/* module 3: problems 1a, 4, 6 */

/* 3.1a */

filename china 'China#1.dat';
*compute year-to-year change in exports;
data one;
infile china;
input year 1-4 gross 6-10 exports 12-16 imports 18-22;
d_export = exports - lag(exports);
run;
proc print data=one;
run;

/* 3.4 */
* ammendment: don't need to output to file. (already done);
data two;
input flavor $ 1-12 height 14-17 brand $ 19-31;
datalines;
Devil's food 39.0 Duncan Hines
Devil's food 36.5 Duncan Hines
White        30.5 Duncan Hines
White        34.5 Duncan Hines
Yellow       37.0 Duncan Hines
Yellow       35.0 Duncan Hines
;
run;
data three;
input flavor $ 1-12 height 14-17 brand $ 19-31;
datalines;
Yellow       35.5 Betty Crocker
Yellow       36.0 Betty Crocker
Devil's food 35.5 Betty Crocker
Devil's food 37.5 Betty Crocker
White        32.5 Betty Crocker
White        32.5 Betty Crocker
;
run;
filename cakecat 'cakes.txt';
filename cakemerg 'cakes2.txt';
data cakes;
  set two three;
  file cakecat;
  put @1 flavor @14 height @19 brand;
run;
proc print data=cakes;
run;
data four; /* rename variables to keep through match merge */
  set three;
  height2 = height;
  brand2 = brand;
run;
proc sort data=two;
  by flavor;
run;
proc sort data=four;
  by flavor;
run;
data cakesm;
  merge four two; /* dataset four listed first for proper merge */
  by flavor;
  file cakemerg;
  put @1 flavor @14 height @19 brand @33 height2 @38 brand2;
run;
proc print data=cakesm;
run;

/* 3.6 */
* use only propane, internet service, and home security system in input from file;
filename moonlake 'moonlake.dat';
data five;
  infile moonlake firstobs=26 obs=50;
  input propane 1 internet 9 homesec 10;
run;
data six;
  infile moonlake firstobs=251 obs=300;
  input propane 1 internet 9 homesec 10;
run;
data fivesix;
  set five six;
run;
proc print data=fivesix;
run;