plotScatter

Purpose

Creates a 2-dimensional scatter plot.

Format

plotScatter([myPlot, ]x, y)

plotScatter([myPlot, ]df, formula)

Parameters:

• myPlot (struct) – Optional argument, a plotControl structure.

• x (Nx1 or NxM matrix) – Each column contains the X values for a particular data point.

• y (Nx1 or NxM matrix) – Each column contains the Y values for a particular data point.

• df (NxM dataframe.) – The data referenced by the formula string.

• formula (string) –

  formula string describing which variables to plot. E.g "mpg ~ weight", will plot mpg along the y-axis and weight along the x-axis;

  E.g "age + education  ~ rating" will plot age and education along the y-axis against rating on the x-axis;

  E.g "education  ~ rating + by(gender)" will split the data by the gender variable and then plot both groups with education along the y-axis against rating on the x-axis;

Examples

Example 1: Formula string with the ‘by’ keyword

We can create the above image with the code below.

// Create file name with full path
fname = getGAUSSHome("examples/crabs.dta");

// Load all variables from the dataset
crabs = loadd(fname);

// Draw the scatter plot using your preference settings
plotScatter(crabs, "rear_width ~ body_depth + by(sex)");

Note that when using a formula string, the axis labels and legend are filled in automatically.

Example 2: Customized plot without formula string

// Create file name with full path
fname = getGAUSSHome("examples/crabs.dta");

// Load all variables from the dataset
crabs = loadd(fname);

// Declare plt to be a plotControl structure
// and fill with default settings for scatter
struct plotControl plt;
plt = plotGetDefaults("scatter");

plotSetTitle(&plt, "Blue and Orange Crab Measurements", "arial", 14);

// Axis labels
plotSetYLabel(&plt, "Frontal Lobe", "arial", 12);
plotSetXLabel(&plt, "Rear Width");

// Span the Y range from 0 to 20
plotSetYRange(&plt, 0, 20);

// Draw Y-ticks every 4 units starting at 0
plotSetYTicInterval(&plt, 4, 0);

// Create grid lines coming from the major ticks
// on the Y axis and color them dark gray
plotSetYGrid(&plt, "major", "dark gray");

// Draw plot
plotScatter(plt, crabs[.,"frontal_lobe"], crabs[.,"rear_width"]);

See also

Functions plotXY(), plotLogLog(), plotBox(), plotHistP()