Python short course: Generator in Python

We use 'yield' to build a generator which generates values. A simple example is below.

  


In [1]: def gen_squares(N):
   ...:     """This is a example to generate values with yield"""
   ...:     for i in range(N):
   ...:         yield i**2
   ...: 

In [2]: for i in gen_squares(5):
   ...:     print(i, end=' : ')
   ...: 
0 : 1 : 4 : 9 : 16 : 
In [3]: x = gen_squares(5)

In [4]: x
Out[4]: <generator object gen_squares at 0x7f2978fff5f0>

In [5]: next(x)
Out[5]: 0

In [6]: next(x)
Out[6]: 1

In [7]: next(x)
Out[7]: 4

In [8]: next(x)
Out[8]: 9

In [9]: next(x)
Out[9]: 16

In [10]: next(x)
---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
<ipython-input-10-92de4e9f6b1e> in <module>
----> 1 next(x)

StopIteration:

Reference:

Lutz, M. Learning Python (5th ed.) O'Reilly, 2013, 1594

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