SAS缺少值

/* 定义用户定义的缺少值 */
proc format;
  value missingfmt .a .b .c;
run;

/* 使用用户定义的缺少值 */
data example;
  input id $ value;
  format value missingfmt.;
cards;
A 1
B .
C 3
D .a
E .b
F .c
G 7
run;

/* 删除含有缺少值的观测 */
proc delete data=example missing=(value);
run;

/* 填充缺少值 */
proc means data=example noprint;
  var value;
  output out=meanfill mean=mean_value;
run;

data example_filled;
  merge example meanfill;
  by _all_;
  if missing(value) then value = mean_value;
run;

/* 忽略缺少值 */
proc means data=example noprint;
  var value;
  output out=meanignore missing=(value);
run;

/* 使用插值方法填充缺少值 */
proc interpol;
  data example;
  input id $ value;
  format value missingfmt.;
cards;
A 1
B .
C 3
D .a
E .b
F .c
G 7
run;

proc interpol data=example;
  var value;
  output out=example_interpol;
run;