error on string <-> date cmp (#6498)
Formalize list aggregation difference between groupbys, selection and window functions (#6487)
show where error messages originated (#6482)
str.strip with multiple chars (#5929)

🚀 Performance improvements

update string replacement codepaths following new benchmarking (#6777)
improve dynamic groupby performance on sorted keys (#6599)
faster frame-init from list of dicts (when omitting fields), and ensure fields are read according to the declared schema (#6472)
Improve rechunk check (#6268)
reuse allocated scratches in ipc writer (#6287)
use dedicated writer thread for sink_parquet (#6285)
first check rev-map on categorical equality check (#6085)
ensure set_at_idx is O(1) (#5977)
use iterator instead of loop polars_io::csv::parser::skip_condition (#5157)

✨ Enhancements

accept separator for pivot and to_dummies (#6780)
feat(rust, python) rename 'tz' to 'time_zone' in convert_time_zone and replace_time_zone (#6784)
rename with_time_zone to convert_time_zone and cast_time_zone to replace_time_zone (#6768)
support timezone in csv writer (#6722)
implement series abstractions for Int128Type (#6679)
parse timezone from Datetime (#6766)
formally support duration division (#6758)
add argmin/max for utf8 data (#6746)
Support an ignore_nulls param for EWM calculations. (#5749) (#6742)
deprecate tz_localize (#6693)
guarantee schema-stable col(dtype) selection (#6674)
better-characterise NotFound exceptions (#6670)
disallow with_time_zone from/to tz-naive (#6659)
let cast_time_zone work on tz-naive and deprecate tz-localize (#6649)
implement fill_null for list data (#6635)
expression functions should be nullable (#6629)
add streamable udfs (#6614)
is_first for struct dtype (#6595)
Added from_str_radix method to StringNameSpace that allows to parse strings from any base to i32 (#6570)
improve predicate pushdown (#6579)
raise error on invalid binary cmp (#6564)
let cast_time_zone accept None (#6539)
add utc parameter to strptime (#6496)
add meta 'has_multiple_outputs', 'is_regex_projec… (#6500)
error on string <-> date cmp (#6498)
show where error messages originated (#6482)
faster frame-init from list of dicts (when omitting fields), and ensure fields are read according to the declared schema (#6472)
allow expr in str.contains (#6443)
add float formatting option (#6432)
allow expressions as arguments in str.ends_with (#6361)
accept expr in str.starts_with (#6355)
add strict parameter to decoding expressions (#6342)
allow unordered struct creating from anyvalues (#6321)
parse abbrev month name (#6314)
add dt.combine for combining date and time components (#6121)
add sink_ipc (#6286)
ensure ooc sort works ooc with all-constant values (#6235)
The 1 billion row sort (#6156)
optionally treat missing UTF8 values as the empty string at CSV parse-time (#6203)
When moving error out of LogicalPlan, leave behind String with error message instead of None (#6199)
generalize the cloud storage builders (#5972)
Implement DataFrame.unique(keep="none") (#6169)
add arr.take expression (#6116)
allow extend_constant to work with date literals (#6114)
allow nested categorical cast (#6113)
add a rounded_corners modifier to pl.Config.set_tbl_formatting (#6108)
Get polars to compile to wasm target (#6050)
add search_sorted for arrays and utf8 dtype (#6083)
improve error message when writing nested data to… (#6040)
updated default table format from "UTF8_FULL" to "UTF8_FULL_CONDENSED" (#5967)
str.strip with multiple chars (#5929)
support glob in parquet object_storage (#5928)
read decimal as f64 (#5938)
improve query plan scan formatting (#5937)
allow all null cast (#5933)
truncate by calendar weeks (#5759)
merge sorted dataframes (#5817)
impl hex and base64 for binary (#5892)
streaming parquet from object_stores (#5871)

🐞 Bug fixes

always rechunk if n_chunks > n_rows (#6786)
fix ndjson empty array parsing (#6785)
make some list expressions aware of groupby context (#6776)
use explicit drop function node (#6769)
don't set sorted flag if we reverse sort the left … (#6772)
handle edge-case with string-literal replacement when the replace value looks like a capture group (#6765)
respect skip_rows in glob parsing csv (#6754)
Improve error message in DataFrame constructor (#6715)
arrow map dtype conversion (#6732)
dedicated rename implementation. (#6688)
return correct display/repr names for NaN-related expressions (#6721)
strftime with time zone directive (#6673)
improve error message in date_range with invalid units (#6671)
remove uses of rayon global thread pool (#6682)
true-divide output type (#6665)
fix(rust, python) cast to and from fixed offsets (#6602)
raise error on string numeric arithmetic (#6601)
partially assert sortedness in groupby dynamic (#6593)
fix(rust, python); raise oob if negative index given to take (#6590)
fix predicate pushdown key check (#6577)
fix schema of apply with many inputs on empty df (#6571)
let lhs determine struct order in supertype (#6572)
fix(rust, python) validate utc, fmt, and tz-aware in strptime (#6550)
add strptime to filter boundary (#6560)
list eval all null array (#6545)
implement ser/de for BinaryChunked (#6543)
raise if tz_localize called on UTC-aware (#6526)
make concat_list group aware (#6527)
error on invalid expanding expression (#6521)
create from dicts directly as struct categorical (#6520)
fix oob in arr.get by expressions (#6519)
fix cse schema (#6518)
panic when max_len -1 is reached (#6494)
Formalize list aggregation difference between groupbys, selection and window functions (#6487)
fix(rust, python) validate tz in with_time_zone (#6417)
faster frame-init from list of dicts (when omitting fields), and ensure fields are read according to the declared schema (#6472)
use consistent floor division for floats/ints (#6460)
split semi/anti join optimization (#6459)
fix doc comment in ParallelStrategy (#6444)
fix projection pushdown on double semi join (#6440)
cumulative_eval ensure output dtype is respected (#6435)
auto-detect %+ as tz-aware (#6434)
correct error message in cast_time_zone (#6411)
only use float simd on specific alignment (#6427)
no early escape when window is equal to len in rolling_float (#6408)
raise error on invalid sort_by argument (#6382)
take offset into account with str.explode (#6384)
Return empty batch for pl.read_csv_batched().next_… (#6381)
implement ser/de for StructChunked (#6359)
series of empty structs (#6347)
don't cast nulls before trying normal cast (#6339)
expand all nested wildcards in functions (#6334)
fix groupby rolling by_key if groups are empty (#6333)
parse abbrev month name (#6314)
disallow alias in inline join expressions (#6312)
feature flag "get_sink" ipc (#6306)
block proj-pd and pred-pd on swapping rename (#6303)
convert nested dictionary with i64 keys (#6299)
fix panic dynamic_groupby on empty dataframe (#6294)
Parse negative dates with polars parser (#6256)
Add list inner dtype when printing Series (#6233)
fix when then otherwise with arity and aggregation… (#6224)
pass name to value counts in aggregation (#6221)
don't set fast_explode on list of structs (#6220)
explode of empty nullable list (#6190)
fix empty streaming joins (#6149)
fix streaming joins where the join order has been … (#6143)
write tz-aware datetimes to csv (#6135)
Print error message on mmap IPC file only in verbose mode (#6098)
fix invalid dtype in chunked array after struct cast (#6093)
don't run cse cache_states if no projections found (#6087)
Update read_csv error message (#6082)
propogate nulls in binary arithmetic/aggregation (#6076)
deal with unnest schema expansion in projection pd (#6063)
correct output dtype for cummin/cumsum/cummax (#6062)
block streaming on literal series/range (#6058)
ndjson struct inference (#6049)
deal with empty structs (#6039)
fix aggregation that filters out all data (#6036)
fix diff overflow (#6033)
keep column names in is_null/is_not_null (#6032)
keep name when sorting categorical in lexial order (#6029)
properly set null anyvalue if categorical is neste… (#6025)
make weekday tz-aware (#5989)
fix categorical in struct anyvalue issue (#5987)
fix invalid boolean simplification (#5976)
allow empty sort on any dtype (#5975)
properly deal with categoricals in streaming queries (#5974)
don't panic on ignored context (#5958)
don't allow named expression in arr.eval (#5957)
fix panic in join expressions (#5954)
block ordered predicates before explode (#5951)
adhere to schema in arr.eval of empty list (#5947)
fix arrow nested null conversion (#5946)
allow None in arr.slice length (#5934)
fix time to duration cast (#5932)
error on addition with datetime/time (#5931)
don't create categoricals in streaming (#5926)
object filter should keep single chunk (#5913)
csv, read escaped "" as missing (#5912)
fix pivot of signed integers (#5909)
fix latest oob in streaming convertion (#5902)
fix date + duration offsets outside of nanosecond datetime bounds (#5889)
adapt k to len in topk (#5888)

🛠️ Other improvements

propagate error in date_range with invalid time zone (#6759)
update arrow to 0.16 (#6748)
remove unreachable path in write_anyvalue (#6727)
add groupby_dynamic to docs (#6725)
chore(rust) disallow chunked datetime with_time_zone on tznaive, remove unnecessary with_time_zone (#6681)
update Required Rust version to 1.58->1.62 (#6680)
add test for raising error in apply (#6664)
Minor documentation fix (#6657)
Add release flow info to contributing guide (#6480)
address todo and use regex in tz_aware check (#6479)
Address chrono deprecation warnings (#6478)
fix doc comment in ParallelStrategy (#6444)
move binary to polars-ops (#6401)
fix a typo in csv read example (#6389)
remove roundtrip to builder (#6383)
update rustc to 2023-01-19 (#6341)
run cse optimization only if joins and caches… (#6337)
update base64 requirement from 0.13 to 0.21 (#6249)
Remove benches and criterion dependency (#6273)
update chrono-tz requirement from 0.6 to 0.8 (#6255)
Enable Dependabot (#5036)
Add missing feature attributes for csv-file (#6229)
don't set aggregated flag on null propagated aggregation. (#6191)
Revert "Use auto_doc_cfg" (#6164)
remove vertical take (#6112)
add single threaded sort internally (#6103)
mark from_chunks as unsafe (#6094)
replace exact instances of Option/Result combinators (#6088)
ensure reverse indices exist in global string cache (#5970)
refactored describe (#5922)
don't decode into utf8 (#5910)
remove unused deps (#5903)

Thank you to all our contributors for making this release possible! @2-5, @AnatolyBuga, @ChayimFriedman2, @MarceColl, @MarcoGorelli, @MatveyF, @abalkin, @alexander-beedie, @c-peters, @cannero, @chitralverma, @cojmeister, @dannyvankooten, @dependabot, @dependabot[bot], @flowlight0, @gab23r, @gam-phon, @ghuls, @gitkwr, @huitseeker, @jgmartin, @jjerphan, @johngunerli, @josh, @jvanbuel, @n8henrie, @ozgrakkurt, @papparapa, @phaile2, @plaflamme, @rben01, @ritchie46, @romanovacca, @ropoctl, @sorhawell, @stinodego, @universalmind303, @winding-lines, @yuntai and @zundertj