Douglas Bates <[EMAIL PROTECTED]> writes: > "wolski" <[EMAIL PROTECTED]> writes: > > > I want to return a matrix. The code does the R interfacing. This > > version does it fine. > > > > SEXP ans,dim; > > PROTECT(ans = NEW_NUMERIC(count*2)); > > memcpy(NUMERIC_POINTER(ans),result,count*sizeof(double)); > > memcpy(&(NUMERIC_POINTER(ans)[count]),occur,count*sizeof(double)); > > /** PROTECT(dim=NEW_INTEGER(2)); > > INTEGER_POINTER(dim)[0]=2; > > INTEGER_POINTER(dim)[1]=count; > > setAttrib(ans,R_DimSymbol,dim); > > */ > > UNPROTECT(7); > > > > If I uncomment the lines 5 to 8 than all is working fine four small > > count's (tested 10,20). But if the result is an array with about > > 2000 entries R crashes vicious and violently with the lax comment > > > > Process R trace trap at Wed Feb 11 13:55:45 2004 > > > > Anyone is seeiing something what I can not see? > > In most cases it is easier to use allocMatrix instead of assigning a > dimension attribute to a numeric vector. You could write this as > > SEXP ans = PROTECT(allocMatrix(REALSXP, 2, count)); > memcpy(NUMERIC_POINTER(ans),result,count*sizeof(double)); > memcpy(&(NUMERIC_POINTER(ans)[count]),occur,count*sizeof(double)); > UNPROTECT(1); > > Another enhancement is use Memcpy, as in > > SEXP ans = PROTECT(allocMatrix(REALSXP, 2, count)); > double *ansp = REAL(ans); /* same as NUMERIC_POINTER(ans) */ > > Memcpy(ansp, result, count); > Memcpy(ansp + count, occur, count); > UNPROTECT(1); > > Regarding your particular problem, did you happen to change the > argument to UNPROTECT when you changed the code? You may be getting a > stack imbalance if you change the number of PROTECTs that are executed > and don't change the UNPROTECT count. > > This is why I generally try to write C functions with only one PROTECT > in then. Because PROTECTing an object also PROTECTs all components > reachable from that object I allocate other storage as components of > the (PROTECT'ed) result then manipulate those components. For > example, if I don't use allocMatrix I would write what you did as > > SEXP ans = PROTECT(NEW_NUMERIC(count * 2)); > double *ansp = NUMERIC_POINTER(ans); > int *dims; > > Memcpy(ansp, result, count); > Memcpy(ansp + count, occur, count); > setAttrib(ans, R_DimSymbol, NEW_INTEGER(2)); > dims = INTEGER_POINTER(getAttrib(ans, R_DimSymbol)); > dims[0] = 2; > dims[1] = count; > UNPROTECT(1);
By the way, you probably have the dimensions backwards here. Recall that R stores matrices in column-major ordering so you probably want the dimensions to be (count, 2) not (2, count). ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
