r Replace only some table values with values from alternate table

Question

This is not a \"vlookup-and-fill-down\" question.

My source data is excellent at delivering all the data I need, just not in in a usable form. Recent changes in volume

Answer 1

Assuming you want to replace NAs in onPO with values from Backordered here is a solution using dplyr::left_join:

library(dplyr);
left_join(inv, svc) %>%
    mutate(onPO = ifelse(is.na(onPO), Backordered, onPO)) %>%
    select(-Backordered, -`Rcv'd`);
#         Item onHand demand onPO
#1    10100200    600   3300 2700
#2    10100201     NA     NA   20
#3    10100202     39     40    1
#4    10100203      0     40   40
#5    10100204     NA     NA  100
#6  10100205-A     NA     NA   18
#7    10100206     40     70   30
#8    10100207      0    126  126
#9    10100208      0     10   10
#10   10100209      0     10   10
#11   10100210      0    250  250

Or a solution in base R using merge:

inv$onPO <- with(merge(inv, svc, all.x = TRUE), ifelse(is.na(onPO), Backordered, onPO))

---

Or using coalesce instead of ifelse (thanks to @thelatemail):

library(dplyr);
left_join(inv, svc) %>%
    mutate(onPO = coalesce(onPO, Backordered)) %>%
    select(-Backordered, -`Rcv'd`);