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Re: st: regexm


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: regexm
Date   Sat, 27 Aug 2011 14:59:57 +0100

Better in what sense? Quicker to get a solution? Simpler? Other criteria?

I don't know a way of counting more than 9 matches directly. I think
you would need, if you continue to follow that path, to loop over a
string repeatedly finding new instances and counting.

See also -moss- from SSC.

Nick

On Sat, Aug 27, 2011 at 2:52 PM, KOTa <kota.alba@gmail.com> wrote:
> yes, i do work now with split, just thought with regex it will be better.
>
> anyway, is there a way to find out how many expressions regexm finds?
> 1. what i mean is i can access the 1st 2nd etc up to 9 with regexs,
> but if i dont know how many there are -> i dont know which one is
> last.
> 2. what if more the 9 expressions found? according to manual regexs
> only can have 0-9 parameters.
>
>
> thanks
>
> 2011/8/27 Nick Cox <njcoxstata@gmail.com>:
>> Well, you did say "it always ends by "% th_aft".
>>
>> I will continue as I started.
>>
>> If you first blank out stuff you don't need then you can just use
>> -split- to separate out elements. If you parse on spaces then it is
>> immaterial when you have 2 or 3 digits before, you retrieve the number
>> either way.
>>
>> No need for regex demonstrated.
>>
>> Nick
>>
>> On Sat, Aug 27, 2011 at 2:16 PM, KOTa <kota.alba@gmail.com> wrote:
>>> thanks Eric, Nick I used your advices and almost finished.
>>>
>>> but encountered one small problems on the way.
>>>
>>> i have the same type of string -  "0.15%-$1(B) 0.14%-$2(B) 0.12%-$2(B)
>>> 0.10% th_aft." - number of digits after the dot can be 2 or 3, it's
>>> not constant
>>>
>>> and i am trying to extract the last % (i.e.0.10% in this case) using
>>> "$" like this:
>>>
>>> g example = regexs(0) if regexm( fee_str, "[0-9]+\.[0-9]*[%]$") or g
>>> example = regexs(0) if regexm( fee_str, "[0-9]+\.[0-9]*[%]+$") and it
>>> fails in both cases.
>>>
>>> the result is empty
>>>
>>> it does extract the first one (0.15%) if i dont use "$"
>>>
>>> what is wrong?
>>>
>>> thanks
>>>
>>> p.s. Nick, th_aft is not a terminator, its not always there
>>>
>>>
>>> 2011/8/27 Nick Cox <njcoxstata@gmail.com>:
>>>> It is not obvious to me that you need -regexm()- at all.
>>>>
>>>> The text " th_aft" appears to be just a terminator that you don't care
>>>> about, so remove it.
>>>>
>>>> replace j = subinstr(j, " th_aft", "", .)
>>>>
>>>> The last element can be separated off and then removed.
>>>>
>>>> gen last = word(j, -1)
>>>>
>>>> replace j = reverse(j)
>>>> replace j = subinstr(j, word(j,1) , "", 1)
>>>> replace j = reverse(j)
>>>>
>>>> We reverse it in order to avoid removing any identical substring.
>>>>
>>>> Those three lines could be telescoped into one.
>>>>
>>>> Then it looks like an exercise in -subinstr()- and -split-.
>>>>
>>>> Nick
>>>>
>>>> On Sat, Aug 27, 2011 at 2:28 AM, Eric Booth <ebooth@ppri.tamu.edu> wrote:
>>>>> <>
>>>>>
>>>>> Here's an example...note that I messed with the formatting of the %'s and $'s in my example data a bit to show how flexible the -regex- is in the latter part of the code; however, you'll need to check that there aren't other patterns/symbols in your string that could break my code.
>>>>>  There are other ways to approach this, but I think the logic here is easy to follow:
>>>>>
>>>>> *************! watch for wrapping:
>>>>>
>>>>> **example data:
>>>>> clear
>>>>> inp str70(j)
>>>>> "A: 0.35%-$197(M) 0.30%-$397(M) 0.27% th_aft."
>>>>> "A: 0.25%-$198(M) 0.12%-$398(M)  0.99%-$300(M) 0.00% th_aft."
>>>>> "A: 1.0%-$109(M) 0.1% th_aft."
>>>>> "A: 0%-$199(M) 0.30%-$366(M) 1.99% th_aft."
>>>>> end
>>>>>
>>>>>
>>>>>
>>>>> **regexm example == easier to use -split- initially
>>>>> g example = regexs(0) ///
>>>>>  if regexm(j, "(([0-9]+\.[0-9]*[%-]+)([\$][0-9]*))")
>>>>> l
>>>>> drop example
>>>>>
>>>>>
>>>>> **split:
>>>>> replace j = subinstr(j, "A: ", "", 1)
>>>>> split j, p("(M) ")
>>>>>
>>>>> **first, find x10 :
>>>>> g x10 = ""
>>>>>
>>>>> tempvar flag
>>>>> g `flag' = ""
>>>>> foreach var of varlist j? {
>>>>> replace `flag' = "`var'" if ///
>>>>>        strpos(`var', "th_aft")>0
>>>>> replace x10  = subinstr(`var', "th_aft.", "", .) ///
>>>>>         if `flag' == "`var'"
>>>>> replace `var' = "" if strpos(`var', "th_aft")>0
>>>>>        }
>>>>>
>>>>>
>>>>> **now, create x1-x9 and y1-y9
>>>>> forval num = 1/9 {
>>>>>  g x`num' = ""
>>>>>  g y`num' = ""
>>>>>  cap replace x`num' = regexs(0) if ///
>>>>>        regexm(j`num', "([0-9]+\.?[0-9]*[%]+)") ///
>>>>>        & !mi(j`num') & mi(x`num') //probably overkill
>>>>>  cap replace y`num' = regexs(0) if ///
>>>>>        regexm(j`num', "([\$][0-9]*\.?[0-9]*)") ///
>>>>>        & !mi(j`num') & mi(y`num')
>>>>>        }
>>>>> **finally, create y10 == y2:
>>>>>  g y10 = y2
>>>>>
>>>>>
>>>>> ****list:
>>>>> l *1
>>>>> l *2
>>>>> l *3
>>>>>
>>>>> *************!
>>>>> - Eric
>>>>>
>>>>> On Aug 26, 2011, at 6:59 PM, KOTa wrote:
>>>>
>>>>>> I am trying to extract some data from text variable and being new to
>>>>>> stata programming struggling with finding right format.
>>>>>>
>>>>>> my problem is as following:
>>>>>>
>>>>>> for example i have string variable as following: "A: 0.35%-$100(M)
>>>>>> 0.30%-$300(M) 0.27% th_aft."
>>>>>>
>>>>>> number of pairs "% - (M)" can be from 1 to 9 and it always ends by "% th_aft"
>>>>>>
>>>>>> I have 10 pairs of variables X1 Y1 .... X10 Y10
>>>>>>
>>>>>> my goal is to extract all pairs from the string variable and split
>>>>>> them into my separate variables.
>>>>>>
>>>>>> in this case the result should be:
>>>>>>
>>>>>> X1  = 0.35%
>>>>>> Y1 = $100
>>>>>>
>>>>>> X2 = 0.30%
>>>>>> Y2 = $300
>>>>>>
>>>>>> X3-X9 = y3-Y9 = 0
>>>>>>
>>>>>> X10 = 0.27%
>>>>>> Y10 = Y2 (i.e. last Y extracted from sting)
>>>>>>
>>>>>> I am trying to use regexm but unsuccessfully, Any suggestions?
>>>>>>
>>>>
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>>>
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