[R] problem with pattern matching

Rnewbie xuancj at yahoo.com
Wed Aug 5 11:36:05 CEST 2009

I wanted to extract my interested rows from a dataframe. I used:

grep(list$ID, dataframe$ID, value=T) #list contains a list of my interested

I got one match in return, which is the very first ID in list. It seems the
matching process just stopped, once the first match was found.

David Winsemius wrote:
> On Aug 4, 2009, at 11:16 AM, Rnewbie wrote:
>> dear all,
>> I got a problem with pattern matching using grep. I extracted a list  
>> of
>> characters from a data frame, and I tried to match this list of  
>> characters
>> to a column from another data frame. In return, I got only one  
>> match, but
>> there should be far more matches. Any ideas what has gone wrong?
> In general this falls into the category of  a request to "read my  
> mind". One, out of probably an infinite number, of ways to get such a  
> result is to use if()  when you needed ifelse().
>> Another question, if I also want to match the whole of the elements  
>> against
>> the non-initial parts of the elements in another table. Which  
>> command should
>> I use?
> Cannot even assign a semantic meaning to that one. What is are "non- 
> initial parts of the elements of another table"?
> ******************************************************************
>>  .... provide commented, minimal, self-contained, reproducible code.
> ******************************************************************
>> Thanks
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
> ______________________________________________
> 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.

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