(maxima.info)Functions and Variables for plain-text input and output

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74.2 Functions and Variables for plain-text input and output
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 -- Function: read_matrix
          read_matrix (<S>)
          read_matrix (<S>, <M>)
          read_matrix (<S>, <separator_flag>)
          read_matrix (<S>, <M>, <separator_flag>)

     'read_matrix(<S>)' reads the source <S> and returns its entire
     content as a matrix.  The size of the matrix is inferred from the
     input data; each line of the file becomes one row of the matrix.
     If some lines have different lengths, 'read_matrix' complains.

     'read_matrix(<S>, <M>)' read the source <S> into the matrix <M>,
     until <M> is full or the source is exhausted.  Input data are read
     into the matrix in row-major order; the input need not have the
     same number of rows and columns as <M>.

     The source <S> may be a file name or a stream which for example
     allows skipping the very first line of a file (that may be useful,
     if you read CSV data, where the first line often contains the
     description of the columns):
          s : openr("data.txt");
          readline(s);  /* skip the first line */
          M : read_matrix(s, 'comma);  /* read the following (comma-separated) lines into matrix M */
          close(s);

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', and 'space'.  If <separator_flag> is not specified,
     the file is assumed space-delimited.

 -- Function: read_array
          read_array (<S>, <A>)
          read_array (<S>, <A>, <separator_flag>)

     Reads the source <S> into the array <A>, until <A> is full or the
     source is exhausted.  Input data are read into the array in
     row-major order; the input need not conform to the dimensions of
     <A>.

     The source <S> may be a file name or a stream.

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', and 'space'.  If <separator_flag> is not specified,
     the file is assumed space-delimited.

 -- Function: read_hash_table
          read_hash_table (<S>, <A>)
          read_hash_table (<S>, <A>, <separator_flag>)

     Reads the source <S> and returns its entire content as a 'hashed
     array'.  The source <S> may be a file name or a stream.

     'read_hash_table' treats the first item on each line as a hash key,
     and associates the remainder of the line (as a list) with the key.
     For example, the line '567 12 17 32 55' is equivalent to 'A[567]:
     [12, 17, 32, 55]$'.  Lines need not have the same numbers of
     elements.

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', and 'space'.  If <separator_flag> is not specified,
     the file is assumed space-delimited.

 -- Function: read_nested_list
          read_nested_list (<S>)
          read_nested_list (<S>, <separator_flag>)

     Reads the source <S> and returns its entire content as a nested
     list.  The source <S> may be a file name or a stream.

     'read_nested_list' returns a list which has a sublist for each line
     of input.  Lines need not have the same numbers of elements.  Empty
     lines are not ignored: an empty line yields an empty sublist.

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', and 'space'.  If <separator_flag> is not specified,
     the file is assumed space-delimited.

 -- Function: read_list
          read_list (<S>)
          read_list (<S>, <L>)
          read_list (<S>, <separator_flag>)
          read_list (<S>, <L>, <separator_flag>)

     'read_list(<S>)' reads the source <S> and returns its entire
     content as a flat list.

     'read_list(<S>, <L>)' reads the source <S> into the list <L>, until
     <L> is full or the source is exhausted.

     The source <S> may be a file name or a stream.

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', and 'space'.  If <separator_flag> is not specified,
     the file is assumed space-delimited.

 -- Function: write_data
          write_data (<X>, <D>)
          write_data (<X>, <D>, <separator_flag>)

     Writes the object <X> to the destination <D>.

     'write_data' writes a matrix in row-major order, with one line per
     row.

     'write_data' writes an array created by 'array' or 'make_array' in
     row-major order, with a new line at the end of every slab.
     Higher-dimensional slabs are separated by additional new lines.

     'write_data' writes a hashed array with each key followed by its
     associated list on one line.

     'write_data' writes a nested list with each sublist on one line.

     'write_data' writes a flat list all on one line.

     The destination <D> may be a file name or a stream.  When the
     destination is a file name, the global variable
     'file_output_append' governs whether the output file is appended or
     truncated.  When the destination is a stream, no special action is
     taken by 'write_data' after all the data are written; in
     particular, the stream remains open.

     The recognized values of <separator_flag> are 'comma', 'pipe',
     'semicolon', 'space', and 'tab'.  If <separator_flag> is not
     specified, the file is assumed space-delimited.