title: How to check python codes by reduction?
body: <pre><code>import numpy
  def rtpairs(R,T):
      for i in range(numpy.size(R)):
          o=0.0
          for j in range(T[i]):
              o +=2*(numpy.pi)/T[i]
              yield R[i],o
  R=[0.0,0.1,0.2]
  T=[1,10,20]
  for r,t in genpolar.rtpairs(R,T):
  plot(r*cos(t),r*sin(t),'bo')
  </code></pre>
  
  <p>This program is supposed to be a generator, but I would like to check if i'm doing the right thing by first asking it to return some values for pheta (see below)</p>
  
  <pre><code>import numpy as np
  def rtpairs (R=None,T=None):
      R = np.array(R)
      T = np.array(T)
      for i in range(np.size(R)):
          pheta = 0.0   
          for j in range(T[i]):
              pheta += (2*np.pi)/T[i]
              return pheta
  </code></pre>
  
  <p>Then 
  I typed import omg as o in the prompt</p>
  
  <pre><code>x = [o.rtpairs(R=[0.0,0.1,0.2],T=[1,10,20])]
  # I tried to collect all values generated by the loops
  </code></pre>
  
  <p>It turns out to give me only one value which is 2 pi ... I have a habit to check my codes in the half way through, Is there any way for me to get a list of angles by using the code above? I don't understand why I must use a generator structure to check (first one) , but I couldn't use normal loop method to check.</p>
  
  <p>Normal loop e.g. </p>
  
  <pre><code>x=[i for i in range(10)]
  x=[0,1,2,3,4,5,6,7,8,9]
  </code></pre>
  
  <p>Here I can see a list of values I should get. </p>