Describe for a Date, Datetime, Time or Duration column: each statistic a value of the
column’s own type, written as the table writes it; None for a null.
The most values Spearman’s ρ ranks: eight bytes each, so 512 MiB beside the rows
read. A sample’s 100,000 rows rank up to 671 columns; a read of every row of a
large table can be past it, and the matrix then has Pearson’s r only.
Collect a LazyFrame, with the streaming engine when the streaming feature is on and
use_streaming asks. Returns PolarsError for callers that store or show it
(e.g. DataTableState::error).
Describe statistics for a frame. With sample_size, a table with more rows than
that is described from a sample (see crate::analysis::sampling::analysis_rows); without it, every row is
aggregated in one streaming pass, never held. known_total saves a count.
Computes describe statistics in a single aggregation pass over the DataFrame.
Uses one collect() with aggregated expressions for all columns (count, null_count, mean, std, min, percentiles, max).
Statistics for a LazyFrame, over the rows a crate::analysis::sampling::Sample picks from
lf, which is already cut to the sample’s scope. Describe for every column;
numeric percentiles, skewness, kurtosis, distribution fits and the correlation
matrix as options asks.
Whether a query over lf may use the streaming engine: asked for, and possible.
Polars 0.55’s streaming engine cannot run an anonymous scan (a SQLite table): it
stops at a todo!.