data z1;
put _ALL_;
    set sashelp.class;
    put _ALL_;
    weight2 = weight / 2;
    put _ALL_;
run;

*zliczenia;
*chcemy obliczyć wartość samochodów w help.cars;
data z2;
    set sashelp.cars end=koniec;

    retain total 0; /* zapamiętaj zmienna wartość_po */
    total = total + invoice;

    /* total + invoice */
    if koniec then output;
run;

*przetwarzanie w grupach;
proc sort data = sashelp.cars out=cars;
    by make; /* zmienna grupująca */
run;


data z3;
    set cars;
    by make; /* przetwarzanie w grupach */
    col1 = first.make;
    col2 = last.make;
run;


data z3;
    set cars;
    by make; /* przetwarzanie w grupach */
    /*col1 = first.make;
    col2 = last.make; */

    if first.make then do;
        licznik = 0;
        suma = 0;
    end;

    licznik + 1;
    suma + invoice;

    if last.make then output;
    keep make licznik suma;
run;


*sashelp.air;

data z4;
    set sashelp.air;
    rok = year(date);
run;


Proc sort data = z4 out = z4;
    by rok;
run;

data z5;
    set z4;
    by rok;

    if first.rok then suma = 0;

    suma + air;

    if last.rok then output;
    keep rok suma;
run;

*podaj 3 najdroższe auta dla każdej marki;
proc sort data=sashelp.cars out=cars;
    by make descending invoice;
run;

data z6;
    set cars;
    by make;
    if first.make then licznik = 0;

    licznik + 1;

    if licznik <= 3 then output;
run;