CHANGELOG.md

Changelog polars (Python bindings)

The Rust crate polars has its own changelog.

polars 0.7.13 / 0.7.14 (patch) 2021-05-08

• bug fix

  • fix bug in cum_sum #604

• feature

  • DataFrame.describe method #606
  • Multi-level sorting of a DataFrame #607
  • Expand functionality of Expr.is_in #614
  • Csv-parser low_memory option #615
  • Allow expressions in pl.arange #611

• performance

  • sort().reverse() optimization #605

polars 0.7.12

• bug fix
  • null handling in mean, std, var, and cov aggregations. #595
  • rev-mapping of categorical stored duplicates. #595
  • fix memory surge after csv-parsing #593

polars 0.7.11

• bug fix

  • Throw error on join from different string cache #584
  • fix covariance of array with null values #585

• feature

  • Series describe method #569
  • dsl: take, arg_unique, unique
  • allow lazy expressions in Eager API # 588
  • describe Series

• performance

  • fix accidental expensive appends #592
  • remove chunk_id from ChunkedArray #593

polars 0.7.8 -> 0.7.9 (patched)

• bug fix

  • ensure column name persist after pyarrow cast #563
  • make sure that agg_list maintains dtype #567
  • fix panic in physical dispatch of Date dtypes

• feature

  • Implicitly Cast dtypes to temporal types in csv parser #560
  • Series describe method #569

• performance

  • Cache and improve window functions performance #570

polars 0.7.7

• bug fix

  • fix bug with pyarrow chunkedarray: #545

• feature

  • DataFrame.apply method
  • Make a Series a Literal
  • Make None a Literal

• performance

  • Update arrow
    • faster iterators
    • faster kernels

polars 0.7.6

• bug fix

  • fix bug in downsample: #537

• feature

  • cast categorical in csv parser: #533
  • add many groupby-context aware operations: #534
  • dowcast by month: #537

• performance

  • improve iterator in no null case: #538
  • remove indirection: #536

polars 0.7.5

• bug fix

  • fix bug in vectorized hashing algorithm that affected groupbys with null values: #523
  • fix bug in downsample: 528
  • change median algorithm: #527

• feature

  • use lazy groupby API/DSL in eager API: #522
  • make sort groupby-context aware: #522

• performance

  • improve sort algorithms for sort and argsort: #526

polars 0.7.4

• performance

  • [python | rust] multi-threaded outer join
  • [python | rust] better performance in groupby on multiple keys (faster hashmap comparisons)
  • [python | rust] better performance in multi column joins

• bug fix

  • [python] make horizontal aggregations null aware

• feature

  • [python | rust] Downsample by week
  • [python | rust] join by unlimited columns
  • [python] Create a list Series directly.
  • [python] Create DataFrame from np.ndarray

polars 0.7.3

• bug fix

  • [python] pandas to polars date64, maintain time information
  • [python] fix bug in Date64 Series.year
  • [python] fix bug Series.mean (did not correct for null values) #484
  • [python | rust ] fix bug in rolling windows #484
  • [python | rust ] fix bug lazy csv parser #459

• feature

  • [python | rust] Series methods
    • Series.week
    • Series.weekday
    • Series.arg_min
    • Series.arg_max
    • Series.shape

polars 0.7.2

• bug fix

  • [python] More pyarrow -> polars conversions.

• feature

  • [python] DataFrame methods: [ shift_and_fill].
  • [python] eager: sum, min, max, mean horizontal aggregation.

polars 0.7.1

• performance
  • [python | rust] arrow arrays have a layer of indirection less; 10/20% performance improvement

polars 0.7.0

• name change: Python bindings module renamed from pypolars to polars

• name change: Python bindings package renamed from py-polars to polars

• feature

  • [python] lazy: DataFrame methods: [ tail, first, last ].
  • [python] eager: DataFrame fold for horizontal aggregation.
  • [python] eager: Series methods: [median, quantile, is_in, to_frame]
  • [python] eager: iterate over groupby and yield groups' DataFrames
  • [python] eager: groupby.get_group('value')
  • [python] add parquet compression
  • [python] shift_and_fill expression
  • [python] implicitly download raw files from the web in read_parquet, read_csv.
  • [python | rust] methods for local peak finding in numerical series
  • [python | rust] faster query optimization due to local memory arena's.
  • [rust] reduce default compile time by making less features default.
  • [python | rust] Series zip_with implicitly cast to supertype.
  • [python | rust] window functions have a min_periods argument to control when to compute a result

• bug fix

  • [python] support file buffers for reading and writing csv and parquet
  • [python | rust] fix csv-parser: allow new-line character in a string field
  • [python | rust] don't let predicate-pushdown pass shift | sort operation to maintain correctness.

py-polars 0.6.7

• performance
  • [python | rust] use mimalloc global allocator
  • [python | rust] undo performance regression on large number of threads
• bug fix
  • [python | rust] fix accidental over-allocation in csv-parser
  • [python] support agg (dictionary aggregation) for downsample

py-polars 0.6.6

• performance
  • [python | rust] categorical type groupby keys (use size hint)
  • [python | rust] remove indirection layer in vector hasher
  • [python | rust] improve performance of null array creation
• bug fix
  • [python] implement set_with_mask for Boolean type
  • [python | rust] don't panic (instead return null) in dataframe aggregation std and var
• other
  • [rust] internal refactors

py-polars 0.6.5

• bug fix
  • [python] fix various pyarrow related bugs

py-polars 0.6.4

• feature
  • [python] render html tables
• performance
  • [python] default to pyarrow for parquet reading
  • [python | rust] use u32 instead of usize in groupby and join to increase cache coherence and reduce memory pressure.