cs_sum() calculates the proportion of the organization
that falls within the specified group. Variables are joined
with &; not specifiying a variable (or setting it to NULL)
includes all of its values.
Arguments
- dt
[data.table]A distribution fromcs_dist()- vac, inf, symp, test, detect
[logical(1)]Variables values specifying which sub-group to sum over. IfNULL, will sum over all values.