Combine two date variables colomn wise.

[Dorothy Nakiwala]

Hi there,
Dont know if anyone has faced a similar issue and can help,
When i combine two date variables with this code;
egen z = concat( date1 date2 ),format (%td)
I get a new variable, z, with points"." at the start and end of the new variable.
-------------+
| z |
|-------------|
1. | .04sep2014 |
2. | .17mar2015 |
3. | .08apr2015 |
4. | .30apr2015 |
5. | .16jun2015 |
|-------------|
6. | 18aug2015. |
7. | 25aug2015. |
8. | 02sep2015. |
9. | .08sep2015 |
10. | 01sep2015. |

The new variable can nolonger function as a date variable.
This happens even when I start by coverting the original variables to string.

Thank you

[Roger Chu]

Hello Dorothy,

I'm a bit confused at the moment with what you are asking for. First, assuming that your -egen concat()- works as it should, you still would not be able to use the new variable as a date variable. Second, I am not finding that the issue you are reporting is happening when I try something similar.

Keep in mind, I made up an example dataset. You did not provide a sample data set, so I am not sure if your issue appears specifically because of the way your data set is arranged. To provide a sample data set, use -dataex- (See http://www.statalist.org/forums/help#stata ). It is also useful to use the code delimiters when you present Stata code our output.

Regardless, I am not running into the issue you describe. Here is the code I ran.

clear
set obs 10
gen date1 = td(16mar2017)+_n
gen date2 = td(16apr2020)+_n
format date1 date2 %td

egen z = concat(date1 date2), format(%td)

And the results of the -egen- are as follows.

. list z

     +--------------------+
     |                  z |
     |--------------------|
  1. | 17mar201717apr2020 |
  2. | 18mar201718apr2020 |
  3. | 19mar201719apr2020 |
  4. | 20mar201720apr2020 |
  5. | 21mar201721apr2020 |
     |--------------------|
  6. | 22mar201722apr2020 |
  7. | 23mar201723apr2020 |
  8. | 24mar201724apr2020 |
  9. | 25mar201725apr2020 |
 10. | 26mar201726apr2020 |
     +--------------------+

I don't think that this output is what you want. "17mar201717apr2020" does not make any sense as a date variable, and it seems that you want to use z as a date variable. Could you explain what you want z to contain, and what you want to do with z? Perhaps there is a better way to get to what you want.