pick up nearest number from data set

[Xinhui]

In my case, we have three variables - the underlying price, the strike price, and the datadate. When the program picks up the strike price that is nearest to the underlying price, I also need it to consider the datadate. Please see the attached document for a sample. 

So basically, I need it to pick the nearest strike price within that given date.

For example, on 2011/1/16, the underlying price is 26.33. The closest strike price is 26.5. 

On 2011/1/17, the underlying price is 26.11 and the closest strike price is 26. 

[Xinhui]

In my case, we have three variables - the underlying price, the strike price, and the datadate. When the program picks up the strike price that is nearest to the underlying price, I also need it to consider the datadate. Please see the attached document for a sample. 

So basically, I need it to pick the nearest strike price within that given date.

For example, on 2011/1/16, the underlying price is 26.33. The closest strike price is 26.5. 

On 2011/1/17, the underlying price is 26.11 and the closest strike price is 26. 

[alexchien · Accepted solution]

If the underlying_price is a constant within a day, you can use a sort and data step to get the nearest strike price. 

data sample_new;
    set sample;
    diff = abs(underlying_price - strike);
run;

proc sort data = sample_new;
    by datadate diff;
run;

data nearest_price;
    set sample_new;
    by datadate diff;
    if first.datadate;
run;