summing and subtracting when there is missing

[Emad Noureldeen]

Hello,
I try to generate a variable that is includes missing, how can I ignore these missing values

A002112000 A002113000 A002114000 A002115000 A0i2116000 A0i2117000
7.851e+09 2.904e+10
862729.14 -1401101.7 0 212157.58 0 0
1142823 2853657.8 0 8015518.9 0 0
2490640.9 7834515.8 0 3013278 0 0
2170997.8 3045616 0 2813278 0 0
2003422.3 1464629.9 2813278
1995585.5 4733366.3 2813278


I need to generate HH=A002112000 + A002113000 - A002114000 - A002115000 - A0i2116000 - A0i2117000

[Nick Cox]

help mvencode

Or know that

cond(missing(x), 0,  x)

treats missings in x as if they were zeros, so ignores them in addition and subtraction.

[Carlo Lazzaro]

Emad:
the easiest approach that springs to my mind is to flag observations with missing value in any of the variables;
1) change . in zero;
2) do the calculation;
3) trasform back to . when finished:

. egen flag=rowmiss( A002112000-A0i2117000)

.  foreach var of varlist A002112000 - A0i2117000 {
  2.replace `var'=0 if `var'==.
  3.}

. generate HH=A002112000 + A002113000 - A002114000 - A002115000 - A0i2116000 - A0i2117000 if flag>0

.  foreach var of varlist A002112000 - A0i2117000 {
  2. replace `var'=. if `var'==0 & flag>0
  3. }


.

PS: tragically inefficient when contrasted against Nick's elegant solution!

[Nick Cox]

I'd be reluctant to use such long variable names.

A002112000  A002113000 A002114000 A002115000  A0i2116000  A0i2117000

Do you need the trailing 000 ? Is there scope for names that mean something to the researcher?

[daniel klein]

I'd be reluctant to "ignore" missing values; if one or more values is missing, we naturally cannot know the result either.

[Emad Noureldeen]

help mvencode

Or know that

cond(missing(x), 0, x)

treats missings in x as if they were zeros, so ignores them in addition and subtraction.

Thanks very much, it is working

[Emad Noureldeen]

Emad:
the easiest approach that springs to my mind is to flag observations with missing value in any of the variables;
1) change . in zero;
2) do the calculation;
3) trasform back to . when finished:

. egen flag=rowmiss( A002112000-A0i2117000)

. foreach var of varlist A002112000 - A0i2117000 {
2.replace `var'=0 if `var'==.
3.}

. generate HH=A002112000 + A002113000 - A002114000 - A002115000 - A0i2116000 - A0i2117000 if flag>0

. foreach var of varlist A002112000 - A0i2117000 {
2. replace `var'=. if `var'==0 & flag>0
3. }


.

PS: tragically inefficient when contrasted against Nick's elegant solution!

Thanks very much. Yes it is long :D compared to the Nick's code