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Let‘say I have a TableA:

Code Description
001 Apple
002 Banana

I also have TableB:

Description
001
002
003

I want to replace the values in Description of TableB with values from Description of TableA.

I understand that I can do a simple join. But, I would like to replace values. How can I do that?

My possible solution is the following, but it does not work properly:

TableB$Description <- TableA[TableA$Code %in% TableB$Description, Description]
r2evans
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Meru Li
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2 Answers2

2

This could be a merge/join operation,

merge(TableB, TableA, by.x = "Description", by.y = "Code", all.x = TRUE)
#   Description Description.y
# 1           1         Apple
# 2           2        Banana
# 3           3          <NA>

(For more info on merge/join, see How to join (merge) data frames (inner, outer, left, right) and What's the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN and FULL JOIN?)

Or it could be a simple lookup using match:

TableA$Description[ match(TableB$Description, TableA$Code) ]
# [1] "Apple"  "Banana" NA
r2evans
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0

You could use the elucidate::translate() function, which provides a more readable syntax for the match() solution posted by r2evans.

tableA <- data.frame(code = c(001, 002),
                     Description = c("Apple", "Banana"))

tableB <- data.frame(Description = c(001, 002, 003))

tableB$Description <- translate(tableB$Description, old = tableA$code, new = tableA$Description)

tableB

> tableB
  Description
1       Apple
2      Banana
3        <NA>

The elucidate package can be installed with:

remotes::install_github("bcgov/elucidate")
huttoncp
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