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Re: st: Looping over variables
From
Ingeborg Forthun <[email protected]>
To
[email protected]
Subject
Re: st: Looping over variables
Date
Wed, 19 Dec 2012 13:30:00 +0100
I am sorry if I have misunderstood, but the two codes do not give the
same result.
The first code:
gen n_preg = 0
forval j = 95(6)149 {
local J = `j' + 1
replace n_preg = n_preg + inlist(aa`j', 1, 5) | (inlist(aa`j', 2, 3,
4, 6, 7) & inrange(aa`J', 13, .))
}
returns:
n_preg | Freq. Percent Cum.
------------+-----------------------------------
0 | 46,703 45.91 45.91
1 | 55,024 54.09 100.00
------------+-----------------------------------
Total | 101,727 100.00
The second code:
gen n_preg = 0
forval j = 95(6)149 {
local J = `j' + 1
replace n_preg = n_preg + 1 if inlist(aa`j', 1, 5) |
(inlist(aa`j', 2, 3,
4, 6, 7) & inrange(aa`J', 13, .))
}
returns:
n_preg | Freq. Percent Cum.
------------+-----------------------------------
0 | 46,703 45.91 45.91
1 | 35,664 35.06 80.97
2 | 15,164 14.91 95.88
3 | 3,303 3.25 99.12
4 | 682 0.67 99.79
5 | 143 0.14 99.93
6 | 35 0.03 99.97
7 | 19 0.02 99.99
8 | 7 0.01 99.99
9 | 4 0.00 100.00
10 | 3 0.00 100.00
------------+-----------------------------------
Total | 101,727 100.00
This is what I need to know. I have to know the exact number of
pregnancies and not only 0 or 1.
Ingeborg
2012/12/19 Nick Cox <[email protected]>:
> This is likely to be confusing to others.
>
> As you say, you want to count the number of pregnancies and my code,
> along the lines suggested by Daniel, does that. It does that because
> the logical condition evaluates to 1 or 0, which gives you the right
> answer.
>
> In a simpler example if you are counting instances of 42 or 43 then
>
> inlist(42, 42, 43)
>
> returns 1 and
>
> inlist (24, 42, 43)
>
> returns 0 -- so in a loop you can use that result directly. You could
> say something like
>
> replace n42_43 = n42_43 + inlist(<whatever>, 42, 43)
>
> You don't have to say
>
> replace n42_43 = n42_43 + 1 if inlist(<whatever>, 42, 43)
>
> If you want to write it your way, that's fine, but there is no sense
> in which you _have_ to do that.
>
> Nick
>
> On Wed, Dec 19, 2012 at 9:56 AM, Ingeborg Forthun
> <[email protected]> wrote:
>> Thank you very much for your advice! It works! But as I want to count
>> the number of pregnancies for each observation (forgot to write this
>> in my first e-mail!) I had to add +1 in the third line in order for it
>> to add 1 for each pregnancy.
>>
>> gen n_preg = 0
>>
>> . forval j = 95(6)149 {
>> 2. local J = `j' + 1
>> 3. replace n_preg = n_preg + 1 if inlist(aa`j', 1, 5) |
>> (inlist(aa`j', 2, 3, 4, 6, 7) & inrange(aa`J', 13, .))
>> 4. }
>>
>>
>> Ingeborg
>>
>>
>> 2012/12/18 Nick Cox <[email protected]>
>>>
>>> I agree with Daniel's main advice. You can simplify this (e.g.)
>>>
>>> gen n_preg = 0
>>> forval j = 95(6)149 {
>>> local J = `j' + 1
>>> replace n_preg = n_preg + inlist(aa`j', 1, 5) | (inlist(aa`j', 2, 3,
>>> 4, 6, 7) & inrange(aa`J', 13, .))
>>> }
>>>
>>> See also for specific and general advice:
>>>
>>> [D] functions . . . . . . . . . . . . . . . inlist() programming function
>>> (help inlist())
>>>
>>> [D] functions . . . . . . . . . . . . . . . inrange() programming function
>>> (help inrange())
>>>
>>> SJ-9-1 pr0046 . . . . . . . . . . . . . . . . . . . Speaking Stata: Rowwise
>>> (help rowsort, rowranks if installed) . . . . . . . . . . . N. J. Cox
>>> Q1/09 SJ 9(1):137--157
>>> shows how to exploit functions, egen functions, and Mata
>>> for working rowwise; rowsort and rowranks are introduced
>>>
>>> SJ-6-4 dm0026 . . . . . . Stata tip 39: In a list or out? In a range or out?
>>> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
>>> Q4/06 SJ 6(4):593--595 (no commands)
>>> tip for use of inlist() and inrange()
>>>
>>> It seems also that the names of your variables bear little relation to
>>> their contents. Systematic use of -rename- is likely to make further
>>> analysis much easier (and less error-prone).
>>>
>>> Finally, for "STATA" read "Stata", and please read the Statalist FAQ
>>> to see why.
>>>
>>> Nick
>>>
>>> On Tue, Dec 18, 2012 at 8:47 AM, daniel klein <[email protected]> wrote:
>>>
>>> > You could probably create a loop over the values 95, 101 and so on,
>>> > and add 1 to the respective number inside the loop to get at the
>>> > durration. But I would look at -egen-'s -anycount()- function first.
>>> > This might be a good way of approching this.
>>>
>>> Ingeborg Forthun
>>>
>>> > [...]
>>> > I want to make a variable that counts the number of pregnancies for each
>>> > woman if outcome is 1 or 5 or if outcome is 2,3,4,6 or 7 and number of
>>> > weeks of pregnancy was more than 12 weeks. Number of weeks of
>>> > pregnancy is given by aa96 (corresponding to the outcome of the first
>>> > pregnancy given by aa95), aa102 (corresponding to the outcome of the
>>> > second pregnancy given by aa101), and so on.
> *
> * 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/
*
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