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I have a character word matrix (3 by 3) and a dictionary (n by 1). I want to find the characters match with the dictionary, will be replaced by the character position exists in the dictionary and all the unmatched words will be removed (either NA, or NULL). I have tried simple pmatch, but it is not working. I am looking for the result like this, 

1    5    2
1    4    NA
3    NA   2

but getting result in this way, [1] 1 NA 3 5 4 NA 2 NA NA

I tried the code bellow,

a <- matrix(c("456_rr", "432_uu", "522_kk", "456_rr", "432_tt", "522", "456_ss", "432", "522_kk"), nrow = 3, ncol = 3, byrow = TRUE) # WordTable

b <- matrix(c("456_rr","522_kk","456_ss", "432_tt", "432_uu"), nrow = 5, ncol = 1) # Dictionary

c <- pmatch(a, b)

print(c)
bim
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  • ufs, thanks @akrun . but still far from expected result. And how to keep it matrix wise? – bim Mar 31 '16 at 07:00
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    I just updated with a solution. You can convert it to matrix either by calling `matrix` or use the `dim`. Are you sure that the values in the expected are correct? – akrun Mar 31 '16 at 07:01
  • Let me know if that is a typo. Or else I will delete my answer – akrun Mar 31 '16 at 07:02
  • That was a typo, your answer is right – bim Mar 31 '16 at 07:09

1 Answers1

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The nrow in the 'b' is not correct. It should be 5

b <- matrix(c("456_rr","522_kk","456_ss", "432_tt", 
     "432_uu"), nrow = 5, ncol = 1) 
v1 <- pmatch(a,b)
m1 
#[1]  1 NA  3  5  4 NA  2 NA NA

dim(m1) <- dim(a)
m1
#     [,1] [,2] [,3]
#[1,]    1    5    2
#[2,]   NA    4   NA
#[3,]    3   NA   NA

If we need to get the index of duplicates, use duplicates.ok=TRUE which is by default FALSE

`dim<-`(pmatch(a, b, duplicates.ok=TRUE), dim(a))
#     [,1] [,2] [,3]
#[1,]    1    5    2
#[2,]    1    4    2
#[3,]    3   NA    2
akrun
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  • thanks @akrun for this big help, but still it is not the expected positions from the dictionary. Is it the limitation of `pmatch`? – bim Mar 31 '16 at 07:08
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    @Noah changed the output. We need to add `duplicates.ok` – akrun Mar 31 '16 at 07:26