Conditional adding certain data column from two data file

Question

I have a question on conditional adding certain column from two data files. For instance, I have this data file:

Data 1

ID  purchased
1   5
2   3
3   3
4   3
5   3
6   4
7   4
8   4
9   4
10  4

Data 2

ID  Date3   Date4   Date5
1   2014    2013    2017
2   2014    2015    2012
3   2013    2016    2014
4   2015    2017    2014
5   2016    2012    2017
6   2017    2013    2017
7   2012    2013    2012
8   2014    2013    2014
9   2014    2015    2014
10  2015    2016    2015

So in the two files, the number on the purchase column (data 1) link to a specific date. For example, ID 1 purchased 5 (data 1) should link to ID 1 Date5 (data 2); ID 2 purchased 3 links to ID 2 Date3 (data 2), etc. So the results looks like below.

Result:

ID  purchased Date
1   5       2017
2   3       2014
3   3       2013
4   3       2015
5   3       2016
6   4       2013
7   4       2013
8   5       2014
9   5       2014
10  4       2016

I was thinking of using couple if statements like below:

if ((Data1$ID== Data2$ID) & Data1$purchased ==3) {
  Data1$Date<- Data2$Date3  
} 

and do the same for purchased 4 and 5... I think i have the wrong approach and appreciate any help! I hope this makes sense. Thank you in advance.

Answer 1

Maybe there is a more beautiful way but you can do like this:

Data1$Date <- ifelse(Data1$purchased==3,Data2$Date3,ifelse(Data1$purchased==4,Data2$Date4,Data2$Date5))

The condition is that your ID are sorted so you don't need to insert the condition on ID in the ifelse statement.