[R] Odp: Problem in converting natural numbers to bits and others

[Vincent Goulet]

Le mer. 21 mai à 04:38, Petr PIKAL a écrit :

> Hallo
>
> r-help-bounces at r-project.org napsal dne 21.05.2008 09:42:40:
>
>> Hi,
>>
>> I just started using R for about one week and I have few problems.
>>
>> i)I have a problem in finding right function to convert a table of
> natural
>> numbers to bitwise. For a simple example;
>>
>> I have the below table:-
>>
>> Column  Col1   Col2   Col3
>> Sample1 5        7      10
>> Sample2 0        2       1
>> Sample3 4         0       0
>>
>>
>> Supposedly i wanted to convert to :-
>>
>>
>> Column  Col1   Col2   Col3
>> Sample1 1        1       1
>> Sample2 0        1       1
>> Sample3 1         0       0
>
> data<-read.table("clipboard", header=T
> If data is your data frame,
>
> data.bit<-data.frame(column=data[,1],(data[,-1]>0)*1)

sign(data) will also do.

Vincent

>
>
>>
>> ii)Besides, I would like to create a formula of Sum(3*(Element in  
>> each
>> column for a row))..does it equivalent to 3*(data[1:3,1:2]) in this
> case?or
>> I need to have Sum(3*(data[1:3,1:2])). Basically I wanted to mutliply
> each
>> element of column table of a row and sum it  up.
>
> Rather complicated.
>
>> 3*(data[1:3,2:3])
>  Col1 Col2
> 1   15   21
> 2    0    6
> 3   12    0
>> sum(3*(data[1:3,2:3]))
> [1] 54
>
> Works but I am suspicious that you wont something else.
>
>
>>
>> iii)I would also like to know how to insert an if else statement  
>> where
> in
>> the above case, I wanted to check if data[1:3,]
>> returns me 1 or 0, it will execute some calculations.
>> I refer to the R intro pdf and it mentioned using if (expr_1 ) expr_2
> else
>> expr_3. Does that mean if(data[1:3,1:2])>0 output[1:3,1:2]=0
>> else output[1:3,1:2]="100". If I did this command, how does R knows
> which
>> row and column to map the output with?
>
> If ... else ... is usually for working as programming steps
>
> ifelse(..., ..., ...)
>
> works with objects and is parts. You shall think first how to do your
> calculations with whole objects, it is usually more effective.
>
> Regards
> Petr
>
>>
>> Please advise. Appreciate alot. Thanks.
>>
>>   [[alternative HTML version deleted]]
>>
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> http://www.R-project.org/posting-guide.html
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>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.