namespaces.EraExpr

era_pl.namespaces.EraExpr(expr)

Custom expression helpers used throughout the Polars-facing API.

Methods

Name Description
div_if_pos Divide by other only when the denominator is strictly positive.
ntile Assign observations to n approximately equal-sized buckets.
truncate Set values outside type-2 quantile cutoffs to null.
winsorize Clip values to type-2 quantile cutoffs, following farr::winsorize().

div_if_pos

era_pl.namespaces.EraExpr.div_if_pos(other)

Divide by other only when the denominator is strictly positive.

The result is null when the denominator is zero, negative, or null. This is convenient for ratio construction in accounting-style pipelines where non-positive denominators are usually treated as invalid.

ntile

era_pl.namespaces.EraExpr.ntile(n)

Assign observations to n approximately equal-sized buckets.

This mirrors the common SQL/R ntile idea and is typically used with .over(...) to create within-group deciles, quintiles, and similar ranked portfolios. Null values remain null and are excluded when bucket sizes are calculated.

truncate

era_pl.namespaces.EraExpr.truncate(prob=0.01, p_low=None, p_high=None)

Set values outside type-2 quantile cutoffs to null.

Argument resolution matches :meth:winsorize.

winsorize

era_pl.namespaces.EraExpr.winsorize(prob=0.01, p_low=None, p_high=None)

Clip values to type-2 quantile cutoffs, following farr::winsorize().

Argument handling mirrors the R helper:

  • winsorize(prob=0.01) is equivalent to winsorize(p_low=0.01, p_high=0.99).
  • If p_low and/or p_high are supplied, those explicit cutoffs are used in preference to the defaults implied by prob.
  • If prob=None, only the explicitly supplied side(s) are applied, so one-sided winsorization is possible.