Filter Transform

注記

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.

Removes or keeps the matching rows of data, based on a condition that you specify or a custom formula that you apply.

Basic Usage

You can filter your dataset based on the following condition types:

Example - is missing

filter missing: qty action: Drop

Output: Deletes all rows in which the value in the qty column is missing.

Example - is mismatched

filter col: CoName mismatched: 'String' action: Drop

Output: Deletes all rows in which the value in the CoName column does not match the String data type.

Example - is exactly

filter col: basic exactly: find(basic, '545', true, 1) == 8 action: Keep

Output: Keeps all rows where 545 appears at the eighth character in the basic column.

Example - is one of

filter col: zipCode oneOf: '94104','94105' action: Keep

Output: Keeps all rows in which the value of the zipCode column is either 94104 or 94105 and deletes all other rows in the dataset.

Example - Less than (or equal to)

filter col: row_number lessThanEqual: 5 action: Keep

Output: Keeps all rows in the dataset where the value in the row_number column is less than or equal to 5. All other rows are deleted.

Example - Greater than (or equal to)

filter col: row_number greaterThanEqual: 10 action: Drop

Output: Deletes all rows in the dataset where the value in row_number is greater than or equal to 10.

Example - Is Between

filter col: row_number greaterThan: 5 lessThanEqual: 15 action: Keep

Output: Keeps all rows where the row_number value is greater than 5 or less than or equal to 15. All other rows are deleted.

Example - Contains

filter col: phoneNum contains: `\({digit}{3}\)` action: Keep

Output: Keeps all rows where the phoneNum value contains a three-digit pattern surrounded by parentheses (XXX). All other rows are deleted.

Example - Starts with

filter col: phoneNum startsWith: '(981)' action: Keep

Output: Keeps all rows where the phoneNum value begins with (981). All other rows are deleted.

Example - Ends with

filter col: zipCode endsWith: `\-{digit}{4}` action: Drop

Output: Deletes all rows where the zipCode value ends with a four-digit extension.

Example - custom formula

filter row: (row_number >= 25 && firstName == 'Steve') action: Keep

Output: Keeps all rows where the row_number value is greater than or equal to 25 and the firstName value is Steve. All other rows are deleted.

Syntax and Parameters

filter col:column_ref type: 'filter_str' [missing: column_ref] [exactly: expression_ref] [mismatched: 'data_type_str'] [exactly: expression] [oneOf: 'string_1','string_2'] [lessthan | lessThanEqual: numVal] [greaterthan | greaterThanEqual: numVal] [contains: string_or_pattern] [startsWith|endsWith: string_or_pattern] action: [Drop|Keep]

Token	Required?	Data Type	Description
filter	Y	transform	Name of the transform
type	Y	string	String value representing the type of filtering to perform.
row	N	string	Expression identifying the row or rows to filter. If expression evaluates to`true`for a row, the row is either kept or deleted.
col	N	string	Name of the column or expression for columns to delete
missing	N	string	Name of column to evaluate for missing values.
mismatched	N	string	String literal for the data type to check for mismatches.
exactly	N	string	String literal, Wrangle , or regular expression that evaluates to an exact match for a row value in the specified column.
oneOf	N	string	List of string literals, any of which can be matched.
lessThan or lessThanEqual	N	integer, decimal, or expression	Integer or decimal literal or expression evaluating to numeric value below which results in a match. Can also match on the specified expression exactly. Parameter is also used for the Between condition type.
greaterThan or greaterThanEqual	N	integer, decimal, or expression	Integer or decimal literal or expression evaluating to numeric value above which results in a match. Can also match on the specified expression exactly. Parameter is also used for the Between condition type.
contains	N	string	String literal, Wrangle, or regular expression to be matches somewhere within the specified column values.
startsWith	N	string	String literal, Wrangle , or regular expression to match the beginnings of the values in the specified column.
endsWith	N	string	String literal, Wrangle, or regular expression to match the endings of the values in the specified column.
action	Y	string	`Drop` or `Keep` the listed columns

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

type

String literal for the type of filtering to perform. For more information on these string literal values, see Valid Data Type Strings.

Usage Notes:

Required?	Data Type
Yes	String literal that corresponds to one of the supported data type values

row

Expression to identify the row or rows on which to perform the transform. Expression must evaluate to true or false.

Examples:

Expression	Description
Score >= 50	`true` if the value in the `Score` column is greater than 50.
LEN(LastName) > 8	`true` if the length of the value in the `LastName` column is greater than 8.
ISMISSING([Title])	`true` if the row value in the `Title` column is missing.
ISMISMATCHED(Score,['Integer'])	`true` if the row value in the `Score` column is mismatched against the Integer data type.

Example:

delete row: (lastContactDate < 01/01/2010 || status == 'Inactive')

Output: Deletes any row in the dataset where the lastContactDate is before January 1, 2010 or the status is Inactive.

Usage Notes:

Required?	Data Type
Yes	Expression that evaluates to `true` or `false`

col

Identifies the column or columns to which to apply the transform. You can specify one column or more columns.

Usage Notes:

Required?	Data Type
Yes	String (column name)

missing

For the Is Missing condition type, this value specifies the column to check for missing values.

Usage Notes:

Required?	Data Type
Required for Is Missing condition type only	String (column name)

mismatched

For the Mismatched condition type, this value specifies string for the data type identifier value to check for mismatches. For more information, see Valid Data Type Strings.