COUNTDISTINCT Function
Generates the count of distinct values in a specified column, optionally counted by group. Generated value is of Integer type.
Nota
Empty string values are counted. Null values are not counted.
Nota
When added to a transformation, the function calculates the number of distinct values in the specified column, as displayed in the current sample. Counts are not applied to the entire dataset until you run the job. If you change your sample or run the job, the computed values for this function are updated. Transformations that change the number of rows in subsequent recipe steps do not affect the value for the already computed instance of COUNTDISTINCT.
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
countdistinct(name)
Output: Returns the count of distinct values in the name column.
Syntax and Arguments
countdistinct(function_col_ref) [group:group_col_ref] [limit:limit_count]
Argument | Required? | Data Type | Description |
|---|---|---|---|
function_col_ref | Y | string | Name of column to which to apply the function |
For more information on the group and limit parameter, see Pivot Transform.
function_col_ref
Name of the column from which to count values based on the grouping.
Literal values are not supported as inputs.
Multiple columns and wildcards are not supported.
Usage Notes:
Required? | Data Type | Example Value |
|---|---|---|
Yes | String (column reference) | myValues |
Examples
Suggerimento
For additional examples, see Common Tasks.
Example - Simple row count
This example demonstrates how to count the number of values and non-null values within a group.
Functions:
Item | Description |
|---|---|
COUNTA Function | Generates the count of non-null rows in a specified column, optionally counted by group. Generated value is of Integer type. |
COUNTDISTINCT Function | Generates the count of distinct values in a specified column, optionally counted by group. Generated value is of Integer type. |
Source:
In the following example, the seventh row is an empty string, and the eighth row is a null value.
rowId | Val |
|---|---|
r001 | val1 |
r002 | val1 |
r003 | val1 |
r004 | val2 |
r005 | val2 |
r006 | val3 |
r007 | (empty) |
r008 | (null) |
Transformation:
Apply a COUNTA function on the source column:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | COUNTA(Val) |
Parameter: New column name | 'fctnCounta' |
Apply a COUNTDISTINCT function on the source:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | COUNTDISTINCT(Val) |
Parameter: New column name | 'fctnCountdistinct' |
Results:
Below, both functions count the number of values in the column, with COUNTDISTINCT counting distinct values only. The empty value for r007 is counted by both functions.
rowId | Val | fctnCountdistinct | fctnCounta |
|---|---|---|---|
r001 | val1 | 4 | 7 |
r002 | val1 | 4 | 7 |
r003 | val1 | 4 | 7 |
r004 | val2 | 4 | 7 |
r005 | val2 | 4 | 7 |
r006 | val3 | 4 | 7 |
r007 | (empty) | 4 | 7 |
r008 | (null) | 4 | 7 |