Create table for asclogit and nlogit - stata

Question

Suppose I have the following table:
id | car | sex | income
-------------------------------
1 | European | Male | 45000
2 | Japanese | Female | 48000
3 | American | Male | 53000
I would like to create the one below:
| id | car | choice | sex | income
--------------------------------------------
1.| 1 | European | 1 | Male | 45000
2.| 1 | American | 0 | Male | 45000
3.| 1 | Japanese | 0 | Male | 45000
| ----------------------------------------
4.| 2 | European | 0 | Female | 48000
5.| 2 | American | 0 | Female | 48000
6.| 2 | Japanese | 1 | Female | 48000
| ----------------------------------------
7.| 3 | European | 0 | Male | 53000
8.| 3 | American | 1 | Male | 53000
9.| 3 | Japanese | 0 | Male | 53000
I would like to fit an asclogit and according to Example 1 in Stata's Manual, this table format seems necessary. However, i have not found a way to create this easily.

Answer 1

You can use the cross command to generate all the possible combinations:
clear
input byte id str10 car str8 sex long income
1 "European" "Male" 45000
2 "Japanese" "Female" 48000
3 "American" "Male" 53000
end
generate choice = 0
save old, replace
keep id
save new, replace
use old
rename id =_0
cross using new
replace choice = 1 if id_0 == id
replace sex = cond(id == 2, "Female", "Male")
replace income = cond(id == 1, 45000, cond(id == 2, 48000, 53000))
Note that the use of the cond() function here is equivalent to:
replace sex = "Male" if id == 1
replace sex = "Female" if id == 2
replace sex = "Male" if id == 3
replace income = 45000 if id == 1
replace income = 48000 if id == 2
replace income = 53000 if id == 3
The above code snipped produces the desired output:
drop id_0
order id car choice sex income
sort id car
list, sepby(id)
+------------------------------------------+
| id car choice sex income |
|------------------------------------------|
1. | 1 American 0 Male 45000 |
2. | 1 European 1 Male 45000 |
3. | 1 Japanese 0 Male 45000 |
|------------------------------------------|
4. | 2 American 0 Female 48000 |
5. | 2 European 0 Female 48000 |
6. | 2 Japanese 1 Female 48000 |
|------------------------------------------|
7. | 3 American 1 Male 53000 |
8. | 3 European 0 Male 53000 |
9. | 3 Japanese 0 Male 53000 |
+------------------------------------------+
For more information, type help cross and help cond() from Stata's command prompt.

Answer 2

Please see dataex in Stata for how to produce data examples useful in web forums. (If necessary, install first using ssc install dataex.)
This could be an exercise in using fillin followed by filling in the missings.
* Example generated by -dataex-. To install: ssc install dataex
clear
input byte id str10 car str8 sex long income
1 "European" "Male" 45000
2 "Japanese" "Female" 48000
3 "American" "Male" 53000
end
fillin id car
foreach v in sex income {
bysort id (_fillin) : replace `v' = `v'[1]
}
list , sepby(id)
+-------------------------------------------+
| id car sex income _fillin |
|-------------------------------------------|
1. | 1 European Male 45000 0 |
2. | 1 American Male 45000 1 |
3. | 1 Japanese Male 45000 1 |
|-------------------------------------------|
4. | 2 Japanese Female 48000 0 |
5. | 2 European Female 48000 1 |
6. | 2 American Female 48000 1 |
|-------------------------------------------|
7. | 3 American Male 53000 0 |
8. | 3 European Male 53000 1 |
9. | 3 Japanese Male 53000 1 |
+-------------------------------------------+

Answer 3

A provisional solution using Pandas in Python is the following:
1) Open the base with:
df = pd.read_stata("mybase.dta")
2) Use the code of the accepted answer of this question.
3) Save the base:
df.to_stata("newbase.dta")

Answer 4

If one wants to use dummy variables, reshape also is an option.
clear
input byte id str10 car str8 sex long income
1 "European" "Male" 45000
2 "Japanese" "Female" 48000
3 "American" "Male" 53000
end
tabulate car, gen(choice)
reshape long choice, i(id)
label define car 2 "European" 3 "Japanese" 1 "American"
drop car
rename _j car
label values car car
list, sepby(id)
+------------------------------------------+
| id car sex income choice |
|------------------------------------------|
1. | 1 American Male 45000 0 |
2. | 1 European Male 45000 1 |
3. | 1 Japanese Male 45000 0 |
|------------------------------------------|
4. | 2 American Female 48000 0 |
5. | 2 European Female 48000 0 |
6. | 2 Japanese Female 48000 1 |
|------------------------------------------|
7. | 3 American Male 53000 1 |
8. | 3 European Male 53000 0 |
9. | 3 Japanese Male 53000 0 |
+------------------------------------------+