[R] R-help: grep in for loop using index - doesn't work

[Mohan Singh]

Thanks very much Phil :)

Worked prefect

-----Original Message-----
From: Phil Spector [mailto:spector at stat.berkeley.edu] 
Sent: Wednesday, March 11, 2009 11:14 PM
To: Mohan Singh
Subject: Re: [R] R-help: grep in for loop using index - doesn't work

Mohan -
    Sorry about that.  I need to check what I write
more carefully when I don't have any data available
to test it.
    I think what you want is

apply(data,2,grep,pattern='Query Item')

It will return a list with one element for each column, showing
the positiions where 'Query Item' was found.
                                          - Phil




On Wed, 11 Mar 2009, Mohan Singh wrote:

> Thanks Phil.
>
> That worked.
>
> The apply(..) commands gives me a single 1/0 output for each column which
> has the query item or not.
>
> But I am looking to find the index i from the loop to extract that
> particular value for plotting
>
> I'll try to improve the data.frame part; I was not able to access the rows
> with data (just started R), so I created individual frames for data
>
> Cheers
> Mohan
>
>
> -----Original Message-----
> From: Phil Spector [mailto:spector at stat.berkeley.edu]
> Sent: Wednesday, March 11, 2009 10:46 PM
> To: Mohan Singh
> Subject: Re: [R] R-help: grep in for loop using index - doesn't work
>
> Mohan -
>    "i" is the literal character i.  i is the variable called
> i.  In this case, you want the variable, i.e. i:
>
>   p1 <- grep("QueryItem",c1data[i,],value=FALSE,fixed=FALSE)
>
> I might also mention that creating a separate data frame for each
> column of your data is not really a good idea.  I believe that you're
> looking for a solution like
>
>     apply(data,2,grep,"Query Item")
>
> but it's hard to tell.  You might want to run that command
> and see if what you want is in the output.
>
>                                        - Phil Spector
> 					 Statistical Computing Facility
> 					 Department of Statistics
> 					 UC Berkeley
> 					 spector at stat.berkeley.edu
>
>
>
>
>
> On Wed, 11 Mar 2009, Mohan Singh wrote:
>
>> Hi everyone
>>
>>
>>
>>  I am trying to use grep in a for loop to compare a string value. It
works
>> if I use the actual index value but when I use the for loop index, it
>> doesn't work. Any suggestions plz.
>>
>>
>>
>> Here is the code:
>>
>>
>>
>> data <- read.table(file="Sigmoid.csv", head=FALSE, sep=",");
>>
>>
>>
>> c1 <- data$V1
>>
>> c2 <- data$V2
>>
>> c3 <- data$V3
>>
>>
>>
>> c1data <- data.frame(c1);
>>
>> c2data <- data.frame(c2);
>>
>> c3data <- data.frame(c3);
>>
>>
>>
>> #this works
>>
>> p <- grep("QueryItem",c1data["147",],value=FALSE,fixed=FALSE)
>>
>> print(p) # print 1
>>
>>
>>
>> #doesn't work
>>
>> i<-147
>>
>> p1 <- grep("QueryItem",c1data["i",],value=FALSE,fixed=FALSE)
>>
>> print(p1) # prints 0
>>
>>
>>
>> for(i in 137:270) {
>>
>>  print(i)
>>
>>  p <- grep("QueryItem",c1data["i",],value=FALSE,fixed=FALSE)
>>
>>  p2 <- p
>>
>>  print(p2)
>>
>>  if(length(p)>0) { print(p) }
>>
>> }
>>
>>
>>
>>
>> 	[[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>