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READFMT

READFMT

Name


    READFMT

Purpose


      Quickly read a fixed format ASCII data file into IDL variables.

Explanation


      Lines of data not meeting the specified format (e.g. comments) are
      ignored.
     
      To read a free format ASCII data file use the procedures
      READCOL or RDFLOAT. To print (formatted or free) columns of data
      use the procedure FORPRINT.

Calling Sequence


      READFMT, name, fmt, v1,[ v2, v3, v4, ..., v25 ,
                          /SILENT, /DEBUG, SKIPLINE= , NUMLINE =]

Inputs


      NAME - Name of ASCII data file. An extension of .DAT is assumed,
              if not supplied.
      FMT - scalar string containing a valid FORTRAN read format.
              Must include a field length specification. Cannot include
              internal parenthesis. A format field must be included for
              each output vector. Multiple format fields are allowed, but
              the repetition factor must be less than 100, (.i.e. 19X is
              allowed but 117X is illegal)
      Examples of valid FMT values are
              FMT = 'A7,3X,2I4' or FMT = '1H ,5I7,2A7'
      Examples of INVALID FMT values are
              FMT = 'A7,B3' ;'B' is not a valid FORTRAN format
              FMT = 'A7,2(I3,F5.1)' ;Internal parenthesis not allowed
              FMT = 'A7,F,I' ;Field length not included

Outputs


      V1,V2,V3,V4... - IDL vectors to contain columns of data.
              Up to 25 output vectors may be read. The type of the output
              vectors are specified by FMT.

Optional Keyword Inputs


      /SILENT - If this keyword is set and non-zero, then certain terminal
              output is suppressed while reading the file
      /DEBUG - Set this keyword to display additional information while
              reading the file.
      SKIPLINE - Scalar specifying number of lines to skip at the top of
              file before reading. Default is to start at first line
      NUMLINE - Scalar specifying number of lines in the file to read.
              Default is to read the entire file

Examples


      Each row in a fixed-format file POSITION.DAT contains a 5 character
      star name and 6 columns of data giving an RA and Dec in sexagesimal
      format. A possible format for such data might be
      IDL> FMT = 'A5,2I3,F5.1,2x,3I3'
      and the file could be quickly read with
      IDL> READFMT,'POSITION', fmt, name, hr, min, sec, deg, dmin, dsec
   
      NAME will be a string vector,SEC will be a floating point vector, and
      the other vectors will be of integer type.

Restrictions


      This procedure is designed for generality and not for speed.
      If a large ASCII file is to be read repeatedly, it may be worth
      writing a specialized reader.

Notes


      When reading a field with an integer format I<n>, the output vector is
              byte - if n = 1
              integer*2 - if 1 < n < 5
              integer*4 - in all other cases
      Octal ('O') and hexadecimal ('Z') formats are read into longwords

Procedure Calls


      GETTOK(), REMCHAR, ZPARCHECK

Revision History


      Written W. Landsman November, 1988
      Added SKIPLINE and NUMLINE keywords March 92
      Allow up to 25 columns to be read June 92
      Call NUMLINES() function Feb 1996
      Recognize 'O' and 'Z' formats W. Landsman September 1997
      Recognize 'G' format, use SKIP_LUN W. Landsman May 2010



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