Merging dataframes in R

Question

I have two dataframes. One is like the following

> head(df1)
  dropOffZip hour transition Day7
1      622    0     72  1
2      04745    0      1  1
3      05823    0      1  1
4      06490    0      1  2
5      06807    0      1  2

And the second one is like following :

head(df2)
  dropOffZip Day7 hour Median Count
1     622    1   0     60     1
2     622    2    8     60     1
3     622    3    8     60     1
4     622    7   12     60     1

Now I want to make df3 by merging df1 and df2 based on common value for dropOffZip , Day7 and hour . The issue is while all the combination of day, hour, dropOffZip are available in df1, it's not the case for df2. So, in the merged df3, I still want to have rows for those combinations missing in df1, but the corresponding value for Median and Count should be assigned 0 . Could anyone suggest how to achieve this merging?

The final df3 should be like :

>head(df3)
  dropOffZip Day7 hour Median Count Transition
1     622     1    0    60      1      72
2     04745   1    0    0       0      1

Here the second row gives Median = 0 and Count = 0 because we don't have any column for dropOffZip 04745 in data frame df2

Answer 1

Try giving all = TRUE in merge and remove the unwanted NA using complete.cases(df3). Else add a new column called median and assign it to NA. Just rbind it and remove the unwanted rows with NA using complete.cases.