[R] If cycle takes to much time...

[marcoguerzoni]

dear all,

thank you for reading. 

I have a dataset of artists and where and when they had an exhibition.
I'd like to create an affiliation network in the form of matrix, telling me 
which aritist have been in the same at the same time.
I manage to do it, but given that I have 96000 observation the program takes 
30 months to complete.
her what i have done.
the data look like this

Artist <-c(1,2,3,2,4,4,5)
Begin <- as.Date(c('2006-08-23', '2006-03-21', '2006-03-06', '2006-01-13',
'2006-05-20', '2006-07-13', '2006-07-20')) 
End <- as.Date(c('2006-10-23', '2006-11-30', '2006-05-06', '2006-12-13',
'2006-09-20', '2006-08-13', '2006-09-20')) 
Istitution <- c(1, 2, 2, 1, 1, 2, 1)

artist is the name of the artist, Begin and End is the when and Istitutionis
the where.

my IF is working, 


#number of unique artist
c <- unique(Artist)
d <- length(c)
a <-length(Artist)

B <- mat.or.vec(d,d)

for(i in 1:d) {
for(j in 1:d) {
if (Istitution[i]  == Istitution[j]) {


if (Begin[i] <= End[j])
{
if (End[i]-Begin[j] >= 0) {
B[i,j] <- B[i,j]+1
B[i,i] <- 0

}


}
else{
if (End[j]-Begin[i] >= 0) {
B[i,j] <- B[i,j]+1
B[i,i] <- 0


}
 }
  }
   }
print(i)
    }


do you have a way to make the programm simpler and faster?

thank you very much

Marco Guerzoni,
Department of Economics
University of Turin






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