AttributeError: 'numpy.ndarray' object has no attribute 'append'

I am trying to run the code presented on the second page:

http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00-introduction-to-computer-science-and-programming-fall-2008/video-lectures/lecture-20/lec20.pdf

At the bottom of the code you have to add these lines:

simFlips(100,100)

show()

Here is the error that I get when I run it on ubuntu:

Traceback (most recent call last):
  File "coin.py", line 36, in <module>
    simFlips(100,100)
  File "coin.py", line 16, in simFlips
    diffs.append(abs(heads - tails))
AttributeError: 'numpy.ndarray' object has no attribute 'append'

Please tell me what I'm doing wrong that gives me the last error. Thanks in advance!

Use numpy.concatenate(list1 , list2) or numpy.append() Look into the thread at https://stackoverflow.com/questions/9775297/append-a-numpy-array-to-a-numpy-array.

I got this error after change a loop in my program, let`s see:

for ...
  for ... 
     x_batch.append(one_hot(int_word, vocab_size))
     y_batch.append(one_hot(int_nb, vocab_size, value))
  ...
  ...
  if ...
        x_batch = np.asarray(x_batch)
        y_batch = np.asarray(y_batch)
...

In fact, I was reusing the variable and forgot to reset them inside the external loop, like the comment of John Lyon:

for ...
  x_batch = []
  y_batch = []
  for ... 
     x_batch.append(one_hot(int_word, vocab_size))
     y_batch.append(one_hot(int_nb, vocab_size, value))
  ...
  ...
  if ...
        x_batch = np.asarray(x_batch)
        y_batch = np.asarray(y_batch)
...

Then, check if you are using np.asarray() or something like that.

You will have to use numpy function to append numpy arrays. Append will workk only for ordinary lists not numpy arrays.