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Step-by-Step Programming with Base SAS 9.4, Second Edition, 2nd Edition by SAS Institute

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Plotting One Set of Variables
Understanding the PLOT Statement
The PLOT procedure produces two-dimensional graphs that plot one variable against
another within a set of coordinate axes. The coordinates of each point on the plot
correspond to the values of two variables. Graphs are automatically scaled to the values
of your data, although you can control the scale by specifying the coordinate axes.
You can create a simple two-dimensional plot for one set of measures by using the
following PLOT statement:
PROC PLOT <DATA=SAS-data-set>;
PLOT vertical*horizontal;
where vertical is the name of the variable to plot on the vertical axis and horizontal is the
name of the variable to plot on the horizontal axis.
By default, PROC PLOT selects plotting symbols. The data determines the labels for the
axes, the values of the axes, and the values of the tick marks. The plot displays the
following:
the name of the vertical variable that is next to the vertical axis and the name of the
horizontal variable that is beneath the horizontal axis
the axes and the tick marks that are based on evenly spaced intervals
the letter A as the plotting symbol to indicate one observation; the letter B as the
plotting symbol if two observations coincide; the letter C if three coincide, and so on
a legend with the name of the variables in the plot and meaning of the plotting
symbols
The following display shows the axes, values, and tick marks on a plot.
Figure 30.2 Diagram of Axes, Values, and Tick Marks
vertical
axis
horizontal axis
value
tick marks
20
10
2 4 8 10 12
Note: PROC PLOT is an interactive procedure. After you issue the PROC PLOT
statement, you can continue to submit any statements that are valid with the
Plotting One Set of Variables 535
procedure without resubmitting the PROC statement. Therefore, you can easily and
quickly experiment with changing labels, values for tick marks, and so on.
Example
The following program uses the PLOT statement to create a simple plot that shows the
trend in high Dow Jones values from 1968 to 2008:
proc plot data=highlow;
plot DowJonesHigh*Year;
title 'Dow Jones Industrial Average Yearly High';
run;
The following output shows the plot:
Figure 30.3 Using a Simple Plot to Show Data Trends
The plot graphically depicts the exponential trend in the high value of the Dow Jones
Industrial Average over the past 50 years. The greatest growth has occurred in the past
10 years, increasing by almost 6,000 points.
536 Chapter 30 Plotting the Relationship between Variables

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