graphics_gnuplot_test

graphics_gnuplot_test, a FORTRAN90 code which illustrates how various kinds of data can be displayed and analyzed graphically, using the gnuplot() graphics package.

Some common plot types include:

• animation, a sequential display of images which are meant to suggest motion or evolution.
• bar, a display of values y(1:n) in which every value y(i) is represented by a bar of that height.
• bar3d, a display of values z(1:m,1:n) over a 2D grid, in which every value z(i,j) is represented by a bar of that height.
• barh, a display of values x(1:n) in which every value x(i) is represented by a horizontal bar of that length. The horizontal format can be more suitable for labeling bars when there are many of them.
• between, a line plot of a curve, and a filled plot of the area between the curve and the x-axis. Alternatively, a filled plot of the area between two curves.
• binary_tree, a connected directed graph with no circuits, in which each node has no more than 2 descendants.
• contour fill, a display of values z(x,y) in which the values of z are suggested by regions filled with color.
• contour line, a display of values z(x,y) in which the values of z are suggested by colored contour lines.
• decision_tree, a connected directed graph with no circuits, in which labeled nodes represent current states to be tested, and edges represent the choice or decision to move from one state to another.
• dendrogram, a connected directed graph with no circuits, which generally has a single root node, and illustrates the genealogy or relatedness of a set of objects.
• digraph, a "directed graph", nodes (possibly with defined locations, labels or colors), connected by directed edges (possibly with defined weights, labels, colors or linestyles).
• fill, a shape composed of polygons, each of which is filled with a particular color.
• graph, nodes (possibly with defined locations, labels or colors), connected by undirected edges (possibly with defined weights, labels, colors or linestyles).
• histogram, a display of values x in which the x range is divided into intervals, and the value y(i) represents the number of x values in the i-th interval, and a bar plot of intervals versus count is displayed.
• plot, a display of a single curve defined by a sequence of functional pairs (x,y(x)), or a function y=f(x) sampled over an interval, or a sequence of related pairs (x,y).
• plot3d, a 3D display of a single curve defined by a sequence of triples (x(i),y(i),z(i)), or a parametric function (x(t),y(t),z(t)) sampled over an interval.
• plots, several curves on a single display.
• scatter, a display of unconnected pairs (x,y), whose positions are indicated by markers.
• scatter3d, a 3D display of unconnected triples (x,y,z), whose positions are indicated by markers.
• scatters, a scatter plot involving several distinct sets of (x,y) pairs are displayed, distinguished by markers of different size, shape or color.
• subplots, a display involving two or more separate plots, shown as a single figure.
• surface, a 3D display of values z(x,y), represented as a surface.
• vector, a 2D display of vectors (u,v)(x,y), representing a gradient field, an ODE direction field, or a flow of some kind.

Licensing:

The computer code and data files described and made available on this web page are distributed under the MIT license

Languages:

graphics_gnuplot_test is available in a C/dislin() version and a C/gnuplot() version and a C++/dislin() version and a C++/gnuplot() version and a FORTRAN90/dislin() version and a FORTRAN90/gnuplot() version and a MATLAB version and an Octave version and a Python version and an R version.

Related Data and Programs:

dislin_test, FORTRAN90 codes which use dislin(), which is a scientific graphics package, by Helmut Michels.

gnuplot_test, FORTRAN90 codes which write data and command files so that gnuplot() can create plots of the results.

Reference:

1. Philipp Janert,
   Gnuplot in Action: Understanding Data with Graphs,
   Manning, 2010,
   ISBN13: 978-1-933988-39-8,
   LC: QA276.4.J37.

Source code:

• graphics_gnuplot_test.sh, runs all the tests.

album_bar lists the year, and total number of music albums (LP's, cassettes, CD's and dowloads) sold each year from 2007 to 2017. This data is plotted as a bar graph. The gnuplot() program is used.

• album_data.txt, a data file
• album_bar.c, reads the data and creates the gnuplot command file.
• album_bar.sh, runs the test.
• album_bar.txt, the output file.
• album_commands.txt, the gnuplot() command file.
• album_bar.png, the plot.

corkscrew_plot3d generates (X,Y,Z) points that lie along a 3D curve looking something like a corkscrew. The gnuplot() program is used.

• corkscrew_data.txt, the X, Y, Z coordinates.
• corkscrew_plot3d.f90, creates the data, and writes the GNUPLOT files.
• corkscrew_plot3d.sh, runs the test.
• corkscrew_plot3d.txt, the output file.
• corkscrew_commands.txt, commands to gnuplot that will create a plot.
• corkscrew_plot3d.png, a PNG image of the plot.

grid_surface records, on a 41x41 grid over [-2,2]x[-2,+2], the values z = exp(-(x^2+y^2)) * cos(0.25*x) * sin(y) * cos(2*(x^2+y^2)). The data is plotted as a surface.

• grid_surface.f90, creates the data, and writes the GNUPLOT files.
• grid_surface.sh, runs the test.
• grid_surface.txt, the output file.
• grid_surface_data.txt, a list of time, prey, and predator.
• grid_surface_commands.txt, commands to gnuplot that will create a plot.
• grid_surface.png, a PNG image of the plot.

mario_fill makes a simple image of Mario, by constructing a grid of squares filled with color. The gnuplot() program is used.

• mario_fill.f90, makes a command file for input to gnuplot.
• mario_fill.sh, runs the test.
• mario_fill.txt, the output file.
• mario_commands.txt, the gnuplot command file.
• mario_fill.png, a PNG image of the plot.

predator_plot3d models the populations of predators (foxes) and prey (rabbits) over time. A 3D plot of (time, rabbits, foxes) is created. The gnuplot() program is used.

• predator_data.txt, a list of time, prey, and predator.
• predator_plot3d.f90, creates the data, and writes the GNUPLOT files.
• predator_plot3d.sh, runs the test.
• predator_plot3d.txt, the output file.
• predator_commands.txt, commands to gnuplot that will create a plot.
• predator_plot3d.png, a PNG image of the plot.