[R] R match - could be improved ?

[Jeff Newmiller]

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In no programming language is it a good idea to assume equality with floating point values. See FAQ 7.31. In cases like this use integers to create sequences and then generate floating point from them. Do not go fishing in floating point data for specific values.

Also, you seem to be using list objects for no apparent reason.

myvector1 <- c(1L:100L)

myvector3 <- seq(10L*myvector1[1], 10L*myvector1[ length(myvector1) ])

myvector4 <- seq(950L, 1000L)

myvector5 <- match(myvector4, myvector3)

I think the as.list is working because match is internally converting to character and comparing that... which makes the as.list solution rather inefficient art best.
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On March 15, 2015 4:04:29 AM PDT, Jeremy Clark <jeremyclarkbio at gmail.com> wrote:
>​Dear All,
>
>The following gives a very unpleasant experience with apparently random
>NAs
>- probably it's my bad formatting of the coding - but the effect is
>unexpected and if undetected can lead to considerable problems:
>
>myvector1 = NULL
>
>myvector3 = NULL
>
>myvector4 = NULL
>
>myvector5 = NULL
>
>
>
>myvector1 <- c(1:100)
>
>
>
>
>
>myvector3[[1]] <- seq(myvector1[1], myvector1["length"(myvector1)], by
>=
>0.01)
>
>myvector4[[1]] <- seq(95, 100, by = 0.01)
>
>
>
>myvector5[[1]] <- match(myvector4[[1]], myvector3[[1]])
>
>
>
>myvector5
>
>
>
>## A solution (but rather annoying):
>
>
>
>myvector5[[1]] <- match(as.list(myvector4[[1]]),
>as.list(myvector3[[1]]))
>
>myvector5
>​
>Could anyone tell me why the NAs occur ??
>
>Many thanks.​
>
>	[[alternative HTML version deleted]]
>
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