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Re: st: local and loops
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: local and loops
Date
Tue, 20 Aug 2013 20:21:37 +0100
Interesting. For the record, I am currently using Stata 10.1 on a
Mesolithic machine. It trims both inside and outside loops.
Nick
[email protected]
On 20 August 2013 20:17, Matthew White <[email protected]> wrote:
> Hi Nick,
>
> Thanks for your reply.
>
> There were supposed to be exactly two spaces between 1 and 2, and the
> second string specified to -strpos()- was supposed to be two
> consecutive spaces.
>
> Outside of a loop, the internal spaces in `foo' are actually preserved
> on my computer, even without the double quotes:
>
> . local foo a b c
>
> . display strpos("`foo'", " ")
> 2
>
> . display `:length local foo'
> 39
>
> If the spaces were trimmed, the length of `foo' would be 5.
>
> However, when I put this in a loop, I get different results:
>
> . forvalues i = 1/5 {
> 2. local foo a b c
> 3. }
>
> . display strpos("`foo'", " ")
> 0
>
> . display `:length local foo'
> 5
>
> When you define `foo' outside of a loop, do you get a length of 5 or 39?
>
> Inside and outside of a loop, leading and trailing spaces are trimmed
> unless double quotes are used, but as far as I can tell, internal
> spaces are typically left untrimmed.
>
> Thank you,
> Matt
>
> On Tue, Aug 20, 2013 at 3:05 PM, Nick Cox <[email protected]> wrote:
>> How many spaces are there between "1" and "2"?
>>
>> Without " " as delimiters, Stata trims internal spaces to single
>> spaces in local macro definition. The " " insist on taking things
>> quite literally.
>>
>> Try
>>
>> local foo a b c
>>
>> and see what happens.
>>
>> So, -strpos()- can't find a double space as there isn't one.
>>
>> I don't think looping is germane here.
>>
>> Nick
>> [email protected]
>>
>>
>> On 20 August 2013 19:52, Matthew White <[email protected]> wrote:
>>> Hi all,
>>>
>>> Using Stata 13 for Windows 7, I'm trying to figure out an interaction
>>> between -local- and loops. Normally when I define a local, multiple,
>>> consecutive internal spaces are preserved. For example:
>>>
>>> . local x 1 2
>>>
>>> . display strpos("`x'", " ")
>>> 2
>>>
>>> Yet when I use the same definition in a loop, the internal spaces are trimmed:
>>>
>>> . forvalues i = 1/5 {
>>> 2. local x 1 2
>>> 3. }
>>>
>>> . display strpos("`x'", " ")
>>> 0
>>>
>>> Have others experienced this before? It's probably rare that this
>>> would bite, but I'm running into such a situation now. Enclosing the
>>> contents of the local by double quotes solves the problem:
>>>
>>> . forvalues i = 1/5 {
>>> 2. local x "1 2"
>>> 3. }
>>>
>>> . display strpos("`x'", " ")
>>> 2
>>>
>>> I'm just so used to dropping these quotes when I don't need them!
>>>
>>> Thank you,
>>> Matt
>>>
>>> --
>>> Matthew White
>>> Senior Project Associate
>>> Innovations for Poverty Action
>>> 101 Whitney Avenue, New Haven, CT 06510 USA
>>> www.poverty-action.org
>>> *
>>> * 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/
>> *
>> * 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/
>
>
>
> --
> Matthew White
> Senior Project Associate
> Innovations for Poverty Action
> 101 Whitney Avenue, New Haven, CT 06510 USA
> www.poverty-action.org
> *
> * 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/
*
* For searches and help try:
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* http://www.ats.ucla.edu/stat/stata/