I have a dataset with a variable "sex". I would like to know how can I replace a string value "missing" with a missing value (dot). Can you help me with the code?
I send an example of the dataset below. Thank. you very much


Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input byte(sex nchresp nch415resp)
1 0 0
1 0 0
2 0 0
1 0 0
2 2 2
2 1 1
1 0 0
2 0 0
2 0 0
2 0 0
2 2 1
2 0 0
1 0 0
1 2 1
1 0 0
2 2 2
2 0 0
2 0 0
2 2 2
2 2 2
1 1 0
2 0 0
1 0 0
1 0 0
2 0 0
2 0 0
2 0 0
1 0 0
2 0 0
2 0 0
2 2 1
2 3 3
1 0 0
1 0 0
2 0 0
2 2 2
2 0 0
1 0 0
1 0 0
2 1 1
1 0 0
1 0 0
2 0 0
1 0 0
2 1 1
2 3 1
1 0 0
2 0 0
1 0 0
2 0 0
2 0 0
1 0 0
2 1 0
2 1 0
1 0 0
1 0 0
1 0 0
2 1 1
1 0 0
2 1 0
2 0 0
2 1 1
1 0 0
2 0 0
2 0 0
1 0 0
1 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 1 1
1 0 0
2 0 0
1 0 0
1 0 0
2 0 0
1 0 0
2 0 0
2 0 0
1 0 0
2 0 0
1 0 0
2 0 0
2 3 3
1 0 0
2 0 0
1 0 0
2 1 1
1 0 0
2 0 0
2 2 0
2 2 1
1 0 0
2 1 1
2 0 0
2 2 2
2 0 0
1 0 0
2 0 0
end
label values sex c_sex
label def c_sex 1 "male", modify
label def c_sex 2 "female", modify
label values nchresp c_nchresp
label values nch415resp c_nch415resp