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What is the difference between JOIN and UNION?
...mpletely different operations. Trivial example of UNION:
mysql> SELECT 23 AS bah
-> UNION
-> SELECT 45 AS bah;
+-----+
| bah |
+-----+
| 23 |
| 45 |
+-----+
2 rows in set (0.00 sec)
similary trivial example of JOIN:
mysql> SELECT * FROM
-> (SELECT 23 AS bah) AS fo...
How to initialize a dict with keys from a list and empty value in Python?
...
dict.fromkeys([1, 2, 3, 4])
This is actually a classmethod, so it works for dict-subclasses (like collections.defaultdict) as well. The optional second argument specifies the value to use for the keys (defaults to None.)
...
How do I find if a string starts with another string in Ruby?
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263
puts 'abcdefg'.start_with?('abc') #=> true
[edit] This is something I didn't know before...
How to sort in-place using the merge sort algorithm?
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142
Knuth left this as an exercise (Vol 3, 5.2.5). There do exist in-place merge sorts. They must be...
Pandas DataFrame Groupby two columns and get counts
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126
Followed by @Andy's answer, you can do following to solve your second question:
In [56]: df.gr...
do { … } while (0) — what is it good for? [duplicate]
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edited Nov 3 '08 at 9:24
answered Nov 2 '08 at 21:40
Gr...
How to remove all leading zeroes in a string
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answered Feb 23 '11 at 23:36
lonesomedaylonesomeday
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Error :: duplicate files during packaging of APK
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answered Mar 18 '14 at 5:25
Xavier DucrohetXavier Ducrohet
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What's the best way to parse command line arguments? [closed]
...ggests optparse which is appropriate for older Python versions. For Python 2.7 and above, argparse replaces optparse. See this answer for more information.
As other people pointed out, you are better off going with optparse over getopt. getopt is pretty much a one-to-one mapping of the standard ge...
Grep for literal strings
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answered Jul 14 '10 at 2:08
Scott StaffordScott Stafford
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