What is the right way to import a package?

Mon Nov 16 06:53:07 EST 2015

On 14/11/15 21:00, fl wrote:
> Hi,
>> I want to use a code snippet found on-line. It has such content:
>> from numpy import *
> dt = 0.1
> # Initialization of state matrices
> X = array([[0.0], [0.0], [0.1], [0.1]])
>> # Measurement matrices
> Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
>>>> When the above content is inside a .py document and running, there will be
> an error:
>> ---> 15 Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
> 16 #Y = ([[X[0,0]], [X[1,0] + 0]])
>> NameError: name 'randn' is not defined
>>> But when I run the above line by line at the console (Canopy), there will be
> no error for the above line.
>> My question is:
>> The import and the following are wrong.
>> X = array([[0.0], [0.0], [0.1], [0.1]])
>> It should be:
>> import numpy as np
> ...
> Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])
>> This looks like the code I once saw. But the file when running has such
> error:
>> ---> 15 Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])
>> AttributeError: 'module' object has no attribute 'randn'
>> When it is run line by line at the console, it has the same error.
>> It is strange that the same content has errors depends on inside a file, or
> at CLI console.
>> What is missing I don't realize? Thanks,
>>
You can try :
from numpy import *
from numpy.random import *
HTH,
- Grobu -