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Tony,
I'm not sure how efficient it is, but here is a way of passing a matrix/dataframe. First, you create a list in Splus with as many elements as no. of columns in your dataframe/matrix. Then you read back the list in C by first getting the length of the list, which tells you the no. of pointers you need, then read off the size of the first vector in the list to get the no. of rows.
Hope this helps.
Horace W. Tso
PGE
Portland, Oregon
=======================================================
s_object *ReadDF(s_object *sDF ) {
S_EVALUATOR
s_object **sLptr;
s_object *sL;
double **cData;
long i=0, j=0, n=0, n_col=0, n_row=0;
//Cast input and find length of the list
sLptr = LIST_POINTER(sDF);
n_col = GET_LENGTH(sDF);
// Just get the row number from the first column of the list
n_row = GET_LENGTH(sLptr[0]);
// Allocate with Salloc (for some reason S_alloc gives type cast error)
cData = Salloc(n_col, double*);
for(i=0; i < n_col; i++) {
cData[i] = NUMERIC_POINTER(sLptr[i]);
}
// Now you have your matrix......
}
======================================================
>>> Tony Smith <quickcur@yahoo.com> 12/13/05 2:48 PM >>>
I was trying to call c++ function from splus. My goal is to pass a two dimensional array to c++ code, do some computation and return. But I am sure how to pass two dimensional array to splus. The example shown bellow is for one dimensional data. I do not want to use CSPmatrix class since it will be slower to access the data in c++. c++ void spC(double* pdX, double* pdY, long* plLen) { S_EVALUATOR // TODO: Replace the example code below with your own code. //Validate the input arguments if((pdX == NULL) || (pdY == NULL) || plLen == NULL) PROBLEM "Invalid input" ERROR; //Perform element by element operation for(long n=0; n< *plLen; n++) pdY[n] = pdX[n][n] * pdX[n][n]; //The output = the input squared return; } splus "spC" <- ## TODO: Help documentation function(x) { ## TODO: Modify the codes below ## Example of .C() with two arguments ## See sp.cxx for the C/C++ (VC++) implementation of spC() len = length(x) y = .C("spC", as.double(x), y=double(len), len )$y y __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -------------------------------------------------------------------- This message was distributed by s-news@lists.biostat.wustl.edu. To unsubscribe send e-mail to s-news-request@lists.biostat.wustl.edu with the BODY of the message: unsubscribe s-news |