Contour Plot

Contour plots display three-dimensional data using contour lines to indicate the magnitude of one numeric value for different combinations of two other numeric values.

To generate a contour plot

Choose Graph __image\arrow5.gif Three Variable__image\arrow5.gif Contour Plot. The dialog shown below appears.

Data page

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In the Contour Plot dialog, the Data page has the following options:

Data

Data Set

Select a data set from the dropdown list or type the name of a data set. You can also type into the Data Set edit field any expression that evaluates to a data set.

Subset Rows

Enter an S-PLUS expression that identifies the rows to use in the analysis. To use all the rows in the data set, leave this field blank.

Variables

X Axis Value

Specify the column containing x-axis values.

Y Axis Value

Specify the column containing y-axis values.

Z Axis Value

Specify the column containing z-axis values.

Conditioning

Select the columns specifying conditioning values.

Save Graph Object

Save As

Enter the name for the object in which to save the results of the analysis.

Plot page

__image\contour2.gif

In the Contour Plot dialog, the Plot page has the following options:

Interpolate

Interpolate to Grid Before Plotting

Check this to automatically interpolate the points to a grid. If the points are already gridded, this may be un-checked to avoid unnecessary computation.

X Grid Size

Number of grid levels on the x-axis.

Y Grid Size

Number of grid levels on the y-axis.

Contour Levels

Number of Cuts

Number of contour levels to display.

Use Pretty Contour Levels

Check this to create contour levels which are round numbers suitable for labeling.

Fills

Include Fills

Check this to include a grid of color fills.

Include Color Key

Check this to include a legend for the color fills.

Lines

Include Contour Lines

Check this to include contour lines.

Include Contour Labels

Check this include contour labels.

Titles page

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In the Contour Plot dialog, the Titles page has the following options:

Titles

Main Title

Specify a main title to add on the top of the page.

Subtitle

Specify a subtitle to add on the bottom of the page.

Labels

X Axis Label

Specify a label for the x-axis.

Y Axis Label

Specify a label for the y-axis.

Axes page

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In the Contour Plot dialog, the Axes page has the following options:

Aspect Ratio

Aspect Ratio This controls the size of the axis area within the designated plot area. Specify "Fill Plot Area" to fill the page, "Bank to 45 Degrees" to use the 45-degree banking rule in each panel, or "Specified Value" to specify a numeric value.

Ratio Value A numeric value indicating the ratio of height to width.

Scale

X Scale

The scale to use for placing tick marks on the x-axis.

Y Scale

The scale to use for placing tick marks on the y-axis.

Limits

X Limits

The limits for the x-axis. Specify a minimum and a maximum, separated by a comma. For example: "1, 10".

Y Limits

The limits for the y-axis. Specify a minimum and a maximum, separated by a comma. For example: "1, 10".

Relation

X Relation

Controls the relationship between the x-axes in different panels of a conditioned plot. The default value of "Same" ensures that the horizontal or vertical axes on each panel will be identical. "Sliced" gives the same number of data units to corresponding axes on each panel, ensuring that the number of units per cm. is identical. "Free" results in each panel having an axis that accommodates just the data in that panel. For "Sliced" and "Free", axes will be drawn for each panel, using more space on the display.

Y Relation

Controls the relationship between the y-axes in different panels of a conditioned plot.

Alternating

Alternating X Axes

Determines whether x-axes alternate from one side of the group of panels to the other.

Alternating Y Axes

Determines whether y-axes alternate from one side of the group of panels to the other.

Multipanel page

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In the Contour Plot dialog, the Multipanel page has the following options:

Layout

Number of Columns/Rows/Pages Control the layout of the panels by specifying the number of columns, rows and pages.

Panel Order Choose from Graph Order or Table Order. Graph Order begins drawing panels in the bottom left corner of the graph, to the right and up. Table Order begins drawing panels in the upper left corner and continues right.

Include Strip Labels Check this to include strip labels on panels.

Continuous Conditioning

Number of Panels If the data are continuous, the number of panels is determined by the number specified in this field.

Overlap Fraction Create overlapping intervals by specifying the fraction of data points that are shared across two panels.

Interval Type Choose from Equal Counts or Equal Ranges. Equal Counts places an equal number of data points in each plot. Equal Ranges makes the interval widths all equal.