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Get the first element of each tuple in a list in Python [duplicate]
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Use a list comprehension:
res_list = [x[0] for x in rows]
Below is a demonstration:
>>> rows = [(1, 2), (3, 4), (5, 6)]
>>> [x[0] for x in rows]
[1, 3, 5]
>>>
Alternately, you could use unpacking instead of x[0]:
res_list = [x for x,...
Importing a CSV file into a sqlite3 database table using Python
...` statement available in 2.5+
# csv.DictReader uses first line in file for column headings by default
dr = csv.DictReader(fin) # comma is default delimiter
to_db = [(i['col1'], i['col2']) for i in dr]
cur.executemany("INSERT INTO t (col1, col2) VALUES (?, ?);", to_db)
con.commit()
con.c...
Python list directory, subdirectory, and files
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Use os.path.join to concatenate the directory and file name:
for path, subdirs, files in os.walk(root):
for name in files:
print os.path.join(path, name)
Note the usage of path and not root in the concatenation, since using root would be incorrect.
In Python 3.4, the path...
JavaScript is in array
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This doesn't work for old browsers (like IE < 9). There's a jQuery function for this: api.jquery.com/jQuery.inArray
– Vinicius Pinto
Oct 5 '12 at 14:42
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Get a random boolean in python?
I am looking for the best way (fast and elegant) to get a random boolean in python (flip a coin).
8 Answers
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Django in / not in query
I'm trying to figure out how to write a 'not in' style query in django.
For example, the query structure I'm thinking of would look like this.
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How to implement an STL-style iterator and avoid common pitfalls?
I made a collection for which I want to provide an STL-style, random-access iterator. I was searching around for an example implementation of an iterator but I didn't find any. I know about the need for const overloads of [] and * operators. What are the requirements for an iterator to be "STL-s...
urlencode vs rawurlencode?
...he one exception is legacy systems which expect the query string to follow form-encoding style of spaces encoded as + instead of %20 (in which case you need urlencode).
rawurlencode follows RFC 1738 prior to PHP 5.3.0 and RFC 3986 afterwards (see http://us2.php.net/manual/en/function.rawurlencode.p...
Adjust UILabel height to text
... which I want to adjust their height to the text, this is the code I wrote for this now
17 Answers
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Why does changing 0.1f to 0 slow down performance by 10x?
...me to the world of denormalized floating-point! They can wreak havoc on performance!!!
Denormal (or subnormal) numbers are kind of a hack to get some extra values very close to zero out of the floating point representation. Operations on denormalized floating-point can be tens to hundreds of times ...