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Filter

Split data into rows that match or don't match a condition.

Sockets​

SocketDirectionDescription
inputInputData to filter
T (output-true)OutputRows where condition is true
F (output-false)OutputRows where condition is false

Configuration​

FieldRequiredDescription
Filter ExpressionYesPolars expression that returns true/false for each row
Using the Expression Editor

The expression editor provides autocomplete for column names and Polars methods. Press Tab after typing pl.col(" to see your columns, or press . + Tab after any expression to see available methods. See Expression Basics for a step-by-step guide.

How It Works​

The Filter tool evaluates your expression against each row:

  • Rows where the expression is true go to the T output
  • Rows where the expression is false go to the F output

Both outputs are always available - you can wire to either or both depending on your needs.

Expression Examples​

Simple Comparisons​

# Rows where age is over 18
pl.col("age") > 18

# Rows where status is "active"
pl.col("status") == "active"

# Rows where price is between 10 and 100
(pl.col("price") >= 10) & (pl.col("price") <= 100)

Multiple Conditions​

# AND - all conditions must be true
(pl.col("status") == "active") & (pl.col("country") == "US")

# OR - any condition can be true
(pl.col("status") == "active") | (pl.col("status") == "pending")

String Matching​

# Contains substring
pl.col("email").str.contains("@gmail.com")

# Case-insensitive contains
pl.col("name").str.to_lowercase().str.contains("john")

# Starts with
pl.col("product_code").str.starts_with("ABC")

Null Handling​

# Filter out nulls
pl.col("value").is_not_null()

# Keep only nulls
pl.col("value").is_null()

Negation​

# NOT - invert a boolean column
~pl.col("is_deleted")

# NOT - invert a condition
~(pl.col("status") == "inactive")

Common Patterns​

Keeping Only Matching Rows​

Wire only the T output to downstream tools - the F output is discarded.

Removing Matching Rows​

Wire only the F output - the rows that DON'T match go forward.

Splitting Data​

Wire both outputs to different downstream paths to process matching and non-matching rows separately.

Notes​

  • Empty expression: If no expression is provided, all rows go to T output
  • Invalid expression: Configuration error is shown, tool won't execute
  • Schema unchanged: Filter doesn't add, remove, or rename columns - only filters rows