Merge unequal dataframes and replace missing rows with 0

Question

I have two data.frames, one with only characters and the other one with characters and values.

df1 = data.frame(x=c('a', 'b', 'c', 'd', 'e'))

df2 = data.frame(x=c('a', 'b', 'c'),y = c(0,1,0))

merge(df1, df2)

  x y

1 a 0

2 b 1

3 c 0 

I want to merge df1 and df2. The characters a, b and c merged good and also have 0, 1, 0 but d and e have nothing. I want d and e also in the merge table, with the 0 0 conditions. Thus for every missing row at the df2 data.frame, the 0 must be placed in the df1 table, like:

  x y

1 a 0

2 b 1

3 c 0

4 d 0

5 e 0

Answer 1

To merge unequal data frames using merge function, you need to set the all argument of the merge function to TRUE to return NA for values that do not match.i.e.,

df1 = data.frame(x=c('a', 'b', 'c', 'd', 'e'))

df2 = data.frame(x=c('a', 'b', 'c'),y = c(0,1,0))

df <- merge(df1, df2, all = TRUE)

df[is.na(df)] <- 0  #To set NA to zero

df

  x y

1 a 0

2 b 1

3 c 0

4 d 0

5 e 0

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