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 [[alternative HTML version deleted]]
Okay, it turns out that there were leading spaces, so that in the data, it was represented as " NaN", hence the expression =="NaN" was coming back as false. Is there a way to find out preemptively if there are leading spaces? Thanks, Andrew On 5/29/07, Andrew Yee <andrewjyee@gmail.com> wrote:> > 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 >[[alternative HTML version deleted]]
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
[[alternative HTML version deleted]]
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