topic Re: rounding off to lower number in SAS Programming

rounding off to lower number

buddha_d — Mon, 13 Nov 2017 21:03:04 GMT

folks,

could you please help to round off numbers with sas function?

eg: 0.0015 or 0.0019 or 0.001595 or anything after 0.001.... should be 0.001 until it hit 0.002

thanks

Re: rounding off to lower number

Reeza — Mon, 13 Nov 2017 21:07:28 GMT

So truncation instead?

Always to the third decimal place or....?

Re: rounding off to lower number

PaigeMiller — Mon, 13 Nov 2017 21:10:32 GMT

If you want 3 decimal places

newvalue = floor(value*1000)/1000;

Re: rounding off to lower number

Reeza — Mon, 13 Nov 2017 21:18:55 GMT

Basically you need to use some math functions. FLOOR can be used, but rounds to integers so first round it to the nearest integer and then create it back as a decimal value.

Or here's another of the math tricks using ROUND() function:

z = round(x - 0.0005, 0.001);

Re: rounding off to lower number

Tom — Mon, 13 Nov 2017 21:36:07 GMT

You could also use the MOD() function.

  y = x - mod(x,0.001);

Which will work differently for negative numbers than the FLOOR(x*1000)/1000 option.

data test ;
  input x;
  y = x - mod(x,0.001);
  z = floor(x*1000)/1000;
cards;
0.0015
0.0019
0.001595
-0.00234
;

proc print; run;

Obs        x         y        z

 1     0.001500    0.001    0.001
 2     0.001900    0.001    0.001
 3     0.001595    0.001    0.001
 4     -.002340    -.002    -.003

FLOOR() will go down to -.003 since it is smaller than -.002340. The MOD() will instead look more like a truncation of the first few digits. Essentially finding the round number that is closer to zero.

Re: rounding off to lower number

PaigeMiller — Mon, 13 Nov 2017 21:35:33 GMT

@PaigeMiller wrote:

If you want 3 decimal places
newvalue = floor(value*1000)/1000;

I should add this doesn't give the desired answer for negative numbers, but it is easily fixed.

Re: rounding off to lower number

Astounding — Mon, 13 Nov 2017 21:37:52 GMT

Could your incoming values be negative as well as positive? Should -0.0015 round to -0.001 or to -0.002?

Depending on your answers, you might want to consider:

var = int(var * 1000) / 1000;

Re: rounding off to lower number

buddha_d — Mon, 13 Nov 2017 23:10:53 GMT

Thank you all for the comments. No, there are no negative numbers. Let me give more clarification:
For example :
0.0450000 (0.040000-0.0450000) round off to 0.04 and anything above it eg: 0.0450001 (0.0450001-0.0459999) round off to 0.05.
Please let me know if need more clarification. Thanks in advance.

Re: rounding off to lower number

Reeza — Mon, 13 Nov 2017 23:47:51 GMT

So how do we know how many decimals you want?

is 0.00453 becoming 0.0045 or 0.004?

Re: rounding off to lower number

buddha_d — Tue, 14 Nov 2017 00:01:35 GMT

We are rounding off to two digits. (eg: 0.065 is equals to 0.06 , 0.0650001 equals to 0.07).

thanks reeza for prompt reply.

Re: rounding off to lower number

Reeza — Tue, 14 Nov 2017 00:04:05 GMT

Any of the above approaches can be easily modified to work with a two decimal place solution. If you have issues implementing a specific solution post your code, log and DETAIL what issue you're receiving.

@buddha_d wrote:

We are rounding off to two digits. (eg: 0.065 is equals to 0.06 , 0.0650001 equals to 0.07).

thanks reeza for prompt reply.

Then why did you start off with one that rounded to three digits?

Re: rounding off to lower number

buddha_d — Tue, 14 Nov 2017 01:58:19 GMT

Sorry for putting it wrong first time . My problem (with any of the above code) is once the number shows as 0.005 or above (for round off two decimal), SAS would round off to 0.01. My case is even when it reaches 0.005, it should display as 0.00 (for 2 digit round off) . But if i give 0.0050001 then it should display as 0.01.

Have data:

0.0750001
0.0750000
0.0755920
0.0744999

0.0700001

want to display as:

0.08

0.07

0.08

0.07

I tried with above mentioned code manipulation and didn't find an answer.

Re: rounding off to lower number

Reeza — Tue, 14 Nov 2017 02:06:11 GMT

If you have issues implementing a specific solution post your code, log and DETAIL what issue you're receiving.

If you have issues implementing a specific solution post your code, log and DETAIL what issue you're receiving.

@buddha_d wrote:

Sorry for putting it wrong first time . My problem (with any of the above code) is once the number shows as 0.005 or above (for round off two decimal), SAS would round off to 0.01. My case is even when it reaches 0.005, it should display as 0.00 (for 2 digit round off) . But if i give 0.0050001 then it should display as 0.01.

Have data:

0.0750001
0.0750000
0.0755920
0.0744999

0.0700001

want to display as:

0.08

0.07

0.08

0.07

0.07

I tried with above mentioned code manipulation and didn't find an answer.

Re: rounding off to lower number

buddha_d — Tue, 14 Nov 2017 02:27:41 GMT

program, log and output are in the attachment

Re: rounding off to lower number

Reeza — Tue, 14 Nov 2017 03:31:18 GMT

Looks fine to me.

Re: rounding off to lower number

Astounding — Tue, 14 Nov 2017 03:38:46 GMT

I can test this now, but I think this would come close enough:

var = round(var - 1e-12, 0.01);

Re: rounding off to lower number

buddha_d — Tue, 14 Nov 2017 03:41:42 GMT

Man, Astounding awesome. Could you please give me logic for this??

thanks a ton......

Re: rounding off to lower number

Astounding — Tue, 14 Nov 2017 03:52:16 GMT

The basic idea is to round to the nearest 0.01. That would solve most of the problem, except that standard rounding would round 0.015 to 0.02 instead of 0.01. So subtract a tiny amount, and then round to the nearest 0.01. If you actually have a value that is 0.0150000000001, this formula will be incorrect and will round to 0.01 instead of 0.02. The "tiny amount" being subtracted would be enough to alter the result.

Re: rounding off to lower number

buddha_d — Tue, 14 Nov 2017 03:53:08 GMT

How can I adjust the formula for varying digits (bold letters) for eg:

data new;
input x;
var = round(x - 1e-12, 0.01);
cards;
0.0750001
0.0750000
0.0755920
0.0744999
0.0700001
0.050000001
0.049999999
;
run;

the results are:

0.08

0.07

0.08

0.07

0.05

Re: rounding off to lower number

Astounding — Tue, 14 Nov 2017 03:59:54 GMT

The next-to-last observation should be fine as is. The last observation is asking for a new set of rules, and you haven't presented any such rules. Here is another approach you can experiment with:

var = round(var, 0.00000001);

var = round(var, 0.01); or possibly var = round(var - 1e-10, 0.01);

By rounding twice, the 0.049999999 would become 0.05, then the second rounding wouldn't change the value. You might have to experiment with the number of decimal places to use in the first rounding, and whether you want to subtract that tiny amount for the second rounding.