data is a Python dictionary. It needs to be encoded as JSON before writing. Use this for maximum compatibility (Python 2 and 3): import json with open(‘data.json’, ‘w’) as f: json.dump(data, f) On a modern system (i.e. Python 3 and UTF-8 support), you can write a nicer file using: import json with open(‘data.json’, ‘w’, encoding=’utf-8′) … Read more
>>> str(42) ’42’ >>> int(’42’) 42 Links to the documentation: int() str() str(x) converts any object x to a string by calling x.__str__().
This works for everyone: pip install -r /path/to/requirements.txt Explanation: -r, –requirement < filename > Install from the given requirements file. This option can be used multiple times.
When using matplotlib.pyplot.savefig, the file format can be specified by the extension: from matplotlib import pyplot as plt plt.savefig(‘foo.png’) plt.savefig(‘foo.pdf’) That gives a rasterized or vectorized output respectively. In addition, there is sometimes undesirable whitespace around the image, which can be removed with: plt.savefig(‘foo.png’, bbox_inches=”tight”) Note that if showing the plot, plt.show() should follow plt.savefig(); … Read more
From the docs: The SimpleHTTPServer module has been merged into http.server in Python 3.0. The 2to3 tool will automatically adapt imports when converting your sources to 3.0. So, your command is python -m http.server, or depending on your installation, it can be: python3 -m http.server
Using slicing: >>> ‘hello world'[::-1] ‘dlrow olleh’ Slice notation takes the form [start:stop:step]. In this case, we omit the start and stop positions since we want the whole string. We also use step = -1, which means, “repeatedly step from right to left by 1 character”.
Python includes a profiler called cProfile. It not only gives the total running time, but also times each function separately, and tells you how many times each function was called, making it easy to determine where you should make optimizations. You can call it from within your code, or from the interpreter, like this: import … Read more
Is there any reason for a class declaration to inherit from object? In Python 3, apart from compatibility between Python 2 and 3, no reason. In Python 2, many reasons. Python 2.x story: In Python 2.x (from 2.2 onwards) there’s two styles of classes depending on the presence or absence of object as a base-class: … Read more
The column names (which are strings) cannot be sliced in the manner you tried. Here you have a couple of options. If you know from context which variables you want to slice out, you can just return a view of only those columns by passing a list into the __getitem__ syntax (the []’s). df1 = … Read more
For Python 3.5+ use (docs): import importlib.util import sys spec = importlib.util.spec_from_file_location(“module.name”, “/path/to/file.py”) foo = importlib.util.module_from_spec(spec) sys.modules[“module.name”] = foo spec.loader.exec_module(foo) foo.MyClass() For Python 3.3 and 3.4 use: from importlib.machinery import SourceFileLoader foo = SourceFileLoader(“module.name”, “/path/to/file.py”).load_module() foo.MyClass() (Although this has been deprecated in Python 3.4.) For Python 2 use: import imp foo = imp.load_source(‘module.name’, ‘/path/to/file.py’) foo.MyClass() … Read more