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Why do I get TypeError: can't multiply sequence by non-int of type 'float'?
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raw_input returns a string (a sequence of characters). In Python, multiplying a string and a float makes no defined meaning (while multiplying a string and an integer has a meaning: "AB" * 3 is "ABABAB"; how much is "L" * 3.14 ? Please do not reply "LLL|"). You need to parse the str...
How can strings be concatenated?
How to concatenate strings in python?
7 Answers
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Add up a column of numbers at the Unix shell
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python3 -c"import os; print(sum(os.path.getsize(f) for f in open('files.txt').read().split()))"
Or if you just want to sum the numbers, pipe into:
python3 -c"import sys; print(sum(int(x) for x in sys.stdin))"
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Why use argparse rather than optparse?
I noticed that the Python 2.7 documentation includes yet another command-line parsing module. In addition to getopt and optparse we now have argparse .
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what does the __file__ variable mean/do?
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When a module is loaded from a file in Python, __file__ is set to its path. You can then use that with other functions to find the directory that the file is located in.
Taking your examples one at a time:
A = os.path.join(os.path.dirname(__file__), '..')
# A is...
How Pony (ORM) does its tricks?
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Pony ORM author is here.
Pony translates Python generator into SQL query in three steps:
Decompiling of generator bytecode and rebuilding generator AST
(abstract syntax tree)
Translation of Python AST into "abstract SQL" -- universal
list-based representation of a...
Filter dict to contain only certain keys?
...Uses dictionary comprehension.
If you use a version which lacks them (ie Python 2.6 and earlier), make it dict((your_key, old_dict[your_key]) for ...). It's the same, though uglier.
Note that this, unlike jnnnnn's version, has stable performance (depends only on number of your_keys) for old_dicts...
How to get POSTed JSON in Flask?
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For reference, here's complete code for how to send json from a Python client:
import requests
res = requests.post('http://localhost:5000/api/add_message/1234', json={"mytext":"lalala"})
if res.ok:
print res.json()
The "json=" input will automatically set the content-type, as discu...
Using .sort with PyMongo
...is that the ordering of the arguments matters and dicts are not ordered in Python < 3.6
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Multiple levels of 'collection.defaultdict' in Python
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This is awesome. It seems I renew my marital vows to Python daily.
– mVChr
Nov 3 '14 at 22:32
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