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From |
Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Making a Matrix from Three Variables |

Date |
Sat, 9 May 2009 22:38:13 +0100 |

<> <> 1) Amadou's solution can be streamlined considerably by replacing the first part as in the code included below. 2) The line: tomata x y z, missing does not work because -missing- is not a valid option for -tomata- (Gould, SSC). 3) Allan's solution is efficient, but you might want to watch out for missing values in your original data. So, a slight modification is included below. /*** Begin ***/ /* Simulate some data */ clear clear mata set obs 100 // create a 20x5 matrix egen cols = seq(), from(1) to(5) sort cols egen rows = seq(), from(1) to(20) gen var3 = runiform() /* Mata solution - I - not flexible */ sort cols rows /* note sort order */ qui su rows scalar define sMvrows = r(max) qui su cols scalar define sMvcols = r(max) mata: vA = st_data(.,"var3") mB = colshape(vA,st_numscalar("sMvrows"))' mB end /* Mata solution - II - Allan's solution modified */ mata: real matrix sparse(real matrix x) { real matrix y real scalar k y = J(colmax(x[,1]),colmax(x[,2]),.) for (k=1; k<=rows(x); k++) { y[x[k,1],x[k,2]] = x[k,3] } return(y) } mC = st_data(.,("rows", "cols", "var3")) mD = sparse(mC) mD /* Check the two solutions are equivalent */ asserteq(mD, mB) end /*** End ***/ On Sat, May 9, 2009 at 7:13 PM, Amadou DIALLO <stata.diallo@gmail.com> wrote: > Hi Allan, > > This is my 3 cents solution (have not get the time to put it in a > formal mata programm, just tested on the command line). I hope it can > lead you to what you need to achieve if you play around a bit with it. > > Best regards. > > Amadou. > > > clear > > // suppose you have 3 variables x, y, z, with number of observations > of x+y = number of observations of z > > set obs 10 > > g x=. > replace x=1 in 1 > replace x=2 in 2 > > g y=. > replace y =1 in 1 > replace y =2 in 2 > replace y =3 in 3 > replace y =4 in 4 > replace y =5 in 5 > > //g z = round(uniform(),1) > > g z=. > replace z =1 in 1 > replace z =2 in 2 > replace z =3 in 3 > replace z =4 in 4 > replace z =5 in 5 > replace z =6 in 6 > replace z =7 in 7 > replace z =8 in 8 > replace z =9 in 9 > replace z =10 in 10 > > // tomata x y z, missing // Don't know why not working > tomata x in 1/2 > tomata y in 1/5 > tomata z > > mata: > > c = rows(x) > d = cols(y') > M=J(c,d,.) > for(i=1;i<=d;i++) { > M[1,i] = z[i] > k=d+i > M[c,i] = z[k] > } > M > z > end > > > > 2009/5/9, Glenn Goldsmith <glenn.goldsmith@gmail.com>: >> Hi Allan, >> >> It seems like what you're after is more-or-less the same as converting from >> sparse matrix storage, so the mata code here should do the trick: >> >> http://www.stata.com/statalist/archive/2009-04/msg00142.html >> >> You just need to get your variables into a mata matrix to start with and you >> should be away: >> >> mata : st_view(x=.,.,("var2","var1","var3")) >> >> NB: Note the inverted order of var1 and var2. This is because the code for >> -sparse()- assumes that the first variable provides the row index, and the >> second variable provides the column index. >> >> HTH, >> >> Glenn. >> >> Allan Joseph Medwick <amedwick@gmail.com> wrote: >> >> Hi, All, >> >> I have three variables (var1, var2, var3). I would like to create a >> matrix where the values of var1 are the columns (ascending), the >> values of var2 are the rows (also ascending), and the values of var3 >> are the elements in the matrix. I know there must be a user defined >> procedure out there to do this, but I haven't been able to find it. >> >> Thanks, >> Allan >> >> >> * >> * 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/ >> > > > -- > --- > > Amadou B. DIALLO, PHD > Development Economist > Director, Center for Research and Training on Adult Education > Mayotte, FRANCE > www.aprosasoma.org > +262639693250 > * > * 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/ > -- To every ω-consistent recursive class κ of formulae there correspond recursive class signs r, such that neither v Gen r nor Neg(v Gen r) belongs to Flg(κ) (where v is the free variable of r). * * 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: Making a Matrix from Three Variables***From:*Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com>

**References**:**st: Making a Matrix from Three Variables***From:*"Glenn Goldsmith" <glenn.goldsmith@gmail.com>

**Re: st: Making a Matrix from Three Variables***From:*Amadou DIALLO <stata.diallo@gmail.com>

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