合并数据框架不同的行和不同的列

Question

I have a data frame like this

df1

  a       b       c

  10      11    10
  00021   11    00021
  022     1     00021
  00054   32    00054

and another one like this

df1

  name     n

  10       1
  00021    2
  022      1
  00054    1

that counts how many times the variables in the column c of df1 appear. I would like to add to the first data frame one column like n in df2 ; I tried to merge the two data frame but without success..

Answer 1

You can use merge :

merge(df1, df2, by.x = "c", by.y = "name")

      c     a  b n
1 00021 00021 11 2
2 00021   022  1 2
3 00054 00054 32 1
4    10    10 11 1