Noob is sorry for the question, but in reality I do not know where to find me for this process that I should do. My problem is that I need to get the value of the second column in all the matches in the second column. Any kind of merge but in this case I have several repeating values in the correct database, so I need all the matches.
To be clear: Suppose I have such a data frame:
df < -data.frame (CustomerId = c ("a", "b", "c", "h")) 1 a 2 b3c4h and my other dataframe Something like this will happen:
df2 & lt; -data.frame (customer ID = C ("a", "b", "b", "b", "a", "d", "c"), code = c (1,2,2,3, 2,4,4) Customer ID code 1A1 2B2 3B2 4B3A2 6D4 7C4 Let me "merge" this two dataframes There is a need to do so that I can get all the code for each customer ID. I'll need something like this:
Customer ID code 1 one 1,2 2B 2,3 3C4 4H NA I Found problems are:
- Repeated several times on the crossing dataframe
- I can use a loop but my database is so large that I avoid inefficiency
- The amount of time that the customer ID can be repeated on the second datafile variable
- This can be That repeats one of the customer ID multiple times but there is only one code, so I will only need one code, not all of them
- If no other customer ID is found on the other customer, Value will be required
Thanks Guys for your help, hope can be a possible solution using data.table :