SAS | COALESCE Function with Examples

• Last Updated : 30 Jul, 2019

The COALESCE function is employed to pick the first non-missing value in a list of variables. In other words, it returns the first non-blank value of each row.

Let’s produce a sample dataset in SAS to know how COALESCE perform.

Example:

 data temp;    input roll_no a1-a4;    cards;12 . 98 52 .         23 79 . 67 .         14 90 82 88 85 ;run;

Output: • COALESCE : First Non-Missing Value
 data exam;set temp;first_non_miss_val = coalesce(of a1 - a4);run;

If you examine the output shown within the image below, you’d realize COALESCE returns 98 in first observation which is the first non-missing value among a1 = ., a2 = 98, a3 = 52, a4 =. • COALESCE : Last Non-Missing Value

Let us suppose you want to find out last non-missing value instead of first. For that, there is no such function available which will return last non-missing value but to achieve that we can reverse the list of variables and calculate the first non-missing value which would be equivalent to last non-missing value. Indirectly, we are considering to evaluate variables from right to left instead of left to right.

 data exam;set temp;last_non_miss_val = coalesce(of a4-a1);run;

Output: Note: coalesce(of a4-a1) is equivalent to coalesce(a4, a3, a2, a1).

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