Contents Menu Expand Light mode Dark mode Auto light/dark, in light mode Auto light/dark, in dark mode Skip to content
pydiverse.transform
pydiverse.transform
  • Quickstart
  • Examples
    • Joining and Tables as Column namespaces
    • Aggregation functions
    • Window functions
    • Database testing
    • DuckDB, Polars, and Parquet
  • Table Backends
  • Database testing
  • Best Practices for describing tabular data transformations
    • Best Practices: Beware the flatfile & embrace working with entities
    • Best Practices: start sql, finish polars
  • API
    • Verbs
      • alias
      • arrange
      • ast_repr
      • build_query
      • collect
      • drop
      • export
      • filter
      • full_join
      • group_by
      • inner_join
      • join
      • left_join
      • mutate
      • name
      • rename
      • select
      • show
      • show_query
      • slice_head
      • summarize
      • ungroup
      • union
    • Column Operations
      • Arithmetic
        • +
        • -
        • *
        • /
        • - (unary)
        • + (unary)
        • //
        • %
      • Logical
        • &
        • ~
        • |
        • ^
        • any
        • all
        • is_in
        • is_not_null
        • is_null
        • fill_null
        • map
      • Comparison
        • ==
        • >=
        • >
        • <=
        • <
        • !=
        • is_inf
        • is_nan
        • is_not_inf
        • is_not_nan
        • is_not_null
        • is_null
      • Numerical
        • ** (pow)
        • abs
        • ceil
        • exp
        • floor
        • is_inf
        • is_nan
        • is_not_inf
        • is_not_nan
        • log
        • round
      • String
        • str.contains
        • str.ends_with
        • str.join
        • str.len
        • str.lower
        • str.replace_all
        • str.slice
        • str.starts_with
        • str.strip
        • str.to_date
        • str.to_datetime
        • str.upper
      • Datetime / Duration
        • dt.day
        • dt.day_of_week
        • dt.day_of_year
        • dt.hour
        • dt.microsecond
        • dt.millisecond
        • dt.minute
        • dt.month
        • dt.second
        • dt.year
        • dur.days
        • dur.hours
        • dur.microseconds
        • dur.milliseconds
        • dur.minutes
        • dur.seconds
      • Aggregation
        • count
        • all
        • any
        • max
        • mean
        • min
        • sum
        • str.join
      • Window
        • cum_sum
        • shift
        • dense_rank
        • rank
        • row_number
      • Sorting Markers
        • ascending
        • descending
        • nulls_first
        • nulls_last
      • Horizontal Aggregation
        • coalesce
        • count
        • all
        • any
        • max
        • min
        • sum
      • Conditional Logic
        • when
        • coalesce
        • map
      • Type Conversion
        • lit
        • cast
    • Backends / Export Targets
      • DuckDb
      • Pandas
      • Polars
      • SqlAlchemy
    • Types
      • Dtype
      • Bool
      • Date
      • Datetime
      • Decimal
      • Float
      • Float32
      • Float64
      • Int
      • Int8
      • Int16
      • Int32
      • Int64
      • String
      • UInt8
      • UInt16
      • UInt32
      • UInt64
    • Alignment
      • aligned
      • eval_aligned
    • Miscellaneous functions
      • verb
      • backend
      • is_sql_backed
      • transfer_col_references

Development

  • Changelog
  • 0.7.2 (2026-07-10)
  • 0.7.1 (2026-07-07)
  • License
Back to top
View this page
Edit this page

when¶

pydiverse.transform.when(
condition: ColExpr,
) → WhenClause[source]¶
Next
Type Conversion
Previous
Conditional Logic
Copyright © 2026, QuantCo, Inc
Made with Sphinx and @pradyunsg's Furo
On this page
  • when
    • pydiverse.transform.when()