PyCharm - Auto Completion for matplotlib (and other imported modules)

Question

I am using PyCharm 2016.1 and Python 2.7 on Windows 10 and imported the matplotlib module.

As the matplotlib module ist very extensive and I am relatively new to Python, I hoped the Auto Complete function in PyCharm could help me to get an overview of the existent properties/ functions of an object. It would be more convenient as digging through the api documentation every time, not knowing what to look for an where to find it.

For example:

from matplotlib import pyplot as plt
fig, ax = plt.subplots()

When I type ax. there ist no auto completion for the properties, functions etc. of the axis, I only get the suggestions list.

I already tried this and imported the axis module directly with:

import matplotlib.axis as axis

or

from matplotlib.axis import Axis as axis

Smart Auto Completion and 'Collect run-time types information' is already enabled.

Is there a way to enable the auto completion like described or is there another IDE that supports that?

Answer 1

In addition to Paul's answer. If you are using fig, ax = plt.subplots() , you could use figure type hint. See below example:

from matplotlib import pyplot as plt
import matplotlib.axes._axes as axes
import matplotlib.figure as figure

fig, ax = plt.subplots()  # type:figure.Figure, axes.Axes
ax.
fig.

Answer 2

I believe your problem is highlighted here:

https://intellij-support.jetbrains.com/hc/en-us/community/posts/205816499-Improving-collecting-run-time-type-information-for-code-insight?sort_by=votes

Tldr return types can vary, so it cant be figured out at compile time.

Most accepted way is to use a type hint, since it can only figure out what type it as run time :

import matplotlib.axes._axes as axes

fig = plt.figure(figsize=(5,10))
ax1 = fig.add_subplot(3,1,1) # type:axes.Axes
ax1.set_xlabel('Test') <- now autocompletes

You can also try an assert isinstance:

import matplotlib.axes._axes as axes

fig = plt.figure(figsize=(5,10))
ax1 = fig.add_subplot(3,1,1)
assert isinstance(ax1, axes.Axes)
ax1.set_xlabel('Test')

It wont find the autocomplete if you do it after the method you are looking for:

ax1.set_xlabel('Test')
assert isinstance(ax1, axes.Axes)

With this, you shouldnt let isinstance dictate the control flow of your code, if you are trying to run a method that doesnt exist on an object, it should crash, however, if your different object has a method of the same name (!) then you have inadvertently reached that goal without annotations being there. So I like it better, since you want it to crash early and in the correct place. YMMV

From the doc:

Assertions should not be used to test for failure cases that can occur because of bad user input or operating system/environment failures, such as a file not being found. Instead, you should raise an exception, or print an error message, or whatever is appropriate. One important reason why assertions should only be used for self-tests of the program is that assertions can be disabled at compile time.

If Python is started with the -O option, then assertions will be stripped out and not evaluated. So if code uses assertions heavily, but is performance-critical, then there is a system for turning them off in release builds. (But don't do this unless it's really necessary.

https://wiki.python.org/moin/UsingAssertionsEffectively

Alternatively, if you dont want to add to your code in this fashion, and have Ipython/jupyter installed through anoconda, you can get the code completion from the console by right clicking the code to be ran and choosing "execute selection in console"