R help - Oct 2002 - X-Priority: 3 (Normal)

# you need to distinguish datatypes 'character' and 'numeric'

bindec <- function(
 b # a CHARACTER representing a binary number
){
as.i <- as.integer(unlist(strsplit(b,"")))
print(as.i)
fl <- 2^(floor(round(log10(as.numeric(b)),10)):0)  # convert b to numeric
print(fl)
dec <- sum(as.i * fl)
dec
}
> bindec("100000")
[1] 1 0 0 0 0 0
[1] 32 16  8  4  2  1
[1] 32

# Best


# Jens Oehlschl?gel

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Reid,

Thanks that you took up the challenge of this serious puzzle (the issue
masked a bug in one of my functions under 1.5.1, which was unmasked when
changing
to 1.6.1, however the issue is still in 1.6.1).

You are getting close. Your example might be seen as inconsistent, but not
as DOUBLY inconsistent. And your example will not differ between R1.5.1 and
R1.6.1. 

What if I tell you, that in my example
> is.na(a2[b])
[1] FALSE

whereas yours
> a <- rep(1,10)
> b <- 11
> a2 <- a
> is.na(a2[b])
[1] TRUE

in other words, you tell R to replace non-existent element no. 11 by NA, and
dynamic extension makes <a> different from <a2>.
In my case <b> DOES NOT SELECT AN NON-EXISTENT ELEMENT OF <a> (resp.
<a2>).

Any ideas?


Jens


BTW: Patrick, you guessed right: not a character a and numeric b

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