[SciPy-user] what different between array([ 1., 2., 3.]) and array([[ 1., 2., 3.]])

Zhang Sam hollowspook at gmail.com
Mon Nov 27 06:31:17 CST 2006


Hi, there

I am a newer here. I just used numpy and scipy for a while.
I am confused about the 1-D array.

The code is as follows:
---------------------------------------------------------------------------------------------------
>>> x=array([1 ,2.,3])
>>> x
array([ 1.,  2.,  3.])
>>> x.shape
(3,)
>>> x[0,:]
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
IndexError: too many indices
>>> x.shape = 1,3
>>> x
array([[ 1.,  2.,  3.]])
>>> x[0,:]
array([ 1.,  2.,  3.])
-----------------------------------------------------------------------------------------------------

Typing x=array([1 ,2.,3])  will generate array([ 1.,  2.,  3.]). Since this
is a array variable, It should be indexd by list. However  x[0,:] is wrong.
I must force its shape to (1,3), then x[0,:] will return a array.

Both x (before and after) is array class. Why the indexing method exist
difference.
What's difference between them?

If there is explaination in some document already, a link to it is ok.
Please do me a favour.


Thanks in advance.
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