substr

SAS day 6 : Substr

SAS Substr is a common function for building datasets. It is used for extracting partial information from variables.

Syntax:

SUBSTR(variable, position, desired length)

Substr extracts a substring from a variable starting at “position” for “desired length” characters.

Example:

In ADPE, we use substr to create pevisit.

VISIT:      CYCLE 10 DAY 1

pevisit= substr(VISIT, 1, 8)

pevisit:   CYCLE 10

Problem:
Now we want to extract the records of variable a that have “.1” as the last two digits. Note the length varies for each record.

1CYCLE 1 DAY 1
2CYCLE 1 DAY 8
3CYCLE 1 DAY 28
4CYCLE 1 DAY 28.1

R391n4 / Pixabay

Solution:

1. Apply Stripcommand to remove the ending empty space for variable a.

2. Apply Reverse to reserve the order the variable a

3. Apply Substr to extract the first two digits.

Code:

substr(reverse(strip(visit)), 1 ,2)=”1.”

Output:

CYCLE1 DAY 28.1

an alternative solution would use Index function.

Happy SAS Coding!