19 `function`

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These packages (Note 1) are a one-person project undergoing rapid evolution. Backward compatibility (per Hadley Wickham) is provided as a courtesy rather than a guarantee.

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The function `function` creates an R function, i.e., an R object of S3 class 'function'. Note 19.1 summarizes the S3 methods for the class 'function' in the spatstat.* family of packages,

Note 19.1: S3 Methods for Class function in spatstat.* Packages (Table 8.1)

`S3` methods `*.function`
	visible	from	generic	isS4
`as.im.function`	TRUE	spatstat.geom	`spatstat.geom::as.im`	FALSE
`as.linim.function`	TRUE	spatstat.linnet	`spatstat.linnet::as.linim`	FALSE
`clusterfield.function`	TRUE	spatstat.random	`spatstat.random::clusterfield`	FALSE
`roc.function`	TRUE	spatstat.explore	`spatstat.explore::roc`	FALSE

Examples in Chapter 19 Require

library(groupedHyperframe)

19.1 Cumulative Average Vertical Height of Trapzoidal Integration

The S3 method visualize_vtrapz.function() (Section 11.3, Table 11.2)

checks, in the enclosing environment of the input function $f(x)$, for
- numeric vectors x, y, e.g., Listing 20.25; or
- a data frame z with columns $x and $y, e.g., Listing 20.27;
creates an $x$-grid using the numeric vector x (or z$x) and the number of equally spaced points with a default value of n=513L;
connects the $(x, f(x))$ dots at the $x$-grid;
scatter-plots the x (or z$x) and y (or z$y) dots.