Bookmark and Share

Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: st: generate variable versus define scalar, with conditional statement


From   annoporci <annoporci@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: generate variable versus define scalar, with conditional statement
Date   Wed, 16 Jan 2013 20:35:57 +0800

Or, he can check if each date occurs at most once,
and simplify his code.
	bys date : assert _n == 1
	summ  open if date == mdy(1,2,2001), meanonly
	scalar newscalar = r(mean)

In the present case, date is a unique identifier, but this is a great addition to my toolkit:

bys date : assert _n == 1

Thanks Paul, I appreciate your feedback very much,

Patrick

---
Patrick Toche.



On Wed, 16 Jan 2013 19:44:55 +0800, Seed, Paul <paul.seed@kcl.ac.uk> wrote:

Dear Statalist,

It appears that what Patrick Toche wants is not something that
Stata can do in a single command.  This is because what he wants
is not completely clear.

He wants for the system dataset -sp500- to produce a scalar that gives
the value of a particular variable (-open-) at a particular date
chosen by him (-date-).

Depending on the data set , this is an ambiguous request. Suppose the date in question occurs more than once, with different values of -open- attached.
[It doesn't in this case, but it could easily do].
Does he want the minimum, the maximum, the average, or a missing value?

The following covers all these options.

	clear all
	sysuse sp500

	summ  open if date == mdy(1,2,2001), meanonly
/// the meanonly option suppresses output, and saves computer time
///by not calculating the standard deviation.  It is not essential.
	scalar newscalar_mean = r(mean)
	scalar newscalar_min= r(min)
	scalar newscalar_max= r(max)
	if r(n) == 1 scalar newscalar = r(mean)

Or, he can check if each date occurs at most once,
and simplify his code.
	bys date : assert _n == 1
	summ  open if date == mdy(1,2,2001), meanonly
	scalar newscalar = r(mean)

BW

Paul T Seed, Senior Lecturer in Medical Statistics,
Division of Women's Health, King's College London
Women's Health Academic Centre, King's Health Partners
(+44) (0) 20 7188 3642.



*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/


--
Patrick Toche.
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   Site index