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Why are Python lambdas useful? [closed]
I'm trying to figure out Python lambdas. Is lambda one of those "interesting" language items that in real life should be forgotten?
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How to open a file using the open with statement
I'm looking at how to do file input and output in Python. I've written the following code to read a list of names (one per line) from a file into another file while checking a name against the names in the file and appending text to the occurrences in the file. The code works. Could it be done bette...
How to call an external command?
...if I'd typed it at the Unix shell or Windows command prompt) from within a Python script?
62 Answers
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Create a “with” block on several context managers? [duplicate]
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In Python 2.7 and 3.1 and above, you can write:
with A() as X, B() as Y, C() as Z:
do_something()
This is normally the best method to use, but if you have an unknown-length list of context managers you'll need one of the ...
Write to UTF-8 file in Python
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Read the following: http://docs.python.org/library/codecs.html#module-encodings.utf_8_sig
Do this
with codecs.open("test_output", "w", "utf-8-sig") as temp:
temp.write("hi mom\n")
temp.write(u"This has ♭")
The resulting file is UTF-8 with the...
Relative imports in Python 2.7
...short version is that there is a big difference between directly running a Python file, and importing that file from somewhere else. Just knowing what directory a file is in does not determine what package Python thinks it is in. That depends, additionally, on how you load the file into Python (by...
Print a string as hex bytes?
I have this string: Hello world !! and I want to print it using Python as 48:65:6c:6c:6f:20:77:6f:72:6c:64:20:21:21 .
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Python `if x is not None` or `if not x is None`?
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There's no performance difference, as they compile to the same bytecode:
Python 2.6.2 (r262:71600, Apr 15 2009, 07:20:39)
>>> import dis
>>> def f(x):
... return x is not None
...
>>> dis.dis(f)
2 0 LOAD_FAST 0 (x)
3 LOAD_CONST...
Reverse a string in Python
There is no built in reverse function for Python's str object. What is the best way of implementing this method?
28 Ans...
SQL DROP TABLE foreign key constraint
...llowed by the tables themselves, using a concatenation trick involving FOR XML PATH('') which allows merging multiple input rows into a single output row. Should work on anything SQL 2005 & later.
I've left the EXECUTE commands commented out for safety.
DECLARE @SQL NVARCHAR(max)
;WITH fkeys...