You are not logged in.

How to test if a variable is a number

Scott Witte

Intermediate

  • "Scott Witte" started this thread

Posts: 382

Location: Milwaukee, WI USA

Occupation: Professional Photographer

  • Send private message

1

Saturday, October 25th 2014, 11:38pm

How to test if a variable is a number

I'm sure this basic question has been answered before but my forum searching isn't finding it.

Apparently if...NaN isn't part of the current KRP syntax?
Scott Witte
Tour de Force 360VR
Scott Witte Photography

Alexey Tkachenko

Professional

Posts: 770

Location: Russian Federation

Occupation: Interpreting, Building virtual tours

  • Send private message

2

Sunday, October 26th 2014, 10:49am

Check out this thread, maybe it will be of some help

if( testvariable conditions fail to evaluate for string variables etc
Regards,

Alexey

sachagriffin

Master

Posts: 1,857

Occupation: Virtual Tours - Photography - Krpano developer

  • Send private message

3

Sunday, October 26th 2014, 9:17pm

Make a function that adds 1 to the variable and if it returns NaN, that sucker ain't a number. ;-)
Ok lets try some off the cuff stuff. If it doesn't work, it should be easy to fix

Source code

 
1
2
3
4
5
6
7
8
9
10
11

<action name="test_numeric">
add(tvar_test_numeric,%1,1);
ifnot (tvar_test_numeric == NaN, set(is_numeric, true);,set(is_numeric,false);
</action>

set(myvar, 6);
test_numeric(get(myvar));
trace(is_numeric);
set(myvar, 6o);
test_numeric(get(myvar));
trace(is_numeric);
KRPano Developer: Portfolio ::Gigapixel Tagging Solutions - Porfolio 2 :: Facebook :: Twitter :: reddit.com/r/VirtualTour

Scott Witte

Intermediate

  • "Scott Witte" started this thread

Posts: 382

Location: Milwaukee, WI USA

Occupation: Professional Photographer

  • Send private message

4

Sunday, October 26th 2014, 9:19pm

Thanks Alexey,

Before asking my question I read that and spent a couple hours creating and testing my own if statements trying to resolve the simple but important condition, If(a variable is a number, then... because there is no NaN test this just isn't easy.

Here is the workaround I eventually stumbled on. Maybe it will help someone else. (I really can't believe this question hasn't been asked dozens of times before.) If you multiply a variable that is undefined or isn't a number by a number the result is Not a Number (NaN). So if you have a variable, testcase, that isn't a number:
mul(test, testcase, 2);
trace(get(test)); ==> NaN
Easy! But this is a condition, not a string so if you test,
if(test==NaN, ...
it will be false. The workaround is to convert the condition NaN into a string, 'NaN' and test that. So
set(test2, get(test));
if(test2==NaN,...
evaluates correctly. Curiously, even though the docs say, "The copy() action copies the content from one variable to the other one. This is the same like: set(destination, get(source) )".... that isn't exactly true. If you copy(test2, test) test2 will evaluate exactly like test. In other words it seems to copy the condition while set() converts the condition into a string. (Is this a bug or a feature?) So

Source code

 
1
2
3
4
5
6
7

set(testcase, t);
mul(test, testcase, 2);
trace(get(test));  ==> NaN
if(test==NaN,...  ==> tests false
set(test2,test);
trace(get(test2));  ==> NaN
if(test2==NaN,     ==> will be true

This is the only way I found to test if a variable is a number.

Klaus -- if you are listening, is this right? Maybe you can add an eval for NaN or am I missing something?
Scott Witte
Tour de Force 360VR
Scott Witte Photography

Scott Witte

Intermediate

  • "Scott Witte" started this thread

Posts: 382

Location: Milwaukee, WI USA

Occupation: Professional Photographer

  • Send private message

5

Sunday, October 26th 2014, 9:22pm

Howdy Sacha,

Thinking along the same lines! Except, as I found, you can't test the NaN result directly.
Scott Witte
Tour de Force 360VR
Scott Witte Photography

sachagriffin

Master

Posts: 1,857

Occupation: Virtual Tours - Photography - Krpano developer

  • Send private message

6

Sunday, October 26th 2014, 9:34pm

You're right!
Although on my tests, copy works. But I'm using the javascript console. Sometimes, things don't work the same.
KRPano Developer: Portfolio ::Gigapixel Tagging Solutions - Porfolio 2 :: Facebook :: Twitter :: reddit.com/r/VirtualTour

Scott Witte

Intermediate

  • "Scott Witte" started this thread

Posts: 382

Location: Milwaukee, WI USA

Occupation: Professional Photographer

  • Send private message

7

Sunday, October 26th 2014, 10:10pm

Quoted from "sachagriffin"

But I'm using the javascript console. Sometimes, things don't work the same.

Yup. Which can lead to rewarding hours hair pulling at times. Maybe that's why I no longer have any!
Scott Witte
Tour de Force 360VR
Scott Witte Photography

klaus.krpano

Administrator

Posts: 13,499

  • Send private message

8

Monday, October 27th 2014, 11:47am

Quoted from "Scott Witte"

Klaus -- if you are listening, is this right? Maybe you can add an eval for NaN or am I missing something?
Hi,

okay, I have added this is as feature request - I will think about a way for testing for NaN.

Best regards,
Klaus

Scott Witte

Intermediate

  • "Scott Witte" started this thread

Posts: 382

Location: Milwaukee, WI USA

Occupation: Professional Photographer

  • Send private message

9

Monday, October 27th 2014, 3:28pm

You're the best, Klaus.
Scott Witte
Tour de Force 360VR
Scott Witte Photography

dedaimiel

Beginner

Posts: 3

  • Send private message

10

Tuesday, February 18th 2020, 7:55pm

Quoted from "Scott Witte"

set(testcase, t);
mul(test, testcase, 2);
trace(get(test)); ==> NaN
if(test==NaN,... ==> tests false
set(test2,test);
trace(get(test2)); ==> NaN
if(test2==NaN, ==> will be true
Thanks Scott Witte

I tried your code but I think it dosen't work properly. At the end you say "if(test2==NaN, == will be true" perphaps it would be true but unfortunately it doesn't.

Inspired in your suggestion I did this other action I think work fine



Source code

 
1
2
3
4
5

<action name="test_numeric">
	set(test,calc(%1^2));
	if( test GT 0 , set(isNumber,true),set(isNumber,false));	
	 trace (isNumber); 
</action>


The advantage of this code is that you only get a value of true when the variable you pass to the action exist and is a number. If the var you pass is a string, is not define, or is null, the value of isNumber is false.

indexofrefraction

Professional

Posts: 1,362

  • Send private message

11

Tuesday, February 18th 2020, 9:21pm

javascript is your friend *rolleyes*

Source code

 
1
2
3

<action name="isnumber" type="javascript">
	krpano.set(args[1], !isNaN(Number(args[2])));
</action>
zFilter plugin -- zFlare plugin -- zSnapshot plugin

klaus.krpano

Administrator

Posts: 13,499

  • Send private message

12

Tuesday, February 18th 2020, 9:39pm

Hi,

that thread is outdated, krpano already has a build-in isNaN function:
https://krpano.com/docu/actions/#expressions.inlinefunctions

E.g. just:

Source code

 
1

if(isNaN(test), ...);


Best regards,
Klaus

dedaimiel

Beginner

Posts: 3

  • Send private message

13

Wednesday, February 19th 2020, 5:43pm

Quoted from "klaus.krpano"

that thread is outdated, krpano already has a build-in isNaN function:
https://krpano.com/docu/actions/#expressions.inlinefunctions
I knew the function "isNanN", but for me the problem of this function is this:

it works fine with strings

set(test,"b");
if(isNaN(test),trace('Its NOT number'),trace('Its a number')); ==> its NOT a number

or numbers

set(test,"4"); if(isNaN(test),trace('Its NOT number'),trace('Its a number')); ==> its a number

but when your have a empty, or not defined variable.

set(test,"");
if(isNaN(test),trace('Its NOT number'),trace('Its a number')); ==> its a number

set(test," ");
if(isNaN(test),trace('Its NOT number'),trace('Its a number')); ==> its a number

and if test is not defined
if(isNaN(test),trace('Its NOT number'),trace('Its a number')); ==> its a number




Best regards,
deDaimiel

klaus.krpano

Administrator

Posts: 13,499

  • Send private message

14

Wednesday, February 19th 2020, 11:42pm

Hi,

that's how isNaN() is working:
https://developer.mozilla.org/en-US/docs…NaN#Description

Empty strings are parsed as 0 value and 0 is a number...

But it would be possible to change the isNaN() function to the Javascript Number.isNaN() function, then checks for undefined variables would result in false.

Best regards,
Klaus

Similar threads