counting the occurrence of substrings in a column in R with group by

Question

I would like to count the occurrences of a string in a column ....per group. In this case the string is often a substring in a character column.

I have some data e.

Answer 1

You can also use cSplit() from my "splitstackshape" package. Since this package also loads "data.table", you can then just use dcast() to tabulate the result.

Example:

library(splitstackshape)
cSplit(mydf, "String", direction = "long")[, dcast(.SD, village ~ String)]
# Using 'village' as value column. Use 'value.var' to override
# Aggregate function missing, defaulting to 'length'
#    village fd_sec ht_rm san NA
# 1:       A      1     2   0  1
# 2:       B      1     0   0  0
# 3:       C      0     1   1  0