topic Re: turning null into 0 when reading from files in SAS Programming

turning null into 0 when reading from files

HeatherNewton — Tue, 23 Jan 2024 04:11:18 GMT

do you know if sas automatically turn null into 0 in any case?

in what I see, when sas read in from files other than sas dataset

it turn null into zero

why is this??

our files are iff, lets say it is some text file

Re: turning null into 0 when reading from files

mkeintz — Tue, 23 Jan 2024 05:49:15 GMT

Assuming by "null", you mean a blank character, and assuming you are reading values via the INPUT statement, then SAS does NOT by default convert a null into a zero (we are discussing numeric variables here). Instead, the numeric variable is assigned a special missing value (typically printed out as a naked period), when read from a "null".

I.e. this program:

data t;
  input @1 x 1.  @3 y 1. ;
  put (_all_) (=);
datalines;
1 1
2  
  3
run;

produces this on the sas log (note the dots).

x=1 y=1
x=2 y=.
x=. y=3
NOTE: The data set WORK.T has 3 observations and 2 variables.

A missing value, by default, is not treated as a zero, although there are some SAS functions and statements that can treat missing values as zeroes.

Re: turning null into 0 when reading from files

andreas_lds — Tue, 23 Jan 2024 07:52:20 GMT

If a data step is used to read the files, a custom informat could change missing (aka null) to 0 automatically.

Re: turning null into 0 when reading from files

Amir — Tue, 23 Jan 2024 08:21:51 GMT

Hi,

Please share an example data step with instream data (e.g., datalines), so that we can replicate the issue to assist with a solution.

Depending upon how you are reading in the data and viewing it, the missing= option might be worth checking, as the page says "Specifies the character to print for missing numeric values."

Thanks & kind regards,

Amir.

Re: turning null into 0 when reading from files

ballardw — Tue, 23 Jan 2024 10:03:00 GMT

@HeatherNewton wrote:

do you know if sas automatically turn null into 0 in any case?

in what I see, when sas read in from files other than sas dataset

it turn null into zero

why is this??

our files are iff, lets say it is some text file

What is your current setting for the MISSING option? You can check by running this code:

Proc options option=missing;
run;

The output in the log will look something like:

49   Proc options option=missing;
50   run;

    SAS (r) Proprietary Software Release 9.4 

 MISSING=.         Specifies the character to print for missing numeric
                   values.

If your result shows Missing=0 then your setting is displaying zero when the value is missing.

Otherwise show the code you are using to read one of these files and a few lines of the text file data that exhibit this behavior.

Re: turning null into 0 when reading from files

PaigeMiller — Tue, 23 Jan 2024 12:06:17 GMT

@HeatherNewton

Unless you have subject matter knowledge that allows you to know that null should be treated as zeros, do NOT do this. Nulls should be treated as missing without such subject matter knowledge.

Re: turning null into 0 when reading from files

PaigeMiller — Wed, 24 Jan 2024 11:04:08 GMT

@HeatherNewton please mark one of the above replies as correct, whichever one you think is correct.

Re: turning null into 0 when reading from files

MelissaM — Wed, 24 Jan 2024 16:39:50 GMT

I was so hoping someone would mention that 'missing information' is rarely equal to a numeric 'zero'. Thank you, Paige, for calling this out! 🙂