Converting measurement occasions to numbers

[Job04]

I have bi-weekly measurements and in total 23 measurements per country. I want to convert the days of measurements which corresponds to days in  months to simply numbering these measurement occasions from 1 to 23 for all countries. I want them to be categorical. Thank you. 

location,day
Austria,14
Austria,28
Austria,11
Austria,25
Austria,11
Austria,25
Austria,8
Austria,22
Austria,6
Austria,20
Austria,3
Austria,17
Austria,1
Austria,15
Austria,29
Austria,12
Austria,26
Austria,9
Austria,23
Austria,7
Austria,21
Austria,4
Austria,18
Belgium,14
Belgium,28
Belgium,11
Belgium,25
Belgium,11
Belgium,25
Belgium,8
Belgium,22
Belgium,6
Belgium,20
Belgium,3
Belgium,17
Belgium,1
Belgium,15
Belgium,29
Belgium,12
Belgium,26
Belgium,9
Belgium,23
Belgium,7
Belgium,21
Belgium,4
Belgium,18
Bulgari,14
Bulgari,28
Bulgari,11
Bulgari,25
Bulgari,11
Bulgari,25
Bulgari,8
Bulgari,22
Bulgari,6
Bulgari,20
Bulgari,3
Bulgari,17
Bulgari,1
Bulgari,15
Bulgari,29
Bulgari,12
Bulgari,26
Bulgari,9
Bulgari,23
Bulgari,7
Bulgari,21
Bulgari,4
Bulgari,18

[Reeza · Accepted solution]

data want;
set have;
by location;
if first.location then counter=0;
counter+1;
run;

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I want them to be categorical.

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I don't know what 'them to be categorical' means.

Spoiler

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@Job04 wrote:

I have bi-weekly measurements and in total 23 measurements per country. I want to convert the days of measurements which corresponds to days in  months to simply numbering these measurement occasions from 1 to 23 for all countries. I want them to be categorical. Thank you. 

location,day
Austria,14
Austria,28
Austria,11
Austria,25
Austria,11
Austria,25
Austria,8
Austria,22
Austria,6
Austria,20
Austria,3
Austria,17
Austria,1
Austria,15
Austria,29
Austria,12
Austria,26
Austria,9
Austria,23
Austria,7
Austria,21
Austria,4
Austria,18
Belgium,14
Belgium,28
Belgium,11
Belgium,25
Belgium,11
Belgium,25
Belgium,8
Belgium,22
Belgium,6
Belgium,20
Belgium,3
Belgium,17
Belgium,1
Belgium,15
Belgium,29
Belgium,12
Belgium,26
Belgium,9
Belgium,23
Belgium,7
Belgium,21
Belgium,4
Belgium,18
Bulgari,14
Bulgari,28
Bulgari,11
Bulgari,25
Bulgari,11
Bulgari,25
Bulgari,8
Bulgari,22
Bulgari,6
Bulgari,20
Bulgari,3
Bulgari,17
Bulgari,1
Bulgari,15
Bulgari,29
Bulgari,12
Bulgari,26
Bulgari,9
Bulgari,23
Bulgari,7
Bulgari,21
Bulgari,4
Bulgari,18

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