[R] missing and replace

[Val]

HI all,

I have a data frame with three variables. Some of the variables do
have missing values and I want to replace those missing values
(1represented by NA) with the mean value of that variable. In this
sample data,  variable z and y do have missing values. The mean value
of y  and z are152. 25  and 359.5, respectively . I want replace those
missing values  by the respective mean value ( rounded to the nearest
whole number).

DF1 <- read.table(header=TRUE, text='ID1 x y z
1  25  122    352
2  30  135    376
3  40   NA    350
4  26  157    NA
5  60  195    360')
mean x= 36.2
mean y=152.25
mean z= 359.5

output
ID1  x  y  z
1   25 122   352
2   30 135   376
3   40 152   350
4   26 157   360
5   60 195   360


Thank you in advance