Error in `$<-.data.frame`(`*tmp*`, “mode”, value = list(2L, 3L)) : replacement has 2 rows, data has 1

Question

I have a data frame called New. using this data frame, I need to create a data frame using for loop and if-else condition

the New data frame is as follows

no    mode    start    end
1     S       0.026    33.059
2     T       33.176   38.057 
3     S       38.202   40.082
4     T       40.145   51.160
5     S       51.272   52.254
6     T       52.274   56.238
7     S       56.359   57.259
8     T       57.396   62.280
9     S       62.454   69.270

and the required data frame should be in the following form ie if mode "S" and its difference is <=1 (end-start),

no    mode    start    end
1     S       0.026    33.059
2     T       33.176   38.057 
3     S       38.202   40.082
4     T       40.145   62.280
5     S       62.454   69.270

for this, I am using the following code,

mode <- 0
start <- 0
end <- 0
abc <- data.frame(mode, start, end)
for (i in 1:nrow(New)) {
   if((New[i,2] = "S" && New[i,4]-New[i,3])>1) abc$mode[i] = New[i,2]
   else
 abc$mode[i] = New[i-1,2]
   if((New[i,2] = "S" && New[i,4]-New[i,3])>1) abc$start[i] = New[i,3]
   else
 abc$start[i] = New[i-1,3]
   if((New[i,2] = "S" && New[i,4]-New[i,3])>1) abc$end[i] = New[i,4]
   else
 abc$end[i] = New[i,4]
   }

i am getting the following error

Error in "S" && New[i, 4] - New[i, 3] : invalid 'x' type in 'x && y'

thanks in advance

Answer 1

I think you can do away with the loop and the if s

New <- read.table(text="
no    mode    start    end
1     S       0.026    33.059
2     T       33.176   38.057 
3     S       38.202   40.082
4     T       40.145   51.160
5     S       51.272   52.254
6     T       52.274   56.238
7     S       56.359   57.259
8     T       57.396   62.280
9     S       62.454   69.270", 
header=TRUE, stringsAsFactors=FALSE)

abc <- New[New$mode == "S" & New$end - New$start <= 1, ]

abc
#   no mode start  end
# 5  5    S  51.3 52.3
# 7  7    S  56.4 57.3