For loop problems in r: Error in if (length[i] == 1) { : missing value where TRUE/FALSE needed

Question

ann <- 1:2500
len <- sample(1:3,1000,replace=TRUE)
df <- data.frame(col1= c(1:2500),col2= c(1:2500))

for (i in 1:length(ann)) {
      if (length[i]==1) { 
             


        

Answer 1

Here we can iterate through all the elements of len, and for each do an inner loop that takes that element of len and enters it into that many rows of df$col1.

df_row <- 1
for (i in 1:length(len)) {
  for (j in 1:len[i]) {
    df[df_row, 1] = len[i]
    df_row <- df_row + 1
  }
}