GRAPHICS_EXAMPLES
Sample Data for Graphics Demonstrations

GRAPHICS_EXAMPLES, Octave programs which illustrate how various kinds of data can be displayed and analyzed graphically.

Some common plot types include:

• 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).
• plots, several curves on a single display.
• 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.
• scatter, a display of unconnected pairs (x,y), 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.
• scatter3d, a 3D display of unconnected triples (x,y,z), whose positions are indicated by markers.
• bar, a display of values y(1:n) in which every value y(i) is represented by a bar of that height.
• 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.
• fill, a shape composed of polygons, each of which is filled with a particular color.
• contour, a display of values z(x,y) in which the values of z are suggested by coloring, or by contour lines.
• surface, a 3D display of values z(x,y), represented as a surface.
• subplots, a display involving two or more separate plots, shown as a single figure.

Licensing:

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

Languages:

GRAPHICS_EXAMPLES programs are available in a C version and a C++ version and a dataset version and a FORTRAN90 version and a MATLAB version and an Octave version and a Python version.

Related Data and Programs:

GRAPHICS_EXAMPLES_CONVERT, examples which illustrate how various kinds of data can be processed and modified using the ImageMagick program convert() and its related tools.

GRAPHICS_EXAMPLES_DISLIN, examples which illustrate how various kinds of data can be displayed and analyzed graphically using the graphics library dislin();

GRAPHICS_EXAMPLES_GNUPLOT, examples which illustrate how various kinds of data can be displayed and analyzed graphically using the interactive executable graphics program gnuplot().

GRAPHICS_EXAMPLES_GRACE, examples which illustrate how various kinds of data can be displayed and analyzed graphically using the interactive executable graphics program grace().

GRAPHICS_EXAMPLES_PLOTLY1, examples which illustrate how various kinds of data can be displayed and analyzed graphically, using version 1 of the plotly() program from a browser.

Reference:

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

Examples and 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. Octave graphics comands are used.

• album_data.txt, a data file
• album_bar.m, reads and plots the data.
• album_bar.png, the plot.

AUTOMOBILE_SCATTER contains prices and weights of cars available in 1985. A scatter plot is to be made. Octave graphics comands are used.

• automobile_data.txt, a data file.
• automobile_scatter.m, reads the data and creates a scatter plot of curb weight versus price.
• automobile_scatter.png, the plot.

BROWNIAN_2D_PLOT plots data representing 1000 steps of Brownian motion in two dimensions. Unlike a typical y=f(x) plot, this data wanders around the page. Octave graphics comands are used.

• brownian_2d_data.txt, the data file.
• brownian_2d_plot.m, plots the data
• brownian_2d_plot.png, the plot.

BROWNIAN_ANIMATION animates Brownian motion by drawing one more step every 1/4 second of viewing time. Octave graphics comands are used.

• brownian_animation.m, simulates Brownian motion and displays the path in an animated way.
• brownian_animation.png, the final plot, showing the history of the motion.

BULGARIA_PLOT takes data about the Bulgarian population over time and makes a plot of (time,population). Octave graphics comands are used.

• bulgaria_data.txt, a data file; each line is a year and population count.
• bulgaria_plot.m, reads and plots the data.
• bulgaria_plot.png, the plot.

CAFFEINE_SCATTER seeks a relationship between the percentage of blindness due to cataracts, and the daily intake of caffeine, in a number of countries. A scatter plot is produced. Octave graphics comands are used.

• caffeine_data.txt, cataract percentage, and milligrams of caffeine.
• caffeine_scatter.m, reads and plots the data.
• caffeine_scatter.png, the plot.

CIRCLE_SCATTERS depicts 500 pairs of (X,Y) data points in the unit square, 395 of which lie inside the unit circle, and 105 outside. On a single graph, we display scatter plots of the inside points (blue), the outside points (red), and a line representing the perimeter of the circle. Octave graphics comands are used.

• circle1_data.txt, the coordinates of points inside the circle.
• circle2_data.txt, the coordinates of points outside the circle.
• circle_scatters.m, reads the data and makes a plot.
• circle_scatters.png, the plot.

CORKSCREW_PLOT3D generates (X,Y,Z) points on a curve, and makes a 3D line plot. Octave graphics comands are used.

• corkscrew_plot3d.m, generates data, saves it to a file, and makes a 3D plot.
• corkscrew_data.txt, a list of the (x,y,z) data values.
• corkscrew_plot3d.png, the plot.

CORVETTE_SCATTER considers the resale price for Corvettes by model year, displaying the results as a scatter plot. Octave graphics comands are used.

• corvette_data.txt, a data file; each line is a model year and asking price.
• corvette_scatter.m, reads and plots the data.
• corvette_scatter.png, the plot.

DRUG_DOSAGE_PLOTS depicts measurements over 48 hours of the blood level concentration of a medicinal drug. The drug needs to reach a certain level to have an effect, but must not exceed the toxic level. A graphic is created which shows, on one plot, the concentration over time, the minimal effective level, and the maximum nonlethal leval. Octave graphics comands are used.

• drug_dosage_data.txt, a data file of times and concentrations;
• drug_dosage_plots.m, reads the data, and plots the concentration level and two limiting straight lines.
• drug_dosage_plots.png, the plot.

GEYSER_BAR works with measurements of the waiting time in minutes between successive eruptions of the Old Faithful geyser. The data has been grouped into bins. The bin counts are displayed as a bar chart. Octave graphics comands are used.

• geyser_bar_data.txt, bin centers, and occupancy counts, for waiting times.
• geyser_bar.m, reads the data and makes a plot.
• geyser_bar.png, the plot.

GEYSER_HISTOGRAM contains the waiting time in minutes between successive eruptions of the Old Faithful geyser. Octave graphics comands are used.

• geyser_data.txt, waiting times and eruption durations.
• geyser_histogram.m, reads the data and makes a plot.
• geyser_histogram.png, the plot.

GEYSER_SCATTER looks for relations between the duration in minutes of the eruption and following waiting times for the Old Faithful geyser. Octave graphics comands are used.

• geyser_data.txt, waiting times and eruption durations.
• geyser_scatter.m, reads the data and makes a plot.
• geyser_scatter.png, the plot.

GRID_CONTOUR 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)). A color contour plot is created. Octave graphics comands are used.

• grid_data.txt, the data.
• grid_contour.m, reads the data and makes a plot.
• grid_contour.png, 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. Octave graphics comands are used.

• grid_data.txt, the data.
• grid_surface.m, reads the data and makes a plot.
• grid_surface.png, the plot.

INSECT_SCATTER3D involves 3 data sets, each containing 10 measurements of 3 quantities for each of 3 species of insect. The quantities are first tarsus width, second tarsus width, and maximum width of the aedeagus. It is of interest to know whether these three measurements are enough to differentiate between members of the three species. A 3D scatter plot is created. Octave graphics comands are used.

• insect_a_data.txt;
• insect_b_data.txt;
• insect_c_data.txt;
• insect_scatter3d.m, reads the 3 data sets, plots them as a 3D scatter plot, and saves a snapshot of the plot.
• insect_scatter3d.png, the plot.

IRIS_SUBPLOTS demonstrates the use of subplots. In this case, there are three varieties of iris, and for each, several specimens have been collected and measurements recorded for sepal length, sepal width, petal length and petal width. It is desired to create a 4x4 array of plots of each possible pair of variables. Moreover, data is to be color-coded by iris variety. Octave graphics comands are used.

• iris_setosa_data.txt, data set #1;
• iris_versicolor_data.txt, data set #2;
• iris_virginica_data.txt, data set #3;
• iris_subplots.m, reads the data, and makes the plot.
• iris_subplots.png, the plot.

LEAST_SQUARES_PLOTS compares 15 pairs of (x,y) data, the least squares line that approximates their behavior, and a quadratic curve that is much closer to the data. Octave graphics comands are used.

• least_squares1_data.txt, coordinates of the 15 sample points;
• least_squares2_data.txt, coordinates of two points on the least squares approximating line;
• least_squares3_data.txt, coordinates of points on the exact curve;
• least_squares_plots.m, reads data, makes the plot.
• least_squares_plots.png, the plot.

LISSAJOUS_PLOT records 1000 points on a Lissajous curve defined by x=sin(3*t+pi/2), y=sin(4t). The curve is to be plotted and every tenth point marked. Octave graphics comands are used.

• lissajous_data.txt, the data.
• lissajous_plot.m, reads the data and makes a plot.
• lissajous_plot.png, the plot.

LYNX_PLOT makes a line plot of the yearly lynx harvest from 1821 to 1934. Data points are marked by circles. Octave graphics comands are used.

• lynx_data.txt, a data file.
• lynx_plot.m, reads the data and makes a plot.
• lynx_plot.png, the plot.

MARIO_FILL makes a simple image of Mario, by constructing a grid of squares filled with color. Octave graphics comands are used.

• mario_fill.m, makes a plot.
• mario_fill.png, the plot.

NILE_HISTOGRAM makes a histogram of the yearly measurement of the height of the Nile at maximum flood. By lumping the data into bins, it is easier to see the range of flood heights, and the probability of various values in the range. Octave graphics comands are used.

• nile_data.txt, a list of index and flood height for each year.
• nile_histogram.m, reads data and makes a histogram.
• nile_histogram.png, the plot.

NILE_PLOT makes a line plot of the yearly measurement of the height of the Nile at maximum flood. Octave graphics comands are used.

• nile_data.txt, a list of index and flood height for each year.
• nile_plot.m, reads data and makes a line plot.
• nile_plot.png, the plot.

NINETY_HISTOGRAM considers 90 numeric values. We create a histogram, to see how the data spreads out across its range. We spot outliers as histogram bins of low occupancy that are far from the rest of the data. Octave graphics comands are used.

• ninety_data.txt, a text file containing a list of 90 numbers.
• ninety_histogram.m, reads the data and creates a histogram.
• ninety_histogram.png, the plot.

ORBITAL_CONTOUR records, on a 101x101 grid over [0,4*pi]x[0,4*pi], the minimum distance between two planets given a pair of orbital angles. The data is displayed as a color contour plot. Octave graphics comands are used.

• orbital_data.txt, a data file.
• orbital_contour.m, reads the data and makes a plot.
• orbital_contour.png, the plot.

PREDATOR_PLOT3D models the change in population over time of foxes and rabbit. A 3D line plot of prey, predator, and time values is made. Octave graphics comands are used.

• predator_plot3d.m, generates data, saves it to a file, and makes a 3D plot.
• predator_data.txt, a list of the (t,prey(t),pred(t)) data values.
• predator_plot3d.png, the plot.

PRESIDENT_HEIGHTS_BAR plots the heights of US presidents in inches, as a bar plot. Octave graphics comands are used.

• president_heights_data.txt, a data file;
• president_heights_bar.m, reads the data and makes a plot.
• president_heights_bar.png, the plot.

PRESIDENT_HEIGHTS_HISTOGRAM plots the heights of US presidents in inches, as a histogram. By grouping the data by height, we lose the ability to identify specific cases, but we are better able to see the range of heights, and to judge the frequency of various heights. Octave graphics comands are used.

• president_heights_data.csv, a data file;
• president_heights_histogram.m, reads the data and makes a plot.
• president_heights_histogram.png, the plot.

PRICE_PLOTS reads a table of average monthly prices for 11 consumer products, between February 2008 and February 2018, as compiled by the Bureau of Labor Statistics, and plots together the prices of three of the items. Octave graphics comands are used.

• price_data.csv, a CSV data file, with initial header line;
• price_data.txt, a data file;
• price_plots.m. read the data and make plots of some of it.
• price_plots.png, the plot.

RANDOM_SCATTER generates 500 pairs of (X,Y) data, which lie in the unit square, and tend to cluster around (0.5,0.5). Octave graphics comands are used.

• random_data.txt, the data file
• random_scatter.m, creates the data and displays a scatter plot.
• random_scatter.png, the plot.

SNOWFALL_HISTOGRAM makes a histogram of the yearly snowfall totals at Michigan Tech from 1890 to 2017. Octave graphics comands are used.

• snowfall_data.txt, the data.
• snowfall_histogram.m, reads the data and makes a histogram.
• snowfall_histogram.png, the plot.

SNOWFALL_PLOT makes a line plot of the snowfall at Michigan Tech from 1890 to 2017. Octave graphics comands are used.

• snowfall_data.txt, the data.
• snowfall_plot.m, reads the data and makes a plot.
• snowfall_plot.png, the plot.

SNOWFALL_SMOOTHED_PLOT uses the conv() command to compute a 10 year moving average of the snowfall at Michigan Tech from 1890 to 2017, and plots the smoothed data. Octave graphics comands are used.

• snowfall_data.txt, the data.
• snowfall_smoothed_plot.m, reads the data, smoothes it, and makes a plot.
• snowfall_smoothed_plot.png, the plot.

TEMPERATURE_SCATTER shows locations in the US where the January temperature was recorded. Octave graphics comands are used.

• temperature_data.txt, January temperature, -longitude, latitude.
• temperature_scatter.m, reads and plots the data.
• temperature_scatter.png, the plot.

TEMPERATURE_SCATTER3D shows temperatures and locations in the US where the January temperature was recorded. Octave graphics comands are used.

• temperature_data.txt, January temperature, -longitude, latitude.
• temperature_scatter3d.m, creates the data and displays a scatter plot.
• temperature_scatter3d.png, the plot.

TRACK_BAR considers an eye-tracking experiment in which the eye was focused on different regions for different durations. Each region has a text label. A bar graph is desired, in which the bar for each duration is given the appropriate label. Octave graphics comands are used.

• track_data.txt, a data file;
• track_bar.m, reads the data and makes a plot.
• track_bar.png, the plot.

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