I am creating new references to the same object, instead of new objects

Question

I'm not showing the whole class as the problem is difficult to make simple, but the following is key I believe:

class helper:
    sharex = False
    sharey = False

    _objects = []

    _figures = []
    _axes = []


    def __init__(self):
        pass

    def create(self):
        figure, axes = plt.subplots(nrows=self.nrows,
                                 ncols=self.ncols,
                                 sharex=self.sharex,
                                 sharey=self.sharey)
        self._figures.append(figure)
        self._axes.append(axes)

The following should illustrate my problem:

test = plotting.helper()
test._axes
Out[9]: []
test.create()
test._axes
Out[10]: 
[array([<matplotlib.axes._subplots.AxesSubplot object at 0x103dd1940>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x10c4a5278>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x10c1889b0>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c52eeb8>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c56f4a8>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c5b7be0>], dtype=object)]
test2 = plotting.helper()
test2._axes
Out[11]: 
[array([<matplotlib.axes._subplots.AxesSubplot object at 0x103dd1940>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x10c4a5278>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x10c1889b0>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c52eeb8>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c56f4a8>,
        <matplotlib.axes._subplots.AxesSubplot object at 0x11c5b7be0>], dtype=object)]

The second object should be created empty, and without any axes stored in _axes. Yet, not only does it contain axes, it's the same axes as the (supposedly) independent other object.

Why am I not creating independent objects?

I would recommend you read a Python OOP tutorial, which will explain much of this. — jonrsharpe, Oct 22 '16 at 09:51

score 0 · Answer 1 · answered Oct 22 '16 at 09:52

0

When you declare _axes in the class declaration, you make it a static variable, means it is mutual to all instances. You want to move the declaration of _axes to the __init__ function.

answered Oct 22 '16 at 09:52

Sawel

929
7
17

The question has already been marked as a dupe. – Padraic Cunningham Oct 22 '16 at 09:54
Yes I see it now... Didn't notify me in the mobile app. – Sawel Oct 22 '16 at 09:56

I am creating new references to the same object, instead of new objects

1 Answers1