R - index position with the condition
I have a data frame like this
w<-c(0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0)
I want the index position starting after the value 1.
output : NA,NA,NA,NA,NA,1,2,3,4,5,6,7,1,2,3,4,5,1,2,3,4,5,6,7,8,9
ideally applicable to a data frame.
thank
edit: w is the dataframe,
about this function
m<-as.data.frame(w)
m[m!=1] <- row(m)[m!=1]
m
w
1 1
2 2
3 3
4 4
5 5
6 1
7 7
8 8
9 9
10 10
11 11
12 12
13 1
14 14
15 15
16 16
17 17
18 1
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
but falling back to 1 when 1 matches.
> m
w wanted
1 1 NA
2 2 NA
3 3 NA
4 4 NA
5 5 NA
6 1 1
7 7 2
8 8 3
9 9 4
10 10 5
11 11 6
12 12 7
13 1 1
14 14 2
15 15 3
16 16 4
17 17 5
18 1 1
19 19 2
20 20 3
21 21 4
22 22 5
23 23 6
24 24 7
25 25 8
26 26 9
thank
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2 answers
For data including re-1 and non-sequential input, the following works:
m[9,1] <- 100
m[3,1] <- 55
m[14,1] <- 60
m[14,1] <- 60
m[25,1] <- 1
m[19,1] <- 1
m$result <- 1:nrow(m) - which(m$w == 1)[cumsum(m$w == 1)] + 1
But if the data doesn't start at 1:
m[1,1] <- 2
Then this works:
firstone <- which(m$w == 1)[1]
subindex <- m[firstone:nrow(m),'w'] == 1
m$result <- c(rep(NA,firstone-1),1:length(subindex) - which(subindex)[cumsum(subindex)] + 1)
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