Re: Re: st: Problem with datetime functions

[George Vega Yon <g.vegayon@gmail.com>]

Dear Nick,

Thank you for your answer. Good tip on using double when working with
dates and times, though, at least to me, it does make sense that stata
warns you (or something) in this type of operations. For most of the
people who I know that uses stata, data type distinction (float, long
or double) isn't straightforward.

I need to generate a new variable because, I merge this dataset with
another one which has a "date" variable as integer (and not as stata
date-time "data type"). Even when I prefer working with calendar
variables, almost all of the data sets in my work work with YYYYMMDD
integer format.

Best regards!,

George Vega Yon
7 647 2552
http://cl.linkedin.com/in/georgevegayon

2013/6/11 Nick Cox <njcoxstata@gmail.com>:

It's not a bug in Stata. It's yours.

On your -generate- you need a data type other than -float- to hold
every digit exactly. -long- should work, but whenever dates and times
are mentioned, thinking -double- is safe.

-tostring, force- shows that you knowingly run risks of damaging the data.

But why -generate- a new variable? Use the display format  %tdCYND

clonevar myday2 = myday
format myday2 %tdCYND

is a better way to proceed if you really need a new variable.

Nick
njcoxstata@gmail.com


On 11 June 2013 15:18, George Vega Yon <g.vegayon@gmail.com> wrote:
> Dear list members,
>
> I'm facing a problem while generating an integer from day-time
> variable. In short, what I (in stata %td format) have is
>
> myday
> 01jan2002
> 02jan2002
> 03jan2002
> 04jan2002
> ...
>
> What I want is
>
> myday2
> 20020101
> 20020102
> 20020103
> 20020104
> ...
>
> Which is I though I could generate by:
>
> gen myday2 = year(myday)*10000 + month(myday)*100 + day(myday)
>
> But acctually returns
>
> myday2
> 20020100
> 20020102
> 20020104
> 20020104
>
> So, it seems that stata is rounding my new variable. I don't want to
> say that this is a bug, but what are the alternatives?.
>
> I've solve this with:
>
> format %tdCCYYNNDD myday
> tostring myday, u gen(myday2) force
> destring myday2, replace
>
> myday2
> 20020101
> 20020102
> 20020103
> 20020104
>
> But still, stata rounding my integers doesn't sound very good. Any ideas?
>
> Thanks!
>
> George Vega
>
> PS: Running on windows 7
> c(stata_version) = 12.1
> c(version) = 12.1
> c(born_date) = "18 Dec 2012"
> c(flavor) = "IC"
> c(os) = "Windows"
> c(osdtl) = "64-bit"
> c(machine_type) = "PC (64-bit x86-64)"
> c(byteorder) = "lohi"
>
>
>
> George Vega Yon
> 7 647 2552
> http://cl.linkedin.com/in/georgevegayon
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