strings as factors

Hi,
To be able to match cases with a benchmark I need to have a data.frame with 
a character id variable. however, I am surprised why this seems to be so 
hard. In fact I was  unable to succeed. Here is what I tried:

test1 <-expand.grid(ID = 1:2, sex = c("male","female"))
is(test1[,2])

[1] "factor"   "oldClass"

test2 <-expand.grid(ID = 1:2, sex = c('male','female'))
is(test2[,2])

[1] "factor"   "oldClass"

test3 <-expand.grid(ID = 1:2, sex = I(c("male","female")))
is(test3[,2])

[1] "factor"   "oldClass"

test4 <-expand.grid(ID = 1:2, sex = I(c('male','female')))
is(test4[,2])

[1] "factor"   "oldClass"

options(stringsAsFactors = FALSE)
options("stringsAsFactors")

$stringsAsFactors
[1] FALSE

test5 <-expand.grid(ID = 1:2, sex = I(c('male','female')))
is(test5[,2])

[1] "factor"   "oldClass"


is there anyway I can get sex to be a character?

Arnab

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