examples/

README

golars examples

Runnable programs that demonstrate golars usage. Each subdirectory is a main package: run with go run ./examples/<name>.

A subset of examples ship a second main under generic/. That variant uses the typed expr.C[T] / expr.Int / expr.Float / expr.Str / expr.Bool facade introduced in expr/typed.go to eliminate expr.Lit(int64(X)) boilerplate. The logical plan is identical; only the caller syntax differs. Run with go run ./examples/<name>/generic.

Core API

Directory	What it shows
basic	Build a DataFrame from slices; basic operations (head, filter, sort).
describe	Summary statistics via DataFrame.Describe(ctx).
expressions	Column expressions (Col, literal, arithmetic) and select/with_columns.
groupby	GroupBy with sum/mean/count aggregations.
join	Inner and left joins across two DataFrames.
lazy	The LazyFrame pipeline (filter → groupby → sort) with collect.
streaming	Streaming execution over large inputs via the morsel engine.

Reshape / aggregation

Directory	What it shows
horizontal	SumHorizontal, MeanHorizontal, SumAll - row-wise + frame-scalar aggregates.
pivot	df.Pivot(index, on, values, PivotSum) - long-to-wide reshape.
transpose_unpivot	df.Transpose, df.Unpivot (melt).
topk_pipe	df.TopK / df.BottomK, df.Pipe method-chaining helper.
over_window	Expr.Over(keys...) - window functions broadcast back to rows.
rolling	Expr.RollingMean/Std/Min/Max(window, minPeriods) on a price series.

Control flow / expressions

Directory	What it shows
when_then	When(pred).Then(a).Otherwise(b) with dtype promotion.
coalesce_concat	Coalesce, ConcatStr, IntRange - polars-style constructors.
fill_strategies	ForwardFill, BackwardFill, FillNan on a nullable time series.
stats	Skew, Kurtosis, PearsonCorr, Covariance, ApproxNUnique, df.Corr.
regex_strings	Str().Extract, ContainsRegex, SplitExactNullShort.

I/O

Directory	What it shows
csv	Read and write CSV files.
csv_url	Fetch a CSV from an http(s) URL.
parquet	Read and write Parquet files.
json	Array-of-objects JSON read/write.
ndjson	Newline-delimited JSON read/write.
arrow_interop	DataFrame ↔ arrow.RecordBatch / arrow.Table round trip.
ipc_streaming	Arrow IPC stream: write multiple batches, read them back.
scan_pushdown	iocsv.Scan() with predicate + projection pushdown through to the reader.

Querying + tooling

Directory	What it shows
sql	Nested module. Read a query result into a DataFrame via modernc.org/sqlite (pure-Go). Run with cd examples/sql && go run ..
sql_session	sql.Session Register + Query to run SQL directly against in-memory DataFrames.
script	.glr script samples (agg, branching, derived, join, multisource, nulls, pipeline, regex, rolling) plus a host program driving script.Runner. script/transpiled/ has the same scripts lowered to Go via golars transpile.
profiler	lazy.NewProfiler() + lazy.WithProfiler(p) for per-node timings.

Notes

Most examples create in-memory DataFrames so no external files are needed. The csv_url example hits httpbin.org; set GOLARS_EXAMPLE_URL to point at a different endpoint if that host is unreachable. scan_pushdown seeds a tiny CSV in $TMPDIR.