R data.table set new column with logical value if a weekday is between a date range

Question

I have a data.table object with two date columns, from and to. I want to create a new column to determine if a specific w

Answer 1

You could also try the foverlaps approach

First will create data set of all the Wednesday starting from min(from) and ending at max(to)

DateDT <- DT[, {
                temp <- seq(min(from), max(to), by = "day")
                temp2 <- temp[wday(temp) == 4L]
                .(from = temp2, to = temp2)
               }
             ]

Then run foverlaps and extract desired rows

indx <- foverlaps(DT, setkey(DateDT), nomatch = 0L, which = TRUE)$xid

Then a simple update by reference will do

DT[, flag := 0L][indx, flag := 1L]
DT[, table(flag)]
#  0  1 
# 44 57