Replicating values after a conditional statement is met?

Question

So this is some sample data I have:

signal1   signal2   signal3   
1         0         1        
1         1         1  
1         0         1  
1         0         1  
1         0         1  
1         0         1  
1         0         0 

And I want to add a fourth column, such that whenever signal1==signal2==signal3 are both 1, the new column repeats 1s until signal3 changes from 1 to 0.

So from the above example, I want to generate something like:

signal1   signal2   signal3   signal_generate
1         0         1         0
1         1         1         1
1         0         1         1
1         0         1         1
1         0         1         1
1         0         1         1
1         0         0         0

I'm thinking this would be achieved by an ifelse statement, but I'm having a lot of difficulty over this seemingly simple task. I'm thinking of doing something along the lines of:

signal_generate <- ifelse(data[,1]==data[,2]&data[,3]>0, rep(data[,3]==1), 0)

But I can't figure out how to get signal3 to repeat the correct number of times.

Edit: I'm realizing an ifelse would be silly because it would only look at rows in which the condition signal1 == signal2 == signal3 meet exactly. I'm still terribly stuck, and help would be much appreciated!

Answer 1

With help from Replacing NAs with latest non-NA value

I am not sure the initial conditions are handled correctly.

df <- read.table(text="
signal1   signal2   signal3   
1         0         1        
1         1         1  
1         0         1  
1         0         1  
1         0         1  
1         0         1  
1         0         0
", header=TRUE)

library(zoo)

# apply the logic using RowSums as a shortcut
df$triple <- as.integer((rowSums(df[,1:3])) == 3L)

# detect the change in signal and sett the initial condition
df$signal_change <- ifelse(df$triple == 1L, 1L, ifelse(df$signal3 == 0L, 0, NA))
df$signal_change[1] <- df$triple[1]

# generate the signal by carryign forward the changes
df$signal_generate <- na.locf(df2$signal_change, na.rm=FALSE)
df$signal_generate[1] <- df$signal_change[1]

df

#   signal1 signal2 signal3 triple signal_change signal_generate
# 1       1       0       1      0             0               0
# 2       1       1       1      1             1               1
# 3       1       0       1      0            NA               1
# 4       1       0       1      0            NA               1
# 5       1       0       1      0            NA               1
# 6       1       0       1      0            NA               1
# 7       1       0       0      0             0               0