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Re: avoiding "floating illegal operand" errors with /nan keyword in mean [message #85599 is a reply to message #85598]

Tue, 20 August 2013 17:26

wlandsman
Messages: 743
Registered: June 2000

Senior Member

Does setting !except=0 work for you? --Wayne

On Tuesday, August 20, 2013 7:37:29 PM UTC-4, Paul Levine wrote:
> I have an array with 2800 rows, 2800 columns, and 120 layers, where
>
> each layer is a month from a 10-year time series). I would like to
>
> calculate annual means, so I will end up with an array that is 2800 x
>
> 2800 x 10. So
>
>
>
> for j = 0, 9 do begin
>
> ; make one year subset of 2800x1800x12
>
> subset = array[*,*,j*12:j*12+12]
>
> newarray[0,0,j] = mean(newarray, dimension=3, /nan)
>
> endfor
>
>
>
> I am using the /nan keyword because there are a lot of NaNs in the
>
> data. As a result, I get
>
> % Program caused arithmetic error: Floating illegal operand
>
> whenever the mean function tries to calculate an average completely out
>
> of NaN values.
>
>
>
> I know that I could just ignore the error, because the results are what
>
> I want them to be, but I'm sure it would be better to figure out how to
>
> prevent the error.
>
>
>
> So, I tried the following method of checking to see whether I'm dealing
>
> with all NaNs
>
>
>
> for j = 0, 9 do begin
>
> ; make one year subset of 2800x1800x12
>
> subset = array[*,*,j*12:j*12+12]
>
> if max(finite(subset)) eq 1 then begin
>
> newarray[0,0,j] = mean(newarray, dimension=3, /nan)
>
> endif else begin
>
> newarray[0,0,j] = make_array(2800,2800,value=!VALUES.D_NAN)
>
> endelse
>
> endfor
>
>
>
> This eliminates the error for any situation where the entire subset is
>
> NaN. However, because the mean function is essentially calculating
>
> 2800x2800 means of 12 elements each, there are instances where only one
>
> or a few of those 12-element sets are completely NaN, which is not
>
> caught by my method of checking, so I still get the error message.
>
>
>
> The only way I can imagine extending my checking method would be to
>
> loop through every row and column of the data set, calculating each
>
> mean one at a time so that I can check whether or not all 12 elements
>
> are NaN. Of course, that would be incredibly inefficient, so I would
>
> not seriously entertain that idea.
>
>
>
> Is there a better solution out there, or should I just suck it up and
>
> live with the error message?

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[Message index]

		avoiding "floating illegal operand" errors with /nan keyword in mean By: Paul Levine on Tue, 20 August 2013 16:37
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: wlandsman on Tue, 20 August 2013 17:26
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: Paul Levine on Tue, 20 August 2013 19:17
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: wlandsman on Wed, 21 August 2013 05:58
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: Paul Levine on Thu, 22 August 2013 12:16
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: Fabzi on Wed, 21 August 2013 14:11
		Re: avoiding "floating illegal operand" errors with /nan keyword in mean By: Paul Levine on Thu, 22 August 2013 12:26

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