R help - Aug 2009 - problem with pattern matching

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?

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?

Thanks
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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

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
IDs

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
> 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.
> 
> 
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