SAS: can the COUNT() function be used for categorical variables? - count

Question

The categorical variable is "unique_carrier", which is as follows:
enter image description here
I want to count the number of each carrier in the variable "unique_carrier", My codes in SAS are as below,
PROC MEANS DATA=schedule_Jan NOPRINT;
BY unique_carrier _CHARACTER_ ;
OUTPUT OUT= flight_count COUNT(unique_carrier) =number_of_flights;
RUN;
but things go wrong when run this line (as below), and the log is, I wonder whether the COUNT function can be used for count categorical variable:
222 OUTPUT OUT= flight_count COUNT(unique_carrier) =number_of_flights;
-----
22
76
ERROR 22-322: Syntax error, expecting one of the following: ;, (, /, CSS, CV, IDGROUP, IDGRP,
KURTOSIS, LCLM, MAX, MAXID, MEAN, MEDIAN, MIN, MINID, MODE, N, NMISS, OUT, P1,
P10, P20, P25, P30, P40, P5, P50, P60, P70, P75, P80, P90, P95, P99, PROBT, Q1,
Q3, QRANGE, RANGE, SKEWNESS, STDDEV, STDERR, SUM, SUMWGT, T, UCLM, USS, VAR.
ERROR 76-322: Syntax error, statement will be ignored.

Answer 1

You can get the count by using PROC FREQ.
proc freq data=schedule_Jan ;
tables unique_carrier / noprint out=flight_count ;
run;
This will have the number of observations per value of UNIQUE_CARRIER in the variable COUNT. You could add a dataset option to rename it to NUMBER_OF_FLIGHTS if you want.
Or you can use PROC MEANS (aka PROC SUMMARY).
proc summary data=schedule_Jan nway;
class unique_carrier;
output out=flight_count ;
run;
This will have the number of observations in the variable _FREQ_. You could use dataset option to rename this or add N=number_of_flights to the OUTPUT statement to add another variable with the same count.
Or you could even 'roll your own' by writing some SQL code.
proc sql ;
create table flight_count as
select unique_carrier
, count(*) as number_of_flights
from schedule_Jan
group by 1
order by 1
;
quit;