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Re: How to ignore NaNs in the data array with function cgPercentile.pro or Percentile.pro? [message #90948 is a reply to message #90946]

Mon, 18 May 2015 06:36

Helder Marchetto
Messages: 520
Registered: November 2011

Senior Member

On Monday, May 18, 2015 at 3:18:53 PM UTC+2, Madhavan Bomidi wrote:
> Hello,
>
> I have two data arrays one with some missing data and the other without missing data as below:
>
> data = [Randomu(3L, 100) * 100, !Values.F_NAN, !Values.F_NaN]
>
> data1 = [Randomu(3L, 100) * 100]
>
> When I use the cgPercentiles, I don't want missing data to be included.

To avoid including NaN you could use the finite() function:
data = data[where(finite(data))]
and then calculate percentiles.d
Here is an example
data = Randomu(3L, 100) * 100
data1 = [data, !Values.F_NAN, !Values.F_NaN]
data2 = data1[where(finite(data1))]
Print, cgPercentiles(data, Percentiles=[0.25, 0.5, 0.75])
Print, cgPercentiles(data1, Percentiles=[0.25, 0.5, 0.75])
Print, cgPercentiles(data2, Percentiles=[0.25, 0.5, 0.75])
In my case, I got:
27.4920 45.3172 69.3138
27.4920 45.4608 69.4824
27.4920 45.3172 69.3138
First and last line are the same and that's what you want.
As David said, if you don't have a strategy to substitute NaNs with numbers, you can't deal with them.

Cheers,
Helder

ps: the above code will not work (or give you trouble) if your data is made out of *only* NaNs. When using the where() function you should check for how many finite numbers where found...

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[Message index]

		How to ignore NaNs in the data array with function cgPercentile.pro or Percentile.pro? By: atmospheric physics on Mon, 18 May 2015 06:18
		Re: How to ignore NaNs in the data array with function cgPercentile.pro or Percentile.pro? By: David Fanning on Mon, 18 May 2015 06:28
		Re: How to ignore NaNs in the data array with function cgPercentile.pro or Percentile.pro? By: Helder Marchetto on Mon, 18 May 2015 06:36
		Re: How to ignore NaNs in the data array with function cgPercentile.pro or Percentile.pro? By: Matthew Argall on Mon, 18 May 2015 06:44

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