tsv

The tsv library provides predicates for reading and writing TSV files and streams:

https://www.iana.org/assignments/media-types/text/tab-separated-values

The main object, tsv/1, is a parametric object allowing passing a single option for the handling of the header of the file (keep or skip). The tvs object extends the tsv/1 parametric object using the default keep option value.

Files and streams can be read into a list of rows (with each row being represented by a list of fields) or asserted using a user-defined dynamic predicate. Reading can be done by first loading the whole file (using the read_file/2-3 predicates) into memory or line by line (using the read_file_by_line/2-3 predicates). Reading line by line is usually the best option for parsing large TSV files.

Data can be saved to a TSV file or stream by providing the object and predicate for accessing the data plus the name of the destination file or the stream handle or alias.

API documentation

Open the ../../docs/library_index.html#tsv link in a web browser.

Loading

To load all entities in this library, load the loader.lgt file:

| ?- logtalk_load(tsv(loader)).

Testing

To test this library predicates, load the tester.lgt file:

| ?- logtalk_load(tsv(tester)).

Usage

A TSV file can be read as a list of rows:

| ?- tsv::read_file('test_files/data.tsv', Rows).

Rows = [['Name','Age','Address'], ['Paul',23,'1115 W Franklin'], ['Bessy the Cow',5,'Big Farm Way'], ['Zeke,45,'W Main St']]
yes

Alternatively, The TSV data can be saved using a public and dynamic object predicate (that must be previously declared). For example:

| ?- assertz(p(_,_,_)), retractall(p(_,_,_)).
yes

| ?- tsv(skip)::read_file('test_files/data.tsv', user, p/3).
yes

| ?-  p(A,B,C).

A = 'Paul', B = 23, C = '1115 W Franklin' ? ;
...

Given a predicate representing a table, the predicate data can be written to a file or stream. For example:

| ?- tsv::write_file('output.tsv', user, p/3).
yes