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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: mata for-if-else |

Date |
Wed, 14 Apr 2010 12:04:36 +0100 |

Sorry: you didn't make the second mistake here! Nick n.j.cox@durham.ac.uk -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox Sent: 14 April 2010 11:45 To: statalist@hsphsun2.harvard.edu Subject: RE: st: mata for-if-else There are several mistakes here. The syntax of -for- requires semi-colons. Testing for equality requires == not =. Mata has no equivalent of Stata's -if- qualifier. Positively, this codes more congenially using ?: Try for(i=1; i<1001; i++) { a[i] = b[i] == 1 ? 2 : 3 } Nick n.j.cox@durham.ac.uk Abhimanyu Arora Thanks Sabrina, but unfortunately the problem persists. If I understood correctly what you meant, I used the following: mata a=J(1000,1,1) for(i=1,i<1001,i++) { a[i]=2 if b[i]==1 a[i]=3 if b[i]!=1 } a end Sabrina Carrossa I am not sure, but I guess you'd better use the "if qualifier" instead of the "if-else" command. On 14 April 2010 10:54, Abhimanyu Arora > I have simplified my problem to a large extent, but essentially has to do > with using for-if-else commands in mata. I would like to create a matrix 'a' > whose values depend on an existing matrix 'b' (both are 1000X1 vectors to be > precise). I need to tell mata the dimension of a first. But all I get after > executing the commands below is the original vector 'a'. What could be the > possible error? I have tried adding and removing braces but it is not > working... > > > > > a=J(1000,1,.) > for(i=1,i<1001,i++) { > if (b[i]==1){ > a[i]=2 > } > else {a[i]=3 > } > } > a > end > * * 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/ * * 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/

**Follow-Ups**:**RE: st: mata for-if-else***From:*"Abhimanyu Arora" <abhimanyu.arora@student.kuleuven.be>

**References**:**Re: st: mata for-if-else***From:*Sabrina Carrossa <carrossa@gmail.com>

**RE: st: mata for-if-else***From:*"Abhimanyu Arora" <abhimanyu.arora@student.kuleuven.be>

**RE: st: mata for-if-else***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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