Skip to main content

execfile and imported modules

I was given to believe that Python's execfile statement simply executed all the commands in a file and continued on its way. This is not entirely true, at least in Python 2.7: imported modules seem not to be handled by the execfile statement, which seems to be rather odd to me.

import numpy


def gen(n=100):
  return numpy.arange(n)

This code does what you expect when you import it as a module:

In [1]: import test

In [2]: test.gen(10)
Out[2]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

And when you run it as a script to incorporate it into your workspace:

In [3]: run test

In [4]: gen(10)
Out[4]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

However, when you use execfile to run the script you run into a snag:


In [5]: pars = {}; execfile('test.py', {}, pars); pars['gen'](10)
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-5-b06061c74d2b> in <module>()
----> 1 pars = {}; execfile('test.py', {}, pars); pars['gen'](10)
/Users/kghose/Code/Mitty/Test/test.py in gen(n)
      3 
      4 def gen(n=100):
----> 5   return numpy.arange(n)
NameError: global name 'numpy' is not defined

Whaaaaa?

If, instead, you use the fascinating standard Python imp module, you get:


In [7]: import imp; mod = imp.load_source('test','./test.py', open('test.py','r'))
In [8]: mod
Out[8]: <module 'test' from './test.pyc'>
In [9]: mod.gen(10)
Out[9]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

Things run as they should.

Comments

Popular posts from this blog

Flowing text in inkscape (Poster making)

You can flow text into arbitrary shapes in inkscape. (From a hint here).

You simply create a text box, type your text into it, create a frame with some drawing tool, select both the text box and the frame (click and shift) and then go to text->flow into frame.

UPDATE:

The omnipresent anonymous asked:
Trying to enter sentence so that text forms the number three...any ideas?
The solution:
Type '3' using the text toolConvert to path using object->pathSize as necessaryRemove fillUngroupType in actual text in new text boxSelect the text and the '3' pathFlow the text

Drawing circles using matplotlib

Use the pylab.Circle command

import pylab #Imports matplotlib and a host of other useful modules cir1 = pylab.Circle((0,0), radius=0.75, fc='y') #Creates a patch that looks like a circle (fc= face color) cir2 = pylab.Circle((.5,.5), radius=0.25, alpha =.2, fc='b') #Repeat (alpha=.2 means make it very translucent) ax = pylab.axes(aspect=1) #Creates empty axes (aspect=1 means scale things so that circles look like circles) ax.add_patch(cir1) #Grab the current axes, add the patch to it ax.add_patch(cir2) #Repeat pylab.show()

Pandas panel = collection of tables/data frames aligned by index and column

Pandas panel provides a nice way to collect related data frames together while maintaining correspondence between the index and column values:


import pandas as pd, pylab #Full dimensions of a slice of our panel index = ['1','2','3','4'] #major_index columns = ['a','b','c'] #minor_index df = pd.DataFrame(pylab.randn(4,3),columns=columns,index=index) #A full slice of the panel df2 = pd.DataFrame(pylab.randn(3,2),columns=['a','c'],index=['1','3','4']) #A partial slice df3 = pd.DataFrame(pylab.randn(2,2),columns=['a','b'],index=['2','4']) #Another partial slice df4 = pd.DataFrame(pylab.randn(2,2),columns=['d','e'],index=['5','6']) #Partial slice with a new column and index pn = pd.Panel({'A': df}) pn['B'] = df2 pn['C'] = df3 pn['D'] = df4 for key in pn.items: print pn[key] -> output …