How do you match a numeric value to a categorical value in another data set

Question

I have two data sets. One with a numeric value assigned to individual categorical variables (country name) and a second with survey responses including a person's nationality. How do I assign the numeric value to a new column in the survey dataset with matching nationality/country name?

Here is the head of data set 1 (my.data1):

    EN           HCI
1 South Korea  0.845
2 UK           0.781
3 USA          0.762

Here is the head of data set 2 (my.data2):

         Nationality OIS IR
1        South Korea   2  2
2        South Korea   3  3
3                USA   3  4
4                 UK   3  3

I would like to make it look like this:

         Nationality OIS IR   HCI
1        South Korea   2  2 0.845
2        South Korea   3  3 0.845
3                USA   3  4 0.762
4                 UK   3  3 0.781

I have tried this but unsuccessfully:

my.data2$HCI <- NA
for (i in i:nrow(my.data2)) {
  my.data2$HCI[i] <- my.data1$HCI[my.data1$EN == my.data2$Nationality[i]]
}

Does this answer your question? [How to join (merge) data frames (inner, outer, left, right)](https://stackoverflow.com/questions/1299871/how-to-join-merge-data-frames-inner-outer-left-right) — astrofunkswag, Mar 19 '20 at 18:20

score 0 · Accepted Answer · answered Mar 19 '20 at 17:52

0

We can use a left_join

library(dplyr)
left_join(my.data2, my.data1, by = c("Nationality" = "EN"))

Or with merge from base R

merge(my.data2, my.data1, by.x = c("Nationality", by.y = "EN", all.x = TRUE)

answered Mar 19 '20 at 17:52

akrun

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Worked perfectly! Thank you so much. – D_Provost Mar 19 '20 at 17:59

How do you match a numeric value to a categorical value in another data set

1 Answers1