Tracking what and how oberservations changed between two dataframes

Question

I have the following data:

x <- c("aaa", "bbb", "ccc", "ddd", "eee")
y <- c(1, 0, 0, 1, 1)
df1 <- data.frame(x,y)
x <- c("aaa", "bbb", "ccc", "ddd", "eee")
y <- c(1, 1, 1, 1, 0)
df2 <- data.frame(x,y)

Structure:

> df1
    x y
1 aaa 1
2 bbb 0
3 ccc 0
4 ddd 1
5 eee 1
> df2
    x y
1 aaa 1
2 bbb 1
3 ccc 1
4 ddd 1
5 eee 0

I'd like to track changes between df1 and df2.

If I anti_join(df2,df1) I can keep the things that have changed:

x   y
eee 0
ccc 1
bbb 1

But I want to know WHAT and HOW things changed from df1 to df2. For example:

x   y.from  y.to
eee 1       0
ccc 0       1
bbb 0       1

Thanks in advance.

Answer 1

Piggy backing off @zx8754 here is a hacky dplyr version using filter():

library(dplyr)
df3 <- merge(df1,df2,by="x") %>%
       filter(y.x != x.x)

#     x y.x y.y
# 2 bbb   0   1
# 3 ccc   0   1
# 5 eee   1   0

Answer 2

Here's a similar data.table approach

library(data.table)
setkey(setDT(df1), x)
df1[df2][y != i.y]
#      x y i.y
# 1: bbb 0   1
# 2: ccc 0   1
# 3: eee 1   0

Answer 3

You can try

index<-(df1$y!=df2$y)
cbind(df1[index,], df2[index,"y"])

Answer 4

Try this:

#merge on column x
df3 <- merge(df1,df2,by="x")

#show the change
df3[ df3[,2] != df3[,3],]
#     x y.x y.y
# 2 bbb   0   1
# 3 ccc   0   1
# 5 eee   1   0