Create columns from tagged words - r

Question

I have a vector with tagged words like c(#142#856#856.2#745, NA, #856#855, NA, #685, #663, #965.23, #855#658#744#122).
Words are separated by sharp. I would like create a data frame with one column for each different code, and then write 1 or 0 (or NA) depending if that code it is in that row or not.
The idea is that each element becomes a row, and each code becomes a column, and then if the code is in that element then in the column is marked with 1, or 0 if that code is not in that element.
ID | 142 | 856 |856.2 | ... | 122 |
1 | 1 | 1 | 1 | ... | 0 |
2 | 0 | 0 | 0 | ... | 0 |
...
I know how to do this with a complex algorithm plenty of loops. But, is it there any easy way to do this in a easy way?

Answer 1

You can accomplish this fairly easily using stringr:
# First we load the package
library(stringr)
# Then we create your example data vector
tagged_vector <- c('#142#856#856.2#745', NA, '#856#855', NA, '#685', '#663',
'#965.23', '#855#658#744#122')
# Next we need to get all the unique codes
# stringr's str_extract_all() can do this:
all_codes <- str_extract_all(string=tagged_vector, pattern='(?<=#)[0-9\\.]+')
# We just looked for one or more numbers and/or dots following a '#' character
# Now we just want the unique ones:
unique_codes <- unique(na.omit(unlist(all_codes)))
# Then we can use grepl() to check whether each code occurs in any element
# I've also used as.numeric() since you want 0/1 instead of TRUE/FALSE
result <- data.frame(sapply(unique_codes, function(x){
as.numeric(grepl(x, tagged_vector))
}))
# Then we add in your ID column and move it to the front:
result$ID <- 1:nrow(result)
result <- result[ , c(ncol(result), 1:(ncol(result)-1))]
The result is
ID X142 X856 X856.2 X745 X855 X685 X663 X965.23 X658 X744 X122
1 1 1 1 1 1 0 0 0 0 0 0 0
2 2 0 0 0 0 0 0 0 0 0 0 0
3 3 0 1 0 0 1 0 0 0 0 0 0
4 4 0 0 0 0 0 0 0 0 0 0 0
5 5 0 0 0 0 0 1 0 0 0 0 0
6 6 0 0 0 0 0 0 1 0 0 0 0
7 7 0 0 0 0 0 0 0 1 0 0 0
8 8 0 0 0 0 1 0 0 0 1 1 1
You may notice in the column names an "X" precedes each code. That's because in R a variable name may not begin with a number.