How to use the function numpy.append
append, numpy, python
Solution
Unlike the list `append` method, numpy's `append` does not append in-place. It returns a new array with the extra elements appended. So you'd need to do `r = np.append(r, float(line[index]))`.
Building up numpy arrays in this way is inefficient, though. It's better to just build your list as a Python list and then make a numpy array at the end.
Problem
I have a problem using the function numpy.append. I wrote the following function as part of a larger piece of code, however, my error is reproduced in the folowing: ``` data = [ [ '3.5', '3', '0', '0', '15', '6', '441', 'some text', 'some more complicated data' ], [ '4.5', '5', '1', '10', '165', '0', '1', 'some other text', 'some even more complicated data' ] ] def GetNumpyArrey(self, index): r = np.array([]) for line in data: np.append(r, float(line[index])) print r ``` index < 6. the result is: ``` >> [] ``` what am I doing wrong? Thanks a lot !