[R] matching and extracting data

[Chuck Cleland]

On 11/27/2009 10:25 AM, ram basnet wrote:
> Dear all,
> I have querry on how to extract the data by matching between two data set where one has the same elements multiple times?
>  
> For example, I have two matrix X and Y.
>> X
>    [,1]    [,2]       [,3]
> 1  A     5          P
> 2  B      6         P
> 3  C     7         P
> 4  D     5         Q
> 5  E      6         Q
> 6  F      7         Q
> 7  G     5          R
> 8  H     6          R
> 9  I       7          S
> 10 J      5         S
> 11 K    6          T
> 12 L     7          T
>  
> and 
>  
>> Y       [,1]
> 1          P
> 2          Q
> 3          R
> 4          S
>  
> Now, I want to select and extract all the data of P, Q, R and S elements of column 3 of X matrix by matching with column 1 of Y matrix like below:
>  
>> [,1]   [,2]       [,3]
> 1  A     5          P
> 2  B      6         P
> 3  C     7         P
> 4  D     5         Q
> 5  E      6         Q
> 6  F      7         Q
> 7  G     5          R
> 8  H     6          R
> 9  I       7          S
> 10 J      5         S
>  
> I guess, the answer might be simple but i am not getting way to figure out. And, i have to select subset from very huge data set. So, i need some kinds of automated procedure.
> If some one can help me, it will be great

> subset(X, X[,3] %in% Y[,1])
      [,1] [,2] [,3]
 [1,] "A"  "5"  "P"
 [2,] "B"  "6"  "P"
 [3,] "C"  "7"  "P"
 [4,] "D"  "5"  "Q"
 [5,] "E"  "6"  "Q"
 [6,] "F"  "7"  "Q"
 [7,] "G"  "5"  "R"
 [8,] "H"  "6"  "R"
 [9,] "I"  "7"  "S"
[10,] "J"  "5"  "S"

> Thanks in advance.
>  
> Sincerely,
> Ram Kumar Basnet
>  
> 
> 
>       
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> 
> 
> 
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-- 
Chuck Cleland, Ph.D.
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