[R] == operand

[Ben Bolker]

Renny Li wrote:
> 
> Hi,
>  
> I am trying to compare two values using "==" operand, please take a look
> of the following example (I copied ALL what I did here without deleting
> any line)
>  
>>    bb<-1
>> cc<-50
>> cc==abs(bb+52)
> [1] FALSE
>> C<-53
>> C<-53
>> c<-53
>> cc==abs(bb+52)
> [1] FALSE            
>  
> I am expecting to see a TRUE here. 
> 

Why?  You are modifying the variables C and c, but not cc.
Perhaps you are confused about the == operator, which
doesn't do assignments -- it only tests equality.


Renny Li wrote:
> 
> Then I tried another way,
>  
>> abs(1+52)
> [1] 53
>> cc==abs(1+52)
> [1] FALSE
> 
> Why it is FALSE.
> 

 Because cc is 50, which isn't equal to 53? 


Renny Li wrote:
> 
>  Then I tried
> 
> 
>> d<-abs(b+52)
> Error: object "b" not found
>> d<-abs(bb+52)
>> d
> [1] 53
>> c==d
> [1] TRUE
> 
> Now it is TRUE, 
> 

Which makes sense because c is 53 and d is 1+52 (i.e., 53)


Renny Li wrote:
> 
> but a wired thing is as following,
>> c==abs(bb+52)
> [1] TRUE
> 
> The coding "c==abs(bb+52)" is just the same from the 3line in the top, why
> 2 different results? HOWEVER, it is not repeatable, I am glad I did not
> close the window.
> 

It's different, because cc and c are different


Renny Li wrote:
> 
> Also, 
>> c<-0.5-0.1
>> n<-0.6-0.2
>> n==c
> [1] FALSE
> 

For this one, you need to see FAQ 7.31 ...


-- 
View this message in context: http://www.nabble.com/%3D%3D-operand-tp20928790p20929535.html
Sent from the R help mailing list archive at Nabble.com.