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Why prefer two's complement over sign-and-magnitude for signed numbers?
I'm just curious if there's a reason why in order to represent -1 in binary, two's complement is used: flipping the bits and adding 1?
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Java synchronized static methods: lock on object or class
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129
Since a static method has no associated object, will the synchronized keyword lock on the ...
Remove duplicated rows using dplyr
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139
Note: dplyr now contains the distinct function for this purpose.
Original answer below:
li...
How can I verify if one list is a subset of another?
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15 Answers
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How to determine the number of days in a month in SQL Server?
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116
You can use the following with the first day of the specified month:
datediff(day, @date, dat...
Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
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13 Answers
13
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Convert columns to string in Pandas
...will convert keys to valid json (and therefore your keys to strings):
In [11]: df = pd.DataFrame([['A', 2], ['A', 4], ['B', 6]])
In [12]: df.to_json()
Out[12]: '{"0":{"0":"A","1":"A","2":"B"},"1":{"0":2,"1":4,"2":6}}'
In [13]: df[0].to_json()
Out[13]: '{"0":"A","1":"A","2":"B"}'
Note: you can p...
Code Golf: Lasers
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Perl, 166 160 characters
Perl, 251 248 246 222 214 208 203 201 193 190 180 176 173 170 166 --> 160 chars.
Solution had 166 strokes when this contest ended, but A. Rex has found a couple ways to shave off 6 more characters:
s...