is.na function in r code example

Example 1: if not na in r

which( !is.na(p), arr.ind=TRUE)

Example 2: na by column r

df <- data.frame(x = c(1,2,NA), y = rep(NA, 3))

# Which column has na?
colSums(is.na(df))[colSums(is.na(df)) > 0]

# which rows?
df[which(rowSums(is.na(df)) > 0),]