The output from a loop is not correct - r

Question

I have two tables FDate and Task as follows:
FDate
Date Cycle Task
1: 1 90 D
2: 2 100 A
3: 3 130 B
4: 3 130 C
5: 4 180 <NA>
6: 5 200 A
7: 5 200 D
8: 6 230 <NA>
Task
Date Task
1 NA A
2 NA B
3 NA C
4 6 D
I want to write the Task name of same Date from table Task to table FDate. This is the code I try
for (i in 1:nrow(Task)) {
FDate$Task[FDate$Date %in% Task$Date[i]]<-Task$Task[i]
}
This is the output
Date Cycle Task
1: 1 90 D
2: 2 100 A
3: 3 130 B
4: 3 130 C
5: 4 180 <NA>
6: 5 200 A
7: 5 200 D
8: 6 230 4
I expect the output is D, not 4. I can't find what is wrong?

Answer 1

The issue is that the column is factor which gets coerced to integer storage mode value. Convert it to character before looping
FDate$Task <- as.character(FDate$Task)
Task$Task <- as.character(Task$Task)
Better, would be to use stringsAsFactors = FALSE either while reading (read.csv/read.table) or if we are creating with data.frame as in both cases, the default option is stringsAsFactors = TRUE and it can create some issues similar to this.
Also, this can be done with a join (assuming the datasets are data.table
library(data.tabl)
FDate[na.omit(df2), Task := i.Task,on = .(Date)]
FDate
# Date Cycle Task
#1: 1 90 D
#2: 2 100 A
#3: 3 130 B
#4: 3 130 C
#5: 4 180 <NA>
#6: 5 200 A
#7: 5 200 D
#8: 6 230 D
NOTE: changed the second data.table identifier to 'df2' instead of 'Task' as there is a column 'Task' in each dataset