Methods for function head() about spatstat HOT 5 CLOSED

OK. That seems reasonable for list-like objects such as ppp, psp, lpp, solist, ..
But if X is an owin, what should head(X) return?

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In the book we suggest using head(as.data.frame(X)) to get the first few entries of X where X could be a point pattern, etc. Do we want head(X) to be equivalent, or something different?

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I suggest that the result of head(X) should have the same class as X where possible. So head.ppp would be like head.default except that it would use npoints to determine the appropriate number of points to extract.

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I think we should ignoreowin. If you use head on an owin you get an error as you deserve :-)

A solist is already handled correctly by head.default. To handle ppp, lpp and psp we could even mask head.default with the following function:

head.default <- function (x, n = 6L, ...){
    stopifnot(length(n) == 1L)
    spst <- inherits(x, c("ppp", "lpp", "psp")
    length_x <- if(spst) nrow(coords(x)) else length(x)
    n <- if (n < 0L) 
        max(length_x + n, 0L)
    else min(n, length_x)
    x[seq_len(n)]
}

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Done (in spatstat 1.47-0.055) using nobjects

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