COLUMN - Extract a column from a file.

COLUMN may be used to extract a column of data from a text file. The file is presumed to consist of lines of data. Each line of data contains several words, separated by one or more spaces or TAB characters. The first word in each line is the first "column", and so on. COLUMN reads each line of data, pulls out the word in the requested column, and writes that word to a new file.

The program can be used in command line form:

column column_number filein fileout

or can be invoked interactively with no arguments, in which case the program will request information from the user.

For example, if file.txt contains the lines:

        CAT RED   APPLE 9.5
        MOUSE  BLUE   ORANGE 12.5
        DOG purple  Banana   34.7

then the command

column 2 file.txt mydata.txt

will copy the following data into mydata.txt:

        RED
        BLUE
        purple

Files you may copy include:

column.f90, the source code;
file.txt, a sample text file of 3 lines and 3 columns;
column1.txt, results of "column 1 file.txt column1.txt";
column2.txt, results of "column 2 file.txt column2.txt";
column3.txt, results of "column 3 file.txt column3.txt";
column4.txt, results of "column 4 file.txt column4.txt";

The list of routines includes:

COLUMN extracts a given column from a file.
GET_UNIT returns a free FORTRAN unit number.
S_TO_I reads an integer value from a string.
WORD_FIND finds the word of a given index in a string.

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Last revised on 08 September 2000.