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

[Sundar Dorai-Raj]

Hi, Andrew,

Looks like you're reading the data incorrectly. If using ?read.table or 
the like, try to add a na.strings = c("NA", "NaN") argument. Second, 
Bert's comment: use ?is.nan, rather than "==".

--sundar

Andrew Yee said the following on 5/29/2007 3:39 PM:
> 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 at 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
>>
> 
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