[Rd] scale in stars() is not as documented (PR#1230)
maechler@stat.math.ethz.ch
maechler@stat.math.ethz.ch
Mon, 31 Dec 2001 14:40:04 +0100 (MET)
>>>>> "BDR" == Brian D Ripley <ripley@stats.ox.ac.uk> writes:
BDR> R 1.4.0 ?stars has
BDR> scale: logical flag: if `TRUE', the columns of the
BDR> data matrix are scaled independently so that the
BDR> maximum value in each column is 1 and the minimum is 0.
BDR> If `FALSE', the presumption is that the data have been
BDR> scaled by some other algorithm to the range [0,1].
BDR> but the code has
BDR> if (scale) { x <- sweep(x, 2, apply(x, 2, max), FUN
BDR> = "/") x[is.na(x)] <- 0 }
BDR> and so just linearly (not affinely) scales the maximum
BDR> to one. The result is very different star plots from
BDR> the S original. Try
BDR> stars(state.x77[, c(7, 4, 6, 2, 5, 3)])
BDR> compared to
BDR> stars(state.x77[, c(7, 4, 6, 2, 5, 3)], byrow = T) # in S
BDR> I suspect we should fix the code, but does anyone rely
BDR> on it?
BDR> BTW, it is hard to think of a more inefficient way to
BDR> write that scaling!
Thank you, Brian, for fixing it (for R-patched i.e. R 1.4.1 to be).
Note that the scale thing all came from the original
### T. Dye <tdye@lava.net>, July 1999
### This code started life as spatial star plots by David A. Andrews.
### See http://www.stat.rice.edu/~andrewsd/software/software.html.
(and that code was at least a start,..)
We had just done some (as you saw) `not quite perfect' NA handling.
Martin
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