Hello,
The function I included converts signed binary numbers into their
decimal representation. They are negative if a) they are multiples of 8
bits and b) the most significant bit is a "1". If not just convert to
integer.
As for a) above, I assume that you will have 8 bit numbers. And the
conversion is done as follows:
input: 10110010
splitting, to make it more clear:
1 0 1 1 0 0 1 0 - input
0 1 0 0 1 1 0 1 - reversed
1 - add 1 to the number with reversed bits
0 1 0 0 1 1 1 0 - result is the two's complement
c(0, 1, 0, 0, 1, 1, 1, 0) %*% 2^(7:0) is 78
But the msb is "1" so it's -78
This is what the function does, but instead of %*% it uses
sum(two's compl * powers of two)
Hope this helps,
Rui Barradas
The input must be a character string or character vector.
Às 14:36 de 20/01/20, Paul Bernal escreveu:
Dear friend Rui,
Hope you are doing great, thanks for your kind feedback. The challenge I
currently have at hand is to decode AIS messages and obtain latitude and
longitude values from those.
So basically, I want to accomplish something like in the example below.
I want to convert this binary number (10110010) into the two´s
complement representation, there is the logic they are using for that.
Since longitude ranges from
Example of conversion to decimal of a signed binary number in
two's complement representation
Let's convert to decimal the following signed binary number: 10110010
10110010 = -1×27 + 0×26 + 1×25 + 1×24 + 0×23 + 0×22 + 1×21 + 0×20 = -128
+ 32 + 16 + 2 = -78.
El lun., 20 ene. 2020 a las 7:22, Rui Barradas (<ruipbarra...@sapo.pt
<mailto:ruipbarra...@sapo.pt>>) escribió:
Sorry, missunderstood the problem.
Here it goes:
fun <- function(x){
res <- sapply(x, function(y){
if(nchar(y) %% 8 != 0 || substr(y, 1, 1) == "0"){
strtoi(y, base = 2)
}else{
y <- unlist(strsplit(y, ""))
-sum((y != "1")*2^((length(y) - 1):0)) - 1
}
})
unname(res)
}
fun("10110010")
fun("10000000")
fun(c("01000000", "01111111", "10110010", "10000000"))
Hope this helps,
Rui Barradas
Às 11:38 de 20/01/20, Rui Barradas escreveu:
> Hello,
>
> Is this what you want?
>
>
> x <- "10110010"
> strtoi(x, base = 2)
> #[1] 178
>
>
> Hope this helps,
>
> Rui Barradas
>
> Às 16:31 de 16/01/20, Paul Bernal escreveu:
>> Dear friends,
>>
>> How can I convert the following binary number in two´s complement
>> representation in R?
>>
>> 10110010
>>
>> Any help and/or guidance will be greatly appreciated,
>>
>> Best regards,
>>
>> Paul
>>
>> [[alternative HTML version deleted]]
>>
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>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
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-- To UNSUBSCRIBE and more, see
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> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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