fortran-table

August 4, 2025 · View on GitHub

Fortran Functions for Table Manipulation

SQL-like table manipulation
All data are stored as character
No database API is used
Can handle large size table in joins (-O2, -O3)

Initialization

Minimum Initialization

call table%init ( nrows = 3, ncols = 3 )

Full Initialization

call table%init (                          &
    nrows    = 3,                          &
    ncols    = 3,                          &
    rownames = [ "row1", "row2", "row3" ], &
    colnames = [ "col1", "col2", "col3" ], &
    cell     = mydata,                     &
    key      = 'datetime',                 &
    name     = "mytable",                  &
    file     = "mytable.csv" )

Select

table1 = select( table, cols )

table1 = table%select( cols )

cols shall be column names / indices / logical vector

table1 = select( table, [ "col3", "col2" ] )

table1 = select( table, [ 3, 2 ] )

table1 = select( table, [ .false., .true., .false. ] )

Filter

table1 = filter( table, rows )

table1 = table%filter( rows )

rows shall be row names / indices / logical vector

table1 = filter( table, [ "row3", "row1" ] )

table1 = filter( table, [ 3, 2 ] )

table1 = filter( table, [ .true., .false., .true. ] )

Delete

table1 = delete( table, rows )

table1 = table%delete( rows )

rows shall be row names / indices / logical vector

table1 = delete( table, [ "row3", "row1" ] )

table1 = delete( table, [ 3, 2 ] )

table1 = delete( table, [ .true., .false., .true. ] )

Insert Column

table1 = table%insert_col( x, before, colname )

x shall be character / logical / integer / real vector for new column

before(optional) shall be character / integer for column position to insert before

colname(optional) shall be character for new column name

Joins

key in each table is used for matching

Inner Join

table3 = inner_join( table1, table2 )

table3 = table1%inner_join( table2 )

Left Join

table3 = left_join( table1, table2 )

table3 = table1%left_join( table2 )

table3 = table1 * table2

Right Join

table3 = right_join( table1, table2 )

table3 = table1%right_join( table2 )

In the following example, if a record with the same key exits in table1, then it is replaced by the corresponding record in table2. The first column is used for the key if not specified. If there is no matching key in table1, then the record of table2 is appended to table1.

table3 = insert_or_replace( table1, table2 )

table3 = table1%insert_or_replace( table2 )

table3 = table1 + table2

Append

Simple appending with no sorting of the two tables with the same columns

In the following example, table2 is appended to the end of table1.

table3 = append( table1, table2 )

table3 = table1%append( table2 )

CSV File I/O

Write CSV file:

call table%write_csv( file = "mytable.csv" )

Read CSV file:

call table%read_csv( file = "mytable.csv" )

Write Parquet file:

call table%write_parquet( file = "mytable.parquet" )

Column Converter

Table column (character) -> {character, logical, integer, real} vector

values = table%to_{character, logical, integer, real}( col )

col shall be integer or character

logical, allocatable :: logical_values(:)

logical_values = table%to_logical( col = 2 )

logical_values = table%to_logical( col = "col2" )

{character, logical, integer, real} vector -> Table column (character)

call table%from_{character, logical, integer, real}( vals, col )