function table_merge ( input_file_name, tolerance )

%*****************************************************************************80
%
%% MAIN is the main program for TABLE_MERGE.
%
%  Discussion:
%
%    TABLE_MERGE merges points in a dataset.
%
%    The dataset is presumed to be an M by N array of real numbers,
%    where M is the spatial dimension, and N is the number of sample points.
%
%    The dataset is presumed to be stored in a file, with N records,
%    one per each sample point.  (Comment records may be included,
%    which begin with '#'.)
%
%    The program reads the data file and a tolerance, merges those
%    points that are closer than some tolerance, and writes out
%    a file of the merged points.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    18 March 2008
%
%  Author:
%
%    John Burkardt
%
%  Usage:
%
%    table_merge ( 'input_file_name', tolerance )
%
  timestamp ( );

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TABLE_MERGE\n' );
  fprintf ( 1, '  MATLAB version\n' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read a dataset of N points in M dimensions,\n' );
  fprintf ( 1, '  and a tolerance TOL,\n' );
  fprintf ( 1, '  write the modified dataset to a file.\n' );
%
%  If at least one command line argument, it's the input file name.
%
  if ( 1 <= nargin )

  else

    fprintf ( 1, '\n' );
    fprintf ( 1, 'TABLE_MERGE:\n' );

    input_file_name = input ( '  Enter the name of the input file.' );

  end
%
%  If at least two command line arguments, the second one is the tolerance.
%
  if ( 2 <= nargin )

  else

    fprintf ( 1, '\n' );
    fprintf ( 1, 'TABLE_MERGE:\n' );

    tolerance = input ( '  Enter the tolerance.' );

  end
%
%  Create the output file name from the input file name.
%
  output_file_name = file_name_ext_swap ( input_file_name, 'merge.txt' );

  [ m, input_n ] = r8mat_header_read (  input_file_name );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the header of "%s".\n', input_file_name );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Spatial dimension M = %d\n', m );
  fprintf ( 1, '  Number of points N  = %d\n', input_n );

  input_table = r8mat_data_read ( input_file_name, m, input_n );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the data in "%s".\n', input_file_name ) ;

  r8mat_transpose_print_some ( m, input_n, input_table, 1, 1, 5, 5, ...
    '  5 by 5 portion of data read from file:' );

  [ output_table, output_n ] = node_cluster_epsilon ( m, input_n, input_table, tolerance );
%
%  Display the output values.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Number of input points      = %d\n', input_n );
  fprintf ( 1, '  Number of output points     = %d\n', output_n );
  fprintf ( 1, '  Number of eliminated points = %d\n', input_n - output_n );

  r8mat_transpose_print_some ( m, output_n, output_table, 1, 1, 5, 5, ...
    '  5 by 5 portion of merged data:' );
%
%  Write the output values to a file.
%
  r8mat_write ( output_file_name, m, output_n, input_table );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Wrote the merged data to "%s".\n', output_file_name );

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TABLE_MERGE\n' );
  fprintf ( 1, '  Normal end of execution.\n' );

  fprintf ( 1, '\n' );
  timestamp ( );

  return
end
function column_num = file_column_count ( input_file_name )

%*****************************************************************************80
%
%% FILE_COLUMN_COUNT counts the columns in the first line of a file.
%
%  Discussion:
%
%    The file is assumed to be a simple text file.
%
%    Most lines of the file are presumed to consist of COLUMN_NUM words,
%    separated by spaces.  There may also be some blank lines, and some 
%    comment lines, which have a "#" in column 1.
%
%    The routine tries to find the first non-comment non-blank line and
%    counts the number of words in that line.
%
%    If all lines are blanks or comments, it goes back and tries to analyze
%    a comment line.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    21 February 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILE_NAME, the name of the file.
%
%    Output, integer COLUMN_NUM, the number of columns in the file.
%
  FALSE = 0;
  TRUE = 1;
%
%  Open the file.
%
  input_unit = fopen ( input_file_name );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_COLUMN_COUNT - Error!\n' );
    fprintf ( 1, '  Could not open the file "%s".\n', input_file_name );
    error ( 'FILE_COLUMN_COUNT - Error!' );
    column_num = -1;
    return;
  end
%
%  Read one line, but skip blank lines and comment lines.
%  Use FGETL so we drop the newline character!
%
  got_one = FALSE;

  while ( 1 )

    line = fgetl ( input_unit );

    if ( line == -1 )
      break;
    end

    if ( s_len_trim ( line ) == 0 )

    elseif ( line(1) == '#' )

    else
      got_one = TRUE;
      break;
    end

  end

  fclose ( input_unit );

  if ( got_one == FALSE ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_COLUMN_COUNT - Warning!\n' );
    fprintf ( 1, '  The file does not seem to contain any data.\n' );
    column_num = -1;
    return;
  end

  column_num = s_word_count ( line );

  return
end
function file_name_new = file_name_ext_swap ( file_name, ext )

%*****************************************************************************80
%
%% FILE_NAME_EXT_SWAP replaces the current "extension" of a file name.
%
%  Discussion:
%
%    The "extension" of a filename is the string of characters
%    that appears after the LAST period in the name.  A file
%    with no period, or with a period as the last character
%    in the name, has a "null" extension.
%
%  Example:
%
%          Input           Output
%    ================     =============
%    FILE_NAME    EXT     FILE_NAME_NEW
%    
%    bob.for      obj     bob.obj
%    bob.bob.bob  txt     bob.bob.txt
%    bob          yak     bob.yak
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    15 August 2005
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, character FILE_NAME(*), a file name.
%    On output, the extension of the file has been changed.
%
%    Input, character EXT(*), the extension to be used on the output
%    copy of FILE_NAME, replacing the current extension if any.
%
%    Output, character FILE_NAME_NEW(*), a copy of the input file name,
%    with the new extension.
%
  file_name_len = length ( file_name );

  ext_len = length ( ext );

  period = file_name_len + 1;

  for i = file_name_len : -1 : 1
    if ( file_name(i:i) == '.' )
      period = i;
      break
    end
  end

  file_name_new(1:period-1) = file_name(1:period-1);
  file_name_new(period) = '.';
  file_name_new(period+1:period+ext_len) = ext(1:ext_len);

  return
end
function row_num = file_row_count ( input_file_name )

%*****************************************************************************80
%
%% FILE_ROW_COUNT counts the number of row records in a file.
%
%  Discussion:
%
%    Each input line is a "RECORD".
%
%    The records are divided into three groups:
%    
%    * BLANK LINES (nothing but blanks)
%    * COMMENT LINES (begin with a '#')
%    * DATA RECORDS (anything else)
%
%    The value returned by the function is the number of data records.
%
%    By the way, if the MATLAB routine FGETS is used, instead of
%    FGETL, then the variable LINE will include line termination 
%    characters, which means that a blank line would not actually
%    have zero characters.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    31 December 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILE_NAME, the name of the input file.
%
%    Output, integer ROW_NUM, the number of rows found. 
%
  input_unit = fopen ( input_file_name );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_ROW_COUNT - Error!\n' );
    fprintf ( 1, '  Could not open the file "%s".\n', input_file_name );
    error ( 'FILE_ROW_COUNT - Error!' );
    row_num = -1;
    return;
  end

  blank_num = 0;
  comment_num = 0;
  row_num = 0;
  
  record_num = 0;

  while ( 1 )

    line = fgetl ( input_unit );

    if ( line == -1 )
      break;
    end

    record_num = record_num + 1;
    record_length = s_len_trim ( line );
    
    if ( record_length <= 0 )
      blank_num = blank_num + 1;
    elseif ( line(1) == '#' )
      comment_num = comment_num + 1;
    else
      row_num = row_num + 1;
    end

  end

  fclose ( input_unit );

  return
end
function [ node_coord, cluster_num ] = node_cluster_epsilon ( dim_num, ...
  node_num, node_coord, tolerance )

%*****************************************************************************80
%
%% NODE_CLUSTER_EPSILON clusters points with a tolerance.
%
%  Discussion:
%
%    Initially, each point is in its own cluster.  If two clusters
%    are separated by a distance of less than the tolerance, then
%    they are replaced by one cluster, whose representative point
%    is the weighted sum of the two cluster representatives.
%
%    The clusters are repeatedly processed until all clusters are
%    separated by a distance of at least the tolerance.
%
%    This algorithm may be useful when a dataset containing a number
%    of points is given, and
%
%    1) duplicate points must be removed (in this case, a value of
%       TOLERANCE = 0 will work)
%    OR
%    2) points that are very close to each other should be discarded.
%       In this case, a "small" value of TOLERANCE is appropriate.
%
%    Note that this procedure depends on the ordering of the points.
%    If you have three points A < B < C separated by slightly
%    less than the tolerance, then A and B will be merged or B and C
%    will be merged, depending on the labels of the nodes.  Thus
%    this process is not a strictly geometric procedure.
%
%    Secondly, it should be obvious that the procedure may return
%    points that were not input points, because of the use of centroids.
%
%    Third, this procedure does guarantee that the output points are
%    separated by more than TOLERANCE units of distance.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    18 March 2008
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer DIM_NUM, the spatial dimension.
%
%    Input, integer NODE_NUM, the number of nodes.
%
%    Input, real NODE_COORD(DIM_NUM,NODE_NUM), the node coordinates.
%
%    Input, real ( kind = 8 ) TOLERANCE, the distance tolerance.
%
%    Output, real NODE_COORD(DIM_NUM,NODE_NUM), the coordinates of 
%    the cluster representatives.
%
%    Output, integer CLUSTER_NUM, the number of clusters.
%
  weight(1:node_num) = 1.0;

  while ( 1 )

    found = 0;

    for cluster1 = 1 : node_num

      if ( weight(cluster1) == 0.0 )
        continue
      end

      for cluster2 = 1 : cluster1 - 1

        if ( weight(cluster2) == 0.0 )
          continue
        end

        dist = norm ( node_coord(1:dim_num,cluster1) - node_coord(1:dim_num,cluster2) );

        if ( dist <= tolerance )

          found = 1;

          node_coord(1:dim_num,cluster2) = ...
            ( weight(cluster1)                    * node_coord(1:dim_num,cluster1) ...
                               + weight(cluster2) * node_coord(1:dim_num,cluster2) ) / ...
            ( weight(cluster1) + weight(cluster2) );

          weight(cluster2) = weight(cluster1) + weight(cluster2);

          weight(cluster1) = 0.0;

        end

      end

    end

    if ( ~found )
      break
    end

  end

  cluster_num = 0;

  for node = 1 : node_num

    if ( 0.0 < weight(node) )
      cluster_num = cluster_num + 1;
      node_coord(1:dim_num,cluster_num) = node_coord(1:dim_num,node);
    end

  end

  return
end
function table = r8mat_data_read ( input_filename, m, n )

%*****************************************************************************80
%
%% R8MAT_DATA_READ reads data from an R8MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    27 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Input, integer M, N, the number of rows and columns of data.
%
%    Output, real TABLE(M,N), the point coordinates.
%
  table = [];
%
%  Build up the format string for reading M real numbers.
%
  string = ' ';

  for i = 0 : m
    string = strcat ( string, ' %f' );
  end

  input_unit = fopen ( input_filename );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_DATA_READ - Error!\n' );
    fprintf ( 1, '  Could not open the file.\n' );
    error ( 'R8MAT_DATA_READ - Error!' );
    return;
  end

  i = 0;

  while ( i < n )

    line = fgets ( input_unit );

    if ( line == -1 )
      break;
    end

    if ( line(1) == '#' )

    elseif ( s_len_trim ( line ) == 0 )
      
    else

      [ x, count ] = sscanf ( line, string );

      if ( count == m )
        i = i + 1;
        table(1:m,i) = x(1:m);
      end

    end

  end

  fclose ( input_unit );

  return
end
function [ m, n ] = r8mat_header_read ( input_filename )

%*****************************************************************************80
%
%% R8MAT_HEADER_READ reads the header from an R8MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    22 October 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Output, integer M, the spatial dimension.
%
%    Output, integer N, the number of points.
%
  m = file_column_count ( input_filename );

  if ( m <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data columns in\n' );
    fprintf ( 1, '  the file %s.\n', input_filename );
  end

  n = file_row_count ( input_filename );

  if ( n <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data rows in\n' );
    fprintf ( 1, '  the file %s\n', input_filename );
  end

  return
end
function r8mat_transpose_print ( m, n, a, title )

%*****************************************************************************80
%
%% R8MAT_TRANSPOSE_PRINT prints an R8MAT, transposed.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    10 August 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer M, N, the number of rows and columns.
%
%    Input, real A(M,N), an M by N matrix to be printed.
%
%    Input, string TITLE, an optional title.
%
  r8mat_transpose_print_some ( m, n, a, 1, 1, m, n, title );

  return
end
function r8mat_transpose_print_some ( m, n, a, ilo, jlo, ihi, jhi, title )

%*****************************************************************************80
%
%% R8MAT_TRANSPOSE_PRINT_SOME prints some of an R8MAT, transposed.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    23 May 2005
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer M, N, the number of rows and columns.
%
%    Input, real A(M,N), an M by N matrix to be printed.
%
%    Input, integer ILO, JLO, the first row and column to print.
%
%    Input, integer IHI, JHI, the last row and column to print.
%
%    Input, string TITLE, an optional title.
%
  incx = 5;

  if ( 0 < s_len_trim ( title ) )
    fprintf ( 1, '\n' );
    fprintf ( 1, '%s\n', title );
  end

  for i2lo = max ( ilo, 1 ) : incx : min ( ihi, m )

    i2hi = i2lo + incx - 1;
    i2hi = min ( i2hi, m );
    i2hi = min ( i2hi, ihi );

    inc = i2hi + 1 - i2lo;
    
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Row: ' );
    for i = i2lo : i2hi
      fprintf ( 1, '%7d       ', i );
    end
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Col\n' );

    j2lo = max ( jlo, 1 );
    j2hi = min ( jhi, n );

    for j = j2lo : j2hi

      fprintf ( 1, '%5d ', j );
      for i2 = 1 : inc
        i = i2lo - 1 + i2;
        fprintf ( 1, '%12f', a(i,j) );
      end
      fprintf ( 1, '\n' );

    end

  end

  return
end
function r8mat_write ( output_filename, m, n, table )

%*****************************************************************************80
%
%% R8MAT_WRITE writes an R8MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    11 August 2009
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string OUTPUT_FILENAME, the output filename.
%
%    Input, integer M, the spatial dimension.
%
%    Input, integer N, the number of points.
%
%    Input, real TABLE(M,N), the points.
%

%
%  Open the file.
%
  output_unit = fopen ( output_filename, 'wt' );

  if ( output_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_WRITE - Error!\n' );
    fprintf ( 1, '  Could not open the output file.\n' );
    error ( 'R8MAT_WRITE - Error!' );
    return;
  end
%
%  Write the data.
%
%  For smaller data files, and less precision, try:
%
%     fprintf ( output_unit, '  %14.6f', table(i,j) );
%
  for j = 1 : n
    for i = 1 : m
      fprintf ( output_unit, '  %24.16f', table(i,j) );
    end
    fprintf ( output_unit, '\n' );
  end
%
%  Close the file.
%
  fclose ( output_unit );

  return
end
function len = s_len_trim ( s )

%*****************************************************************************80
%
%% S_LEN_TRIM returns the length of a character string to the last nonblank.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    14 June 2003
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string S, the string to be measured.
%
%    Output, integer LEN, the length of the string up to the last nonblank.
%
  len = length ( s );

  while ( 0 < len )
    if ( s(len) ~= ' ' )
      return
    end
    len = len - 1;
  end

  return
end
function word_num = s_word_count ( s )

%*****************************************************************************80
%
%% S_WORD_COUNT counts the number of "words" in a string.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    30 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string S, the string to be examined.
%
%    Output, integer WORD_NUM, the number of "words" in the string.
%    Words are presumed to be separated by one or more blanks.
%
  FALSE = 0;
  TRUE = 1;

  word_num = 0;
  s_length = length ( s );

  if ( s_length <= 0 )
    return;
  end

  blank = TRUE;

  for i = 1 : s_length

    if ( s(i) == ' ' )
      blank = TRUE;
    elseif ( blank == TRUE )
      word_num = word_num + 1;
      blank = FALSE;
    end

  end

  return
end
function timestamp ( )

%*****************************************************************************80
%
%% TIMESTAMP prints the current YMDHMS date as a timestamp.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    14 February 2003
%
%  Author:
%
%    John Burkardt
%
  t = now;
  c = datevec ( t );
  s = datestr ( c, 0 );
  fprintf ( 1, '%s\n', s );

  return
end