pack(mtx) Working with data matrices

This is a stoics pack for SWI-Prolog that provides a medley of predicates that manages term representations of data matrices.

installation

Within SWI it is highly recommended that you install from within by using its package manager.
To install simply do:

 

   ?- pack_install(mtx).   % also installs pack(lib) if not present

   and then load with:

   ?- use_module(library(lib)).
   ?- lib(mtx).
   ?- mtx( data(mtcars), Mtcars ).
   Mtcars = [row(mpg, cyl, disp, hp, .... )| ... ]

Input/output

At the very least library(mtx) can be viewed as an addition/enhancement io of matrices to files via mtx/2.
The library can interrogate the data/ subdirectory of all installed packs for csv files using alias data.

?- mtx( data(mtcars), Mtcars ).
Mtcars = [row(mpg, cyl, disp, hp, .... )| ... ].

Where mtcars.csv is in some pack's data directory.

?- mtx_data( mtcars, Mtcars ).
Mtx = [row(mpg, cyl, disp, hp, ....)|...]

Where mtcars.csv is in pack(mtx) data subdirectory.

mtx/2 works both as input and output.

If the 2nd argument is ground, mtx/2 with output the 2nd argument to the file pointed by the 1st.
Else, the 1st argument is taken as the input file or matrix, and the 2nd argument is the same matrix in standard form.

?- tmp_file( mtc, TmpF ), mtx( pack('mtx/data/mtcars'), Mtc ), mtx( TmpF, Mtc ).
TmpF = '/tmp/pl_mtc_14092_0',
Mtc = [row(mpg, cyl,

The first call to mtx/2 above, inputs the test csv mtcars.csv, to Mtc (instantiated to list of rows).
The second call, outputs Mtc to the temporary file TmpF.

mtx/3 provides a couple of options on top of csv_read_file/3 and csv_write_file/3.

sep(Sep) is short for separator, that also understands comma, tab and space (see mtx_sep/2).
match(Match) is short for match_arity(Match)

?- mtx( data(mtcars), Mtcars, sep(comma) ).
Mtcars = [row(mpg, cyl, disp, hp, ....)|...]

Good places to start:

mtx/3
mtx_column/3
mtx_column_select/4
mtx_column_add/4
mtx_column_include_rows/4
mtx_column_kv/3
mtx_read_table/4
mtx_rows_partition/5
mtx_value_column_frequencies/3
mtx_columns_cross_table/5
mtx_apply/4
mtx_lists/2

materials

module documentation: mtx.html
sources: mtx
github: mtx

author

Nicos Angelopoulos
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London
last update: June 2021