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Adds a new level called "NA" to any discrete predictor in a data frame that contains NAs. Stops if any continuous predictor contains an NA.
"NA"
NA
na.tree.replace(frame)
data frame such that a new level named "NA" is added to any discrete predictor in frame with NAs.
frame
data frame used to grow a tree.
This function is used via the na.action argument to tree.
na.action
tree
tree, na.omit.
na.omit