CODEWITHSUNDEEP
rdataframe
Jeet
Jeet

Reputation: 188

R logic for replacing every zero occurring before 1

I am trying to build an iterative logic to achieve something but I am somehow failing in doing so:

I have the following data 

Identifier   A   B   C   D   E   F   G   H   I
---------  ---  --  --  --  --  --  --  --  --
1           0    0   0   0   0   0   1   0   0
2           0    0   1   0   1   0   0   1   1
3           0    0   0   0   0   0   1   1   1

I want to replace all the zeros occurring before the first 1 with "N" in each row and leave the rest of the 0's and 1's as it is.

This is the desired output

Identifier   A   B   C   D   E   F   G   H   I
---------  ---  --  --  --  --  --  --  --  --
1           N    N   N   N   N   N   1   0   0
2           N    N   1   0   1   0   0   1   1
3           N    N   N   N   N   N   1   1   1

I was trying out this code but it did not give me desired results

for (i in 1:nrow(test1)) {
  for (j in 2:9){
    if(test1[i,j]==0){
      k <- i
    }
    for(l in 1:k){
      test1[l,j]=3
    }
  }
}

Can anyone help me out here?

Upvotes: 2

Views: 50

Answers (2)

Cettt
Cettt

Reputation: 11981

since you did not mention your data format I will provide an answer for matrices:

You can use the apply function like this:

m <- matrix(c(0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,0,1,1,0,0,0,0,0,0,1,1,1), 3, 9, byrow = T)

myfun <- function(x) {
  idx = min(which(x == 1))-1 
  x[1:idx] <- "N"
  return(x)
}

t(apply(m, 1, myfun))

     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
[1,] "N"  "N"  "N"  "N"  "N"  "N"  "1"  "0"  "0" 
[2,] "N"  "N"  "1"  "0"  "1"  "0"  "0"  "1"  "1" 
[3,] "N"  "N"  "N"  "N"  "N"  "N"  "1"  "1"  "1"

Upvotes: 2

akrun
akrun

Reputation: 887098

We can use apply

df1[-1] <- t(apply(df1[-1], 1, function(x) replace(x, cumsum(x == 1) ==0, "N")))

Or using rowCumsums from matrixStats

library(matrixStats)
df1[-1][rowCumsums(as.matrix(df1[-1])) == 0] <- "N"

df1
#  Identfier A B C D E F G H I
#1         1 N N N N N N 1 0 0
#2         2 N N 1 0 1 0 0 1 1
#3         3 N N N N N N 1 1 1

data

df1 <- structure(list(Identfier = 1:3, A = c(0L, 0L, 0L), B = c(0L, 
0L, 0L), C = c(0L, 1L, 0L), D = c(0L, 0L, 0L), E = c(0L, 1L, 
0L), F = c(0L, 0L, 0L), G = c(1L, 0L, 1L), H = c(0L, 1L, 1L), 
    I = c(0L, 1L, 1L)), class = "data.frame", row.names = c(NA, 
-3L))

Upvotes: 4

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