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rfor-loopmatchseq

Use for loop to take steps of 15 and match vector to dataframe column

I have a series of numbers that are 0 or 1. total length is 35115 or if you take 35115/15 you have 2341 blocks. I want to step through each block and see if my vector tmp matches the column of interest that contains the blocks. I want to seq along my dataframe, but take steps of 15 and ask does these 15 match my vector. What am I doing wrong? can someone help me? Thank you all for teaching me something useful. Cheers

x;
        V1       V2 V3 V4  V5 V6 V7
 3R 11024348  A  G  A1  0 61
 3R 11024348  A  G  A2  1 30
 3R 11024348  A  G  A3  0 68
 3R 11024348  A  G  A4  0 57
 3R 11024348  A  G  A5  0 63
 3R 11024348  A  G  A6  0 49
 3R 11024348  A  G  A7  0 60
 3R 11024348  A  G  B1  0 63
 3R 11024348  A  G  B2  0 64
 3R 11024348  A  G  B3  0 71
 3R 11024348  A  G  B4  1 51
 3R 11024348  A  G  B5  0 37
 3R 11024348  A  G  B6  0 52
 3R 11024348  A  G  B7  0 47
 3R 11024348  A  G AB8  0 83
 3R 11024410  C  T  A1  0 45
 3R 11024410  C  T  A2  1 54
 3R 11024410  C  T  A3  0 76
 3R 11024410  C  T  A4  0 48
 3R 11024410  C  T  A5  0 49
 3R 11024410  C  T  A6  1 48
 3R 11024410  C  T  A7  0 45
 3R 11024410  C  T  B1  0 48
 3R 11024410  C  T  B2  0 81
 3R 11024410  C  T  B3  1 58
 3R 11024410  C  T  B4  1 50
 3R 11024410  C  T  B5  0 65
 3R 11024410  C  T  B6  1 45
 3R 11024410  C  T  B7  0 66
 3R 11024410  C  T AB8  0 58


tmp<-c(1,1,0,1,1,1,1,1,1,1,1,1,0,0,0)
for(i in seq(from=1, to=length(X$V6), by=15)){print(matchID<-match(tmp,X$V6[i]))}
Solution

  • If you really want to use a for loop, you need to define a datastructure in order to store your loop results (could be a vector of numbers, strings, list, matrix, etc).

    something like matchID<-vector()

    let's look at your code: 

    for(i in seq(from=1, to=length(X$V6), by=15)){print(matchID<-match(tmp,X$V6[i]))}

    your for function calls a loop from 1 to 30 (length of V6) jump by 15 (length of tmp), so it is going to return:

    >for(i in seq(1,30,15)) print(i)
[1] 1
[1] 16

    so if you index your V6 vector by i, the loop will only return the value at 1 and 16.

    Here is my solution:

    matchID<-vector() # stores the loop return in a vector
for(i in 1:length(x[, "V6"]){  
  matchID[i]<- as.numeric(tmp == x[, "V6"])[i]
}

    you can see that for ith element in matchID, it always equals to the ith element in the vector comparing temp and "V6".

    However, you really don't need a loop in this case

    matchID<-as.numeric(tmp == x[, "V6"])