[R] If statement

[Val]

Hi all,

I am trying to use the  if else statement and create  two new columns
based on the existing two columns.  Below please find my sample data,

dat1 <-read.table(text="ID  a b c d
A private couple  25 35
B private single  24 38
C none  single    28 32
E none none 20 36 ",header=TRUE,stringsAsFactors=F)

dat1$z <- "Zero"
dat1$y <-  0

if a is "private" and (b is either "couple" rr "single"
    then  z value = a's value   and y value = c's value
if a is "none" and  ( b is either couple of single then  z= private
  then  z value =b's value  qnd  y value= d's value
else z value= Zero and y value=0

the desired out put looks like
ID          a      b      c     d     z       y
1  A private couple 25 35 private 25
2  B private single 24 38 private 24
3  C    none single 28 32 single  32
4  E    none   none 20 36 Zero    0

my attempt

if (dat1$a =="private"  &  (dat1$b =="couple"| dat1$b =="single"))
{
      dat1$z      <-   dat1$a
      dat1$y      <-   dat1$c
}

else if (dat1$a =="none"  &  (dat1$b =="couple"| dat1$b =="single")) {
    dat1$z      <-   dat1$b
    dat1$y      <-   dat1$c
  }
else
{ default value}
did not wok, how could I fix this?
Thank you in advance