An Introduction to DataFrames.jl

Bogumił Kamiński, February 13, 2023

The tutorial is for DataFrames.jl 1.5.0

A brief introduction to basic usage of DataFrames.

The tutorial contains a specification of the project environment version under which it should be run. In order to prepare this environment, before using the tutorial notebooks, while in the project folder run the following command in the command line:

julia -e 'using Pkg; Pkg.activate("."); Pkg.instantiate()'

Tested under Julia 1.9.0. The project dependencies are the following:

  [69666777] Arrow v2.4.3
  [6e4b80f9] BenchmarkTools v1.3.2
  [336ed68f] CSV v0.10.9
  [324d7699] CategoricalArrays v0.10.7
  [8be319e6] Chain v0.5.0
  [944b1d66] CodecZlib v0.7.1
  [a93c6f00] DataFrames v1.5.0
  [1313f7d8] DataFramesMeta v0.13.0
  [5789e2e9] FileIO v1.16.0
  [da1fdf0e] FreqTables v0.4.5
  [7073ff75] IJulia v1.24.0
  [babc3d20] JDF v0.5.1
  [9da8a3cd] JLSO v2.7.0
  [b9914132] JSONTables v1.0.3
  [86f7a689] NamedArrays v0.9.6
  [2dfb63ee] PooledArrays v1.4.2
  [f3b207a7] StatsPlots v0.15.4
  [bd369af6] Tables v1.10.0
  [a5390f91] ZipFile v0.10.1
  [9a3f8284] Random
  [10745b16] Statistics v1.9.0

I will try to keep the material up to date as the packages evolve.

This tutorial covers DataFrames.jl and CategoricalArrays.jl, as they constitute the core of DataFrames.jl along with selected file reading and writing packages.

In the last extras part mentions selected functionalities of selected useful packages that I find useful for data manipulation, currently those are: FreqTables.jl, DataFramesMeta.jl StatsPlots.jl.

TOC

Changelog:

Core functions summary

1. Constructors: DataFrame, DataFrame!, Tables.rowtable, Tables.columntable, Matrix, eachcol, eachrow, Tables.namedtupleiterator, empty, empty!
2. Getting summary: size, nrow, ncol, describe, names, eltypes, first, last, getindex, setindex!, @view, isapprox, metadata, metadata!, colmetadata, colmetadata!
3. Handling missing: missing (singleton instance of Missing), ismissing, nonmissingtype, skipmissing, replace, replace!, coalesce, allowmissing, disallowmissing, allowmissing!, completecases, dropmissing, dropmissing!, disallowmissing, disallowmissing!, passmissing
4. Loading and saving: CSV (package), CSVFiles (package), Serialization (module), CSV.read, CSV.write, save, load, serialize, deserialize, Arrow.write, Arrow.Table (from Arrow.jl package), JSONTables (package), arraytable, objecttable, jsontable, CodecZlib (module), GzipCompressorStream, GzipDecompressorStream, JDF.jl (package), JDF.save, JDF.load, JLSO.jl (package), JLSO.save, JLSO.load, ZipFile.jl (package), ZipFile.reader, ZipFile.writer, ZipFile.addfile
5. Working with columns: rename, rename!, hcat, insertcols!, categorical!, columnindex, hasproperty, select, select!, transform, transform!, combine, Not, All, Between, ByRow, AsTable
6. Working with rows: sort!, sort, issorted, append!, vcat, push!, view, filter, filter!, deleteat!, unique, nonunique, unique!, allunique, repeat, parent, parentindices, flatten, @chain (from Chain.jl package), only, subset, subset!, shuffle, prepend!, pushfirst!, insert!, keepat!
7. Working with categorical: categorical, cut, isordered, ordered!, levels, unique, levels!, droplevels!, unwrap, recode, recode!
8. Joining: innerjoin, leftjoin, leftjoin!, rightjoin, outerjoin, semijoin, antijoin, crossjoin
9. Reshaping: stack, unstack
10. Transforming: groupby, mapcols, parent, groupcols, valuecols, groupindices, keys (for GroupedDataFrame), combine, select, select!, transform, transform!, @chain (from Chain.jl package)
11. Extras:
    • FreqTables: freqtable, prop, Name
    • DataFramesMeta: @with, @subset, @select, @transform, @orderby, @by, @combine, @eachrow, @newcol, ^, $
    • StatsPlots: @df, plot, density, histogram,boxplot, violin