[R] how to delete columns with NA values?

[Erik Iverson]

Hello,

muting wrote:
> Hi everyone:
> 
> I have a dataset:

This looks like a matrix.  To perform functions on each row or column of 
a matrix, use the apply function.

If you had a data.frame, you could perform a function on each column 
using sapply or lapply.
> 
> tm1
>      col1 col2
> [1,]    1   NA
> [2,]    1    1
> [3,]    2    2
> [4,]    1    1
> [5,]    2    2
> [6,]    1   NA
> 
> I need to delete entire column 2 that has NA in it(not all of them are NAs),
> and the result I want is
> 
> tm1
>      col1 
> [1,]    1  
> [2,]    1    
> [3,]    2    
> [4,]    1    
> [5,]    2    
> [6,]    1   
> 
> what should I do? 

## for a data.frame x
x <- data.frame(a = 1:10, b = c(2:10, NA), c = 2:11)

x[sapply(x, function(x) !any(is.na(x)))]

## for a matrix y
y <- matrix(1:30, ncol = 3)
y[20] <- NA

y[, apply(y, 2, function(x) !any(is.na(x)))]

## or maybe even simply...
y[,complete.cases(t(y))]