r_data.pl -- R data frame handling

This library provides predicates for creating and fetching R data frames. R data frames are typically 2-dimensional arrays where the data is organised in columns. In Prolog, data is typically organised in rows (or records).

 r_data_frame(+Rvar, +Columns, :Goal) is det

Create an R data.frame from the solutions of Goal. The resulting data frame is bound to the R variable Rvar. For example:

?- r_data_frame(movieyear,
                [movie=Name, year=Year],
                movie(Name, Year)).

Arguments:

Rvar	- is the name of the R output variable
Columns	- is a list Name=Var

 r_data_frame_to_dicts(+DataFrame, -Dicts) is det

Translate a DataFrame into a list of dicts, where each dict represents a row. The keys of the dicts are fetched from colnames(DataFrame). For example:

?- r_data_frame_to_dicts(mtcars, Dicts).
Dicts = [ row{am:1, carb:4, cyl:6, disp:160.0, drat:3.9,
              gear:4, hp:110, mpg:21.0, qsec:16.46, vs:0,
              wt:2.62},
          ...
        ]

 r_data_frame_to_rows(+DataFrame, +Functor, -Rows) is det

Translate a 2-dimensional R dataframe into a list of compound terms, each representing a row. The functor of each row is Functor. For example:

?- r_data_frame_to_rows(mtcars, car, Rows).
Rows = [ car(21.0, 6, 160.0, 110, 3.9, 2.62, 16.46, 0, 1, 4, 4),
         ...
       ].

 r_data_frame_from_dicts(+DataFrame, +Rows) is det

Assign the R variable DataFrame the content of Rows. Rows is a list of dicts that must all have the same set of keys. The keys are used as column names.

See also

- dicts_to_same_keys/3 to align the set of keys for each dict

 r_data_frame_from_rows(+DataFrame, +Rows) is det

Assign the R variable DataFrame the content of Rows. Rows is a list of compound terms.

 r_data_frame_colnames(+DataFrame, -ColNames:list(atom)) is det

ColNames are the column names for DataFrame as a list of atoms.

 r_data_frame_rownames(+DataFrame, -RowNames:list(atom)) is det

RowNames are the row names for DataFrame as a list of atoms.