Categorizing values within a single variable via loop

[Shaun Redden]

Good evening,

I am new to Stata and have been researching and consulting the help command on a problem with no luck.

I am trying to create a new variable "hour_groups" that categorizes the "hour" variable into 4 groups, e.g. 0 to 6 (a.m.) is assigned the number 1, 7 to 12 is assigned 2 and so on. I'm trying the foreach and and forvalues command. Any help is appreciated. Is it possible to generate a new variable while categorizing in the same command?

[Carlo Lazzaro]

Shaun:
welcome to this forum.
No loop needed here:

. set obs 24
number of observations (_N) was 0, now 24

. g hours=_n

. g hours_group=1 if hours<=6 & hours!=.
(18 missing values generated)

. replace hours_group=2 if hours<=12 & hours_group==. & hours!=.
(6 real changes made)

. replace hours_group=3 if hours<=18 & hours_group==. & hours!=.
(6 real changes made)

. replace hours_group=4 if hours_group==. & hours!=.
(6 real changes made)

. list

     +------------------+
     | hours   hours_~p |
     |------------------|
  1. |     1          1 |
  2. |     2          1 |
  3. |     3          1 |
  4. |     4          1 |
  5. |     5          1 |
     |------------------|
  6. |     6          1 |
  7. |     7          2 |
  8. |     8          2 |
  9. |     9          2 |
 10. |    10          2 |
     |------------------|
 11. |    11          2 |
 12. |    12          2 |
 13. |    13          3 |
 14. |    14          3 |
 15. |    15          3 |
     |------------------|
 16. |    16          3 |
 17. |    17          3 |
 18. |    18          3 |
 19. |    19          4 |
 20. |    20          4 |
     |------------------|
 21. |    21          4 |
 22. |    22          4 |
 23. |    23          4 |
 24. |    24          4 |
     +------------------+

.

See also -help label if you want to take the matter further.

[Wouter Wakker]

No loop necessary I reckon. You can do it all in one command with recode, see help recode.

[Nick Cox]

The scheme you ask for is not consistent as 0 to 6 is 7 hours, 7 to 12 is 6 hours, etc. Nevertheless the main point is that absolutely no loop is needed here. If how to change this to get exactly what you want is not clear to you, then please do as we ask and give a data example (FAQ Advice #12).

clear
set obs 24
gen hours = _n
gen wanted = ceil(hours/6)
list, sepby(wanted)

    +----------------+
     | hours   wanted |
     |----------------|
  1. |     1        1 |
  2. |     2        1 |
  3. |     3        1 |
  4. |     4        1 |
  5. |     5        1 |
  6. |     6        1 |
     |----------------|
  7. |     7        2 |
  8. |     8        2 |
  9. |     9        2 |
 10. |    10        2 |
 11. |    11        2 |
 12. |    12        2 |
     |----------------|
 13. |    13        3 |
 14. |    14        3 |
 15. |    15        3 |
 16. |    16        3 |
 17. |    17        3 |
 18. |    18        3 |
     |----------------|
 19. |    19        4 |
 20. |    20        4 |
 21. |    21        4 |
 22. |    22        4 |
 23. |    23        4 |
 24. |    24        4 |
     +----------------+