drop independent vars with zero variance after transformation

daroczig · Aug 28, 2014 · 70c024f · 70c024f
1 parent a4ec71c
commit 70c024f
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/R/basic-models.R b/R/basic-models.R
@@ -17,6 +17,12 @@ OLSonTransformation <- function(mx, my, transformation) {
     } else {
         mx <- sapply(4:ncol(mx), function(i) transformation(m = mx[, c(1:3, i)]))
     }
+    if (ncol(mx) > 4) {
+        na <- which(apply(mx, 2, var) == 0)
+        if (length(na) > 0) {
+            mx[, na] <- NA
+        }
+    }
     solve(t(mx) %*% as.matrix(mx)) %*% t(mx) %*% as.matrix(my)
 }