[R] converting string vector to integer/numeric vector

[David Winsemius]

So there is one item per line and the task is to recognize the strings  
"INT" and "NUM" and create variables with numeric type and

INT=c(2,3,4)
NUM=c(2.37, 4.56)  # ???

I worry that is not a full description of the task .... if there be  
more than just two variable names and if all the INTs have the same  
name, then they will get overwritten ....  but perhaps you have  
specified the problem completely, so here goes:

 > txt <- textConnection('INT
+ "2"
+ "3"
+ "4"
+
+ NUM
+ "2.37"
+ "4.56"')
 > indat <- read.table(txt, stringsAsFactors=FALSE)

 > indat$nflag <- as.numeric(indat$V1)
 > cumsum(is.na(indat$nflag))
[1] 1 1 1 1 2 2 2

 > by(indat$V1, cumsum(is.na(indat$nflag)), function(x)  
assign(as.character(x[1]), as.numeric(x[-1]) ,envir = .GlobalEnv) )
cumsum(is.na(indat$nflag)): 1
[1] 1 3 4
-------------------------------------------------------------
cumsum(is.na(indat$nflag)): 2
[1] 2 5
 > INT
[1] 1 3 4
 > NUM
[1] 2 5
.



On Sep 5, 2010, at 9:33 AM, rajesh j wrote:

> The string vector actually comes as a part of a list, and the vector  
> is named "int", and the numbers are strings. I then have to make it  
> a vector that is still called "int" and has 4,5,6 etc. the types are  
> either integer or numeric. The number of items in the vector is  
> unknown.
>
> here's an example,
>
> a list has vectors
>
> INT
> "2"
> "3"
> "4"
>
> NUM
> "2.37"
> "4.56"
>
>
>
> On Sun, Sep 5, 2010 at 6:56 PM, David Winsemius <dwinsemius at comcast.net 
> > wrote:
>
> On Sep 5, 2010, at 9:22 AM, rajesh j wrote:
>
>> for e.g., I get the following as a string vector
>> "int" "4" "5" "6"
>> after reading the first element, I have to convert this to a  
>> integer vector
>
> But what is the right answer?  And what number of items are possble  
> per line?  And what are the other possible type identifiers? We need  
> an example that has enough complexity to allow testing.
>
> -- 
> David.
>
>
>>
>> On Sun, Sep 5, 2010 at 6:44 PM, David Winsemius <dwinsemius at comcast.net 
>> > wrote:
>>
>> On Sep 5, 2010, at 8:48 AM, rajesh j wrote:
>>
>> Hi,
>>
>> Is it possible to convert a string vector to integer or numeric  
>> vector? In
>> my situation I receive data in a string vector and have to convert  
>> it based
>> on a given type.
>>
>> Can you give an example? I don't understand either what sort of  
>> conversion you desire or what you mean by "convert it based on a  
>> given type."
>>
>> There are a couple of function you may want to consider but I am  
>> having difficulty convincing myself they answer the problem posed:
>>
>> ?charToRaw
>> ?stroi
>>
>> > strtoi(charToRaw("123 this is a string"), base=16)   # convert to  
>> decimal ASCII
>>  [1]  49  50  51  32 116 104 105 115  32 105 115  32  97  32 115  
>> 116 114 105 110 103
>>
>> -- 
>>
>> David Winsemius, MD
>> West Hartford, CT
>>
>>
>>
>>
>> -- 
>> Rajesh.J
>>
>>
>
> David Winsemius, MD
> West Hartford, CT
>
>
>
>
> -- 
> Rajesh.J
>
>

David Winsemius, MD
West Hartford, CT