[R] FW: why is it numeric(0)?

[Thomas Lumley]

On Wed, 1 Jun 2005, luan_sheng wrote:

> hello,everyone. I have one question:
>
> example 1
>> x=numeric(0)
>> y=5
>> print(x+y)
> numeric(0)
>
> example 2
>> x=numeric(1)
>> y=5
>> print(x+y)
> [1] 5
>
> why the print(x+y)  is numeric(0) at the first example, but the result is 0
> at the second example?
>

numeric(0) is a zero-length vector of floating point numbers, so your 
first example takes no floating point numbers and adds 5 to each one. The 
result is still no floating point numbers.

numeric(1) is a vector containing a single 0, so the second example takes 
0 and adds 5, to give a vector containing a single 5.


 	-thomas