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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Mata Data Structure or "variable" variable names for timeseries computations |

Date |
Wed, 1 Aug 2012 10:00:22 -0500 |

Tirthankar gave a detailed reply with lots of good-looking code. On the detail that Mata [sic] does not have macros in the same way as Stata, see SJ-11-2 pr0052 . . . . Stata tip 100: Mata and the case of the missing macros . . . . . . . . . . . . . . . . . . . . . . . . W. Gould and N. J. Cox Q2/11 SJ 11(2):323--324 (no commands) tip showing how to do the equivalent of Stata's macro substitution in Mata Nick On Tue, Jul 31, 2012 at 11:49 PM, Matthew McKay <matthew.mckay@anu.edu.au> wrote: > I am trying to compute differences in sets of matrices matrices using MATA > for a time series 1995 to 2010. > I am producing a mata function to compute the differences for each year > after I load in ALL my yearly data matrices. > My Issue is in Step#2 is that I want to use a similar methodology to local > macro's in do files. (which can't be done) > > How can I pass part of a variable name (like Year) into the function and > then perform a set of computations over the data that is loaded in MATA? > In MATA how can you cycle through different variables (substituting in > different year append) and compute a new set of matrices? > Should I be constructing a Struct that contains a Data Matrix and Time > Series Indicator? > > I understand the MATA function is compiled and therefore local macro > substitution can't be done ... but was wondering if anyone else has an > elegant solution to reference different variables in MATA by changing a > component of the variablename (knowing the variable is defined in memory). > > Many Thanks, > Matthew > > Step #1: > ** > ** Import ALL MCP Matrix > ** > local Years = "1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 > 2007 2008 2009 2010" > clear all > local END = "end" > foreach year of local Years { > use [file_`year'.dta], clear // Load MCP Matrices into > Mata Memory // > drop ReporterISO3C > mata > Mcp_`year' = st_data(., .) > `END' > } > > Step#2: > ** MATA FUNCTION ** > > clear all > mata > void calcdiffvectors(real scalar StartYear, real scalar EndYear) { > for(year = StartYear; year < EndYear; year++) { > !!!!!!!!! local NextYear = `year' + 1 !!!!!!!!!!!!! > !!!!!!!!! Mcp_`year'_`NextYear' = Mcp_`year' :- Mcp_`NextYear' > !!!!!!!!!! > } > } > end > > Step #3: > mata: calcdiffvectors(1995, 2010) > // I can then retrieve the difference vectors using get mata etc. // > > * * 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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