Re: [R] trouble understanding why ...=="NaN" isn't true

From: Bert Gunter <gunter.berton_at_gene.com>
Date: Tue, 29 May 2007 15:39:58 -0700

  1. "NaN" is a character string, **not** NaN; hence is.nan("NaN") yields FALSE.
  2. Please read the docs! ?NaN explicitly says:

"Do not test equality to NaN, or even use identical, since systems typically have many different NaN values."

Bert Gunter
Genentech Nonclinical Statistics

-----Original Message-----
From: r-help-bounces_at_stat.math.ethz.ch
[mailto:r-help-bounces_at_stat.math.ethz.ch] On Behalf Of Andrew Yee Sent: Tuesday, May 29, 2007 3:33 PM
To: r-help_at_stat.math.ethz.ch
Subject: [R] trouble understanding why ...=="NaN" isn't true

I have the following data:

> dataset[2,"Sample.227"]

[1] NaN
1558 Levels: -0.000 -0.001 -0.002 -0.003 -0.004 -0.005 -0.006 -0.007 -0.008- 0.009 ... 2.000

However, I'm not sure why this expression is coming back as FALSE:

> dataset[2,"Sample.227"]=="NaN"

[1] FALSE Similarly:

> dataset[2,"Sample.227"]==NaN

[1] NA

It seems that since "NaN" is represented as a character, this expression =="NaN" should be TRUE, but it's returning as FALSE.

Thanks,
Andrew

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 29 May 2007 - 22:45:47 GMT

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