One-Liners
In this chapter I will show you some one-liner Python commands which can be really helpful.
Simple Web Server
Ever wanted to quickly share a file over a network? Well you are in luck. Python has a feature just for you. Go to the directory which you want to serve over the network and write the following code in your terminal:
# Python 2 python -m SimpleHTTPServer # Python 3 python -m http.server
Pretty Printing
You can print a list and dictionary in a beautiful format in the Python repl. Here is the relevant code:
from pprint import pprint my_dict = {'name': 'Yasoob', 'age': 'undefined', 'personality': 'awesome'} print(dir(my_dict)) # ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort'] pprint(dir(my_dict)) # ['__add__', # '__class__', # '__contains__', # '__delattr__', # '__delitem__', # '__dir__', # '__doc__', # '__eq__', # '__format__', # '__ge__', # '__getattribute__', # '__getitem__', # '__gt__', # '__hash__', # '__iadd__', # '__imul__', # '__init__', # '__init_subclass__', # '__iter__', # '__le__', # '__len__', # '__lt__', # '__mul__', # '__ne__', # '__new__', # '__reduce__', # '__reduce_ex__', # '__repr__', # '__reversed__', # '__rmul__', # '__setattr__', # '__setitem__', # '__sizeof__', # '__str__', # '__subclasshook__', # 'append', # 'clear', # 'copy', # 'count', # 'extend', # 'index', # 'insert', # 'pop', # 'remove', # 'reverse', # 'sort']
This is more effective on nested dict s. Moreover, if you want to pretty print
json quickly from a file then you can simply do:
cat file.json | python -m json.tool
Profiling a script
This can be extremely helpful in pinpointing the bottlenecks in your scripts:
python -m cProfile my_script.py
Note: cProfile is a faster implementation of profile as it is
written in c
CSV to json
Run this in the terminal:
python -c "import csv,json;print json.dumps(list(csv.reader(open('csv_file.csv'))))"
Make sure that you replace csv_file.csv to the relevant file name.
List Flattening
You can quickly and easily flatten a list using
itertools.chain.from_iterable from the itertools package. Here
is a simple example:
a_list = [[1, 2], [3, 4], [5, 6]] print(list(itertools.chain.from_iterable(a_list))) # Output: [1, 2, 3, 4, 5, 6] # or print(list(itertools.chain(*a_list))) # Output: [1, 2, 3, 4, 5, 6]
One-Line Constructors
Avoid a lot of boilerplate assignments when initializing a class
class A(object): def __init__(self, a, b, c, d, e, f): self.__dict__.update({k: v for k, v in locals().items() if k != 'self'})
Additional one-liners can be found on the Python website.