Convert data from DD/MM/YYYY to YYYYQQ

[Petre Ca]

I want to create a yearquarter variable from my date variable (DD/MM/YYYY)
i.e convert "28-02-2005" to "2005Q1"

[Nick Cox]

help datetime

does explain.

gen qdate = qofd(daily(yearquarter), "DMY"))
format qdate %tq

[William Lisowski]

An errant right parenthesis found its way into Nick's code.

gen qdate = qofd(daily(yearquarter, "DMY"))
format qdate %tq

[Nick Cox]

William: Thanks for the fix.

[Meghna Mahambrey]

Hi there, in the data set I'm using, interview dates are stored as 31-Oct-2004. I would like to convert them to just the year (2004). I tried the syntax "gen int_year = year(int_date)" but got the error message "type mismatch". I understand this is because the first variable is a string and the one I am trying to generate is not. Any guidance? Thank you!

[Nick Cox]

help datetime

is where to find the guidance. In your case,

. di year(daily("31-Oct-2004", "DMY"))
2004

shows the way forward, applying daily() before you apply year().

[Meghna Mahambrey]

Quick follow-up question... I'm sorry I should have articulated that 31-Oct-2004 was just an example of one observation; perhaps DD-MMM-YYYY would be a better way to communicate it, with DD being numerical, MMM being letters, and YYYY being numerical. So if I'm trying to convert from DD-MMM-YYYY (string variable name: int_date) to just YYYY (numerical variable name: int_year), would that syntax be:
di year(daily("int_date", "DMY")) int_year ?

Thanks again...

[Nick Cox]

So, apply generate instead of display and insert your variable name instead of the literal date. You showed in #5 that you understood that principle, so I didn't feel I needed to explain again.

[Sanneke van Walsem]

I have a related question to this topic. My data is displayed as 13jan1993 in Stata (storage type: int, display format: %td), however I want Stata to show the date as (YYYYMMDD). How can I do this?

[Marcos Almeida]

You may wish to try something like:

. input str30 mydate

                             mydate
  1. 13jan1993
  2. end

. gen mydate2 = daily(mydate, "DMY")

. format mydate2 %td

. list

     +-----------------------+
     |    mydate     mydate2 |
     |-----------------------|
  1. | 13jan1993   13jan1993 |
     +-----------------------+

. */ you may go on from this point

. format %tdCCYY-NN-DD mydate2

. list

     +------------------------+
     |    mydate      mydate2 |
     |------------------------|
  1. | 13jan1993   1993-01-13 |
     +------------------------+

I wouldn't format dates as a whole sequence of numbers, because it may be confusing to read, but if you wish to produce such a thing, here it goes:

. gen mydate3 = mydate2

. format %tdCCYYNNDD mydate3

. list

     +-----------------------------------+
     |    mydate      mydate2    mydate3 |
     |-----------------------------------|
  1. | 13jan1993   1993-01-13   19930113 |
     +-----------------------------------+

Hopefully that helps.