topic Extract the last character of a string / Extract only numeric values in an alphanumeric string in SAS Programming

Extract the last character of a string / Extract only numeric values in an alphanumeric string

_maldini_ — Thu, 18 Aug 2016 01:35:47 GMT

#1. I have a variable that contains alphanumeric strings of differing lengths. The last digit in each string is a character. I need to extract just the last digit of each string into a new variable. I was trying to use the SUBST function, but I don't know how to determine the position when the length of the string may change from observation to observation.

#2. Then, I need to extract only the numeric values in this same variable (e.g. xyz1333520M, x1234F). Again, the alphanumeric strings are of differing lengths. How can I extract just the numeric values (They are always sequential).

Thanks!

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

Reeza — Thu, 18 Aug 2016 01:44:45 GMT

1. Reverse(substr(string,1,1))

2. Compress(string, , 'kd');

Check the parameter order for compress, but use the modifiers to keep only digits

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

Tom — Thu, 18 Aug 2016 02:49:39 GMT

The LENGTH() function will tell you the location of the last non-blank character. (Note for empty strings it will return 1).

want = substr(have,length(have),1);

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

Ksharp — Thu, 18 Aug 2016 05:28:05 GMT

Then use LENGTHN()


data _null_;
x='xxx';n1=length(x);n2=lengthn(x);
put x= n1= n2=;

x=' ';n1=length(x);n2=lengthn(x);
put x= n1= n2=;

run;

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

_maldini_ — Fri, 19 Aug 2016 21:48:25 GMT

@Reeza

The result for Reverse(substr(string,1,1)) is the same as the result for (substr(string,1,1)). It seems like it's not picking up the "reverse".

What am I doing wrong here?

Thanks!

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

Reeza — Fri, 19 Aug 2016 21:56:26 GMT

Reverse the string and then take the substring.

Reversing a string of 1 is 1.

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

Tom — Fri, 19 Aug 2016 22:01:42 GMT

If the string is only one character string long then reversing it does nothing.

But if you applied the functions in the other order then you could still have problems because of trailing spaces. If you store 'ABC' into variable of length 5 then it will have two trailing spaces. If you reverse it there will be two leading spaces instead.

You could do

substr(reverse(trim(VAR)),1,1)

But it does seem like way too much work.

Re: Extract the last character of a string / Extract only numeric values in an alphanumeric string

_maldini_ — Fri, 19 Aug 2016 23:12:26 GMT

@Reeza

I understand the approach, but: 1) The strings are not 1 character in length (e.g. 13000M, x13260M); and 2) When the string is reversed, the syntax is still taking the character in the first position in the orginal, not reversed, string.

In other words, 13000M is new_var=1, both with, and without, the reverse function. Should new_var=M, given that the string was reversed? That's what I'm after...

When I use the functions separately the reverse function converts 13000M to M13000. When I then use the substring function, only a subset of the observations have the correct value. It's only the observations w/ the longest length (i.e. 7 characters). Any observation w/ less characters than that contains a missing value (See attached image).