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From |
"Gabi Huiber" <ghuiber@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: R Array [was: Mata for data management] |

Date |
Fri, 1 Feb 2008 10:59:36 -0500 |

I can't think of any example, but up until last year I have been using only Stata for all my data analysis needs, so I am biased. I can only speculate that arrays accommodate a style of programming that's more mainstream. I base this on a very brief tinkering experience. Last summer I picked up R and PHP. Then I took an online class on C++ through my local community college. I didn't know much about computer programming, so I didn't know what to expect, but I found all kinds of common traits between these languages and they all had arrays; so I just figured that arrays must be a general language construct because R, PHP and C++ are not designed to do the same thing. So, once I got to use arrays I liked them. If Stata offered them I could use them here too, but I don't really miss them, if that's what you're getting at. I have been using Stata for so long that its ways feel natural to me. Gabi On Feb 1, 2008 10:02 AM, Scott Merryman <scott.merryman@gmail.com> wrote: > Thanks. > > I guess, more concretely, what can be done (or preformed more > efficiently) with an R array that cannot be done with Stata (-foreach- > or -forv-)? > > Scott > > > On Jan 31, 2008 9:44 PM, Gabi Huiber <ghuiber@gmail.com> wrote: > > Oops. Thank you, Scott. > > > > An array is a general data object. It's a a vector when indexed by one > > subscript, a matrix when indexed by two subscripts, or it can be > > indexed by more than two subscripts. It can take numeric and character > > elements. You can think of a numeric array A(i,j,k) as a list of i > > matrices of (j,k) size. The ability to take non-numeric elements is > > useless in statistics, but it's helpful in general data management. > > > > In Stata or SAS we think of data sets as tables with as many columns > > as variables and as many rows as the largest number of non-missing > > observations. This works for statistical analysis. General-purpose > > programming languages (judging by the two I dabble in) seem to want > > you to think of your data in terms of data objects -- scalars, > > vectors, matrices, lists, etc. R is a statistical analysis programming > > environment, but it stayed close to this general-purpose way of > > dealing with data; maybe because its underlying language, S, was > > invented by a computer scientist? > > > > Gabi > > > > > > On Jan 31, 2008 10:14 PM, Scott Merryman <scott.merryman@gmail.com> wrote: > > > On Jan 31, 2008 8:48 PM, Gabi Huiber <ghuiber@gmail.com> wrote: > > > > I'm trying to cheat and speed things up a bit when dealing with a > > > > bunch of files with names such as fileYYYYMMDD.dta. I could collect > > > > the numeric part of the names in a column vector that starts with the > > > > initial values a=J({potential number of files}, 1,0). But there is a > > > > fair chance that my YYYYMMDD succession has gaps, so at the end of the > > > > process this column vector will have some zeroes. > > > > > > > > I would like to do this: > > > > > > > > mata > > > > a=sort(a,1) > > > > > > > > Then drop all the zero elements of a, and end up with a shorter > > > > vector. But I can't find anything like "drop rows" in the Mata book or > > > > Google. Any ideas? > > > > > > -select()- ? > > > > > > mata > > > A = (1,2,3,4,0,5,6,0,0,7) > > > A2 = select(A, A:>0) > > > A2 > > > end > > > > > > > > > > Generally, some R-like way to deal with arrays would be nice to have > > > > in Mata or Stata. > > > > > > How do R arrays work? > > > > > > Scott > > > > > > > > * > > > * For searches and help try: > > > * http://www.stata.com/support/faqs/res/findit.html > > > * http://www.stata.com/support/statalist/faq > > > * http://www.ats.ucla.edu/stat/stata/ > > > > > * > > * For searches and help try: > > * http://www.stata.com/support/faqs/res/findit.html > > * http://www.stata.com/support/statalist/faq > > * http://www.ats.ucla.edu/stat/stata/ > > > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: R Array [was: Mata for data management]***From:*"Scott Merryman" <scott.merryman@gmail.com>

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