Error in loop: is.na() applied to non-(list or vector) of type 'NULL'

Question

I am trying to count NA values from every column in data frame like this

a = c('a', 'b', NA)

b = c('a', NA, NA)

c = c(NA, NA, NA)

data = data.frame(cbind(a, b, c))

This works

sum(is.na(data$a))

But when i tried using LOOP

for(i in data[, 1:3]) {

  k=sum(is.na(data$i)) 

  cat(k, '\n')

}

I am getting

Warning messages:

1: In is.na(data$i) :

  is.na() applied to non-(list or vector) of type 'NULL'

How do I fix it?

Answer 1

Use the loop to index the data frame

# use 1:3 as index for the columns

for(i in 1:3) {

  # instead of data$i; use data[ , i] to 

  # select all rows and the ith colum

  k=sum(is.na(data[ , i])) 

  cat(k, '\n')

}

If you want to know more about the Data Science then do check out the following Data Science which will help you in understanding Data Science from scratch