How to compare specific columns with unequal length datasets in R?

Question

I have two datasets with few identical columns (block, number). One dataset has more number of rows that the other. I want to identify only those rows that differ between the two sets.

block <- c(1:10)
number <- c(1:10)
tray <- c(1:10)

df1 <- data.frame(block, number, tray)

block <- c(1:12)
number <- c(1:12)
key <- c(1:12)

df2 <- data.frame(block, number, key)

If I use library(compare) compare(df1, df2) It generates all FALSE..probably because they differ in one of the three columns. I only want it to compare via block and numebr to get that it differs in block 11, 12 number 11, 12

@akrun What if I wanted to directly merge df1 to df2 by block, number, key regardless of unequal length? I know I can't do merge alone. — Rspacer, Jan 07 '20 at 23:39

score 1 · Accepted Answer · answered Jan 07 '20 at 22:31

1

You can do it using anti_join from dplyr:

dplyr::anti_join(df2, df1, by = c("block", "number"))

#   block number key
#1    11     11  11
#2    12     12  12

answered Jan 07 '20 at 22:31

sm925

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How to compare specific columns with unequal length datasets in R?

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