แทนที่ค่าที่หายไป

# Inspect the feature
___(studentnetworkdata$RelationalNeighborSecond)

# Find the indices of the missing values
toReplace <- ___(is.na(studentnetworkdata$___))

# Replace the missing values with 0
studentnetworkdata$RelationalNeighborSecond[___] <- ___

# Inspect the feature again
___(___$___)