#*****************************************************************************80
#
## nile_histogram plots a histogram of yearly flood levels for the Nile.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    27 February 2020
#
#  Author:
#
#    John Burkardt
#
  cat ( '\n' )
  cat ( 'nile_histogram:\n' )
  cat ( " ", version$version.string, "\n" )
  cat ( '  Make a histogram of yearly Nile flood levels.\n' )

  filename = "nile_data.txt"
  data <- read.table ( filename, header = FALSE )
  print ( data[1:5,1:2] )

  m = dim ( data )[1]
  n = dim ( data )[2]

  cat ( '\n' )
  cat ( '  ', m, ' x ', n, ' data records read from file.\n' )
#
#  For simplicity, copy column 2 and call it "height".
#
  height = data[,2]

  filename = "nile_histogram.png"
  png ( filename )

  hist ( height,
    main = 'Yearly Nile Flood Height',
    xlab = '<-- Height of Nile at Maximum Flood -->',
    ylab = '<-- Frequency -->',
    col = 'blue',
    breaks = 20 )

  grid ( 10, 10 )

  cat ( '  Graphics saved as "', filename, '"\n' )
#
#  Terminate.
#
cat ( "\n" )
cat ( "nile_histogram:\n" )
cat ( "  Normal end of execution.\n" )
  quit ( )