets |
Transformation:
You can use the following transform to generate a random integer from one to 10:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | round(rand() * 10) |
Parameter: New column name | 'random' |
You can now use the following transform to keep only the rows that contain random values that are in the top 20%, where the value is 9 or 10:
Transformation Name | |
|---|---|
Parameter: Condition | Custom formula |
Parameter: Type of formula | Custom single |
Parameter: Condition | (random > 8) |
Parameter: Action | Keep matching rows |
Results:
Note
Since the results are randomized, your results might vary.
OrderId | Qty | ProdId | random |
|---|---|---|---|
1005 | 80 | Tiny Widgets | 9 |
1007 | 100 | Tiny Widgets | 10 |