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Re: round to x number of decimals within floating point value? [message #74333]

Thu, 13 January 2011 16:07

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Paulo Penteado writes:

> Is this a non-default finite()? The one I know takes an argument,
> returning whether the elements are finite numbers (not infinity or
> NaN).

Sorry, totally asleep at the wheel. :-(

goodval = where(finite(array) EQ 1, count)

This is the way I usually screen for NANs. Keywords can add
specificity, but this typically works for me. I don't usually
care *why* a value is bad. I just want to work with good values.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: round to x number of decimals within floating point value? [message #74335 is a reply to message #74333]

Thu, 13 January 2011 15:55

penteado
Messages: 866
Registered: February 2018

Senior Member
Administrator

On Jan 13, 5:35 pm, David Fanning <n...@dfanning.com> wrote:
> Snow53 writes:
>> I need to round the values within a file to three decimal places. For
>> example, 0.00053335 would become 0.001.
>> I also have many NaNs within the file.
>
> goodval = where(array EQ Finite(), count)
> if count gt 0 then begin
> array[gooval] = Float(Round(array[goodval]*1000)/1000.)
> endif

Is this a non-default finite()? The one I know takes an argument,
returning whether the elements are finite numbers (not infinity or
NaN).

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Re: round to x number of decimals within floating point value? [message #74352 is a reply to message #74335]

Thu, 13 January 2011 11:40

Snow53
Messages: 32
Registered: July 2010

Member

On Jan 13, 12:35 pm, David Fanning <n...@dfanning.com> wrote:
> Snow53 writes:
>> I need to round the values within a file to three decimal places. For
>> example, 0.00053335 would become 0.001.
>> I also have many NaNs within the file.
>
> goodval = where(array EQ Finite(), count)
> if count gt 0 then begin
> array[gooval] = Float(Round(array[goodval]*1000)/1000.)
> endif
>
> Cheers,
>
> David
>
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.idlcoyote.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

Sweet! Thanks :)

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Re: round to x number of decimals within floating point value? [message #74353 is a reply to message #74352]

Thu, 13 January 2011 11:35

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Snow53 writes:

> I need to round the values within a file to three decimal places. For
> example, 0.00053335 would become 0.001.
> I also have many NaNs within the file.

goodval = where(array EQ Finite(), count)
if count gt 0 then begin
array[gooval] = Float(Round(array[goodval]*1000)/1000.)
endif

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: round to x number of decimals within floating point value? [message #74442 is a reply to message #74333]

Fri, 14 January 2011 07:16

Kenneth P. Bowman
Messages: 585
Registered: May 2000

Senior Member

In article <MPG.279941936212ce0e98992d@news.giganews.com>,
David Fanning <news@dfanning.com> wrote:

> goodval = where(finite(array) EQ 1, count)

The equality test is unnecessary, so you can write

goodval = where(finite(array), count)

to find the good values and

badval = where(~finite(array), count)

to find the bad values. And of course you can do both
with a single WHERE and appropriate keywords.

Cheers, Ken

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