[Tutor] problem editing modules and defs

[David Craig]

Hi again, sorry if that wasnt clear. I am using the ipython interpreter 
to debug scripts. I have a function:-) saved as part of a module called 
daves_modules.py.

    import numpy as np
    def find_nearest(array,value):

         idx=(np.abs(array-value)).argmin()
         return array[idx], idx


If I run the module from the interpreter as follows,


    In [610]: %run daves_modules.py

    In [611]: a = find_nearest(pos_time, highTime)

    In [612]: a
    Out[612]: (20.009998091697867, 200)


it works fine. However, if I use the same function in a script like this,

    import numpy as np
    import pylab as py
    from daves_modules import dist, find_nearest
    .
    .
    .
    a = find_nearest(pos_time, highTime)


I get the following error,

    %run SNR_UFAN_UCRUI.py
    ---------------------------------------------------------------------------
    IndexError                                Traceback (most recent
    call last)

    /home/davcra/python_scripts/SNR_UFAN_UCRUI.py in <module>()
          88 b = find_nearest(pos_time, lowTime)
          89
    ---> 90 pos_noise =
    (np.sum(pos_signal[0:a[1]])+np.sum(pos_signal[b[1]:-1])) / (a[1] +
    (len(pos_signal)-b[1]))
          91 neg_noise =
    (np.sum(neg_signal[0:-a[1]])+np.sum(neg_signal[-b[1]:-1])) / (a[1] +
    (len(neg_signal)-b[1]))
          92

    IndexError: invalid index to scalar variable.
    WARNING: Failure executing file: <SNR_UFAN_UCRUI.py>


If I then try to use the function in ipython again,

    In [614]: a = find_nearest(pos_time, highTime)

    In [615]: a
    Out[615]: 20.009998091697867


Note: the function originally only returned array[idx], so it seems to 
have reverted to this somehow.





On 02/24/2012 04:28 PM, Evert Rol wrote:
>    Hi David,
>
>> Hi,
>> I am new to python and have made a couple of definitions. I imported them and they worked ok. I they worked except for one which gave me the error "NameError: global name 'np' is not defined". I then edited my script for the def to include "import numpy as np" saved it and imported the def again. However, it still gives me the same error. I know I have to be doing something basic wrong but cant figure it out, anyone know what I am doing wrong. The def is below.
>> thanks
> Minor thing first: in Python terminology, most of the time your 'definitions' are simply called functions, although you're correct that "def" refers to definition. But thatt's more about where the function is defined, in contrast to where in the code it is called (or perhaps even declared, though I don't think that applies to Python).
>
>
> When you say "I imported the def again", it sounds like you're working on the Python interpreter, and doing
>>>> import myscript
> or similar.
> If that's how you run things, you would have to use the reload() function to reload the new function definition, which has your correction.
>
> However, you also talk about 'my script'. A script is something I would run from the shell command line, like
> $>  python myscript.py
>
> If you do things that way, you would always be ensured that python uses the latest edits in your script.
> It does mean that any command you would normally type into the Python interpreter, you would now have to enter in the script. And while the interpreter always shows the evaluation result of the last command entered, a script would require a print for that. Compare:
>>>> a=1
>>>> a
> 1
>
> versus (inside a script):
> a = 1
> a  # this doesn't show anything
> print a  # this does
>
> Perhaps this is too basic, but I have to guess a bit what you are doing from your text.
>
> A few tips to get more practical help:
> - Python normally shows a stack trace when there is an error. It is good to copy-paste the whole thing in your emails. Just typing the last bit often doesn't help.
> - Copy-paste (again, don't type) whatever you're doing in the Python interpreter, if that's what you are using. So we can how you do things (examples are clearer than descriptions). If needs be, intersperse with comments.
> Compare eg:
>>>> import myscript
> NameError: global name 'np' is not defined".
>>>> # editing myscript.py
>>>> import myscript
> NameError: global name 'np' is not defined".
>
> And we can immediately see you don't reload() the script.
>
> Hope this gets you further.
>
> Have fun,
>
>    Evert
>
>
>
>> D
>>
>> import numpy as np
>>
>> def find_nearest(array,value):
>>     idx=(np.abs(array-value)).argmin()
>>     return array[idx]
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