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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu, "Pablo.CARVALLO" <pablocepal@gmail.com> |

Subject |
Re: st: How to identify two consequtives values of a variable |

Date |
Fri, 22 Jul 2011 17:27:48 -0500 |

Pablo replied directly to me. Please note the request to close threads publicly. I started writing if abs(x[_n-1]) == 1 as a way of catching both 1 and -1 and realised that the "== 1" was not needed. What you have is equivalent for your data. Nick On Fri, Jul 22, 2011 at 5:16 PM, Pablo.CARVALLO <pablocepal@gmail.com> wrote: > Thanks Nick, I didn't understand your first instruction, but I tried > with a little modified version of your routine, and it works properly: > > gen previous=x[_n-1] if x[_n-1]!=0 > replace previous=previous[_n-1] if missing(previous) > gen y1= previous==x > > Regards, > > Pablo > > > . gen previous = x[_n-1] if abs(x[_n-1]) > . replace previous = previous[_n-1] if missing(previous) > . gen y = x == 1 & previous ==1 > > > Nick > > On Fri, Jul 22, 2011 at 12:06 PM, Pablo.CARVALLO <pablocepal@gmail.com> wrote: >> Hi Statalist, >> >> I create a variable x which states a local max (1), a local min(-1), >> and 0 in other case. If x==1, the following value may be 0 or -1, but >> it cannot be 1 again. For example, an 'ideal' x may be: >> >> x >> -- >> 0 >> 0 >> 1 >> 0 >> 0 >> 0 >> 0 >> -1 >> 0 >> 0 >> 1 >> -1 >> 0 >> 0 >> 0 >> 1 >> >> But I have something like this: >> >> x >> -- >> 0 >> 0 >> 1 >> 0 >> 0 >> 0 >> 0 >> 1 ----> this value is wrong, because previous x different from 0 was 1. >> 0 >> 0 >> -1 >> 1 >> 0 >> 0 >> 0 >> -1 >> >> I need a variable 'y' which tells me when x takes this wrong values: >> >> x y >> --------- >> 0 0 >> 0 0 >> 1 0 >> 0 0 >> 0 0 >> 0 0 >> 0 0 >> 1 1 ---> y==1 >> 0 0 >> 0 0 >> -1 0 >> 1 0 >> 0 0 >> 0 0 >> 0 0 >> -1 0 >> > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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