BAR_PLOT
Bar Plot Data => RGB Arrays.

BAR_PLOT is a library of FORTRAN90 routines, using double precision arithmetic, to make simple bar plots from data.

At the moment, the library contains only one "interesting" routine, BAR_DATA_TO_RGB, which assumes that the user wants to make a sort of bar plot. At a number of equally spaced X values, a set of Y values have been supplied, which are all nonnegative. Moreover, the Y values have been scaled so that the maximum sum (or height of the bar) over any X is 1 (or less).

BAR_DATA_TO_RGB sets up RGB color arrays that indicate the appearance of the corresponding bar plot (with gray used for parts of the plot over which bars do not extend). The arrays can easily be plotted by calling, for example, the routine PPMA_WRITE from the PPMA_IO graphics library.

In turn, a PPMA file can be turned into a number of other useful formats. For example, the CJPEG routine can convert such a file to JPEG files, and these can be displayed on web pages or turned into an animation using QuickTime Pro. (This is exactly the direction in which I intend to go with this software.)

Related Data and Programs:

BOX_PLOT is a MATLAB program which can color in specified entries of a checkerboard, corresponding to pairs of integer data.

HISTOGRAM_DISPLAY is a MATLAB program which can read data and display a histogram of it.

PPMA_IO is a FORTRAN90 library which reads or writes ASCII PPM files.

TABLE_HISTOGRAM is a FORTRAN90 program which reads a file of data and produces a histogram.

Source Code:

• bar_plot.f90, the source code.
• bar_plot.csh, commands to compile the source code.

Examples and Tests:

• bar_plot_prb.f90, a sample calling program.
• bar_plot_prb.csh, commands to compile and run the sample program.
• bar_plot_prb_output.txt, the output file.
• sines.ppma, a PPMA file created by the sample calling program, which used the PPMA_IO graphics library.
• sines.png, a PNG image of the data.
• sines.jpg, a JPEG image of the data.

List of Routines:

• ANGLE_TO_RGB returns a color on the perimeter of the color hexagon.
• BAR_DATA_EXAMPLE returns some sample bar data.
• BAR_DATA_TO_RGB makes RGB arrays from bar graph data.
• GET_UNIT returns a free FORTRAN unit number.
• I4_LOG_2 returns the integer part of the logarithm base 2 of |I|.
• I4_TO_ANGLE maps integers to points on a circle.
• PPM_CHECK_DATA checks pixel data.
• PPMA_WRITE writes an ASCII portable pixel map file.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.