ARFFFiles.jl

Load and save ARFF (Attribute Relation File Format) files.

Integrated into Tables.jl for easily converting to your favourite table types.

Install

] add ARFFFiles

Quick start

To load an ARFF file as a DataFrame:

using ARFFFiles, DataFrames
df = ARFFFiles.load(DataFrame, "mytable.arff")

Replace DataFrame with your favourite table type, or leave it out to get an ARFFTable.

To save any Tables.jl-compatible table:

using ARFFFiles
ARFFFiles.save("mytable.arff", df)

Loading

load(file) loads the table in the given file (filename or IO stream) as an ARFFTable.
load(func, file) is equivalent to func(load(file)) but operates recursively on any relational columns.
loadstreaming(file) returns a ARFFReader object r:
- Satisfies the Tables.jl interface, so can be materialized as a table.
- r.header contains the header parsed from io.
- Iterates rows of type ARFFRow.
- read(r), read(r, n) and read!(r, x) reads rows of the table.
- readcolumns(r, [maxbytes=nothing]) reads the whole table into a columnar format. Specify maxbytes to read a portion of the rows.
- close(r) closes the underlying io stream, unless own=false.
loadstreaming(func, file) is equivalent to func(loadstreaming(file)) but ensures the file is closed afterwards.
loadchunks(file) returns an iterator of ARFFTables for efficiently streaming very large tables. Equivalent to Tables.partitions(loadstreaming(file)).
loadchunks(func, file) is equivalent to func(loadchunks(file)) but ensures the file is closed afterwards.

Types. Numbers load as Float64, strings as String, dates as DateTime, nominals as CategoricalValue{String} (from CategoricalArrays) and relationals as ARFFTable.

Keyword options.

missingcols=:auto: Controls which columns may contain missing data (?). It can be :auto, :all, :none, a set or vector of column names (symbols), or a function taking a symbol and returning true if that column can contain missing. If the table is being read in a streaming fashion, then :auto behaves the same as :all.
missingnan=false: Convert missing values in numeric columns to NaN. This is equivalent to excluding these columns in missingcols.
categorical=true: When false, nominal columns are converted to String instead of CategoricalValue{String}.
chunkbytes=2^26: Read approximately this many bytes per chunk when iterating over chunks or rows.
own=false: Signals whether or not to close the underlying IO stream when close(::ARFFReader) is called.

Saving

save(file, table) saves the Tables.jl-compatible table to file (a filename or IO stream).

Types. Real is saved as numeric, AbstractString as string, DateTime and Date as date, and CategoricalValue{<:AbstractString} as nominal.