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Remove all occurrences of a value from a list?
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Functional approach:
Python 3.x
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter((2).__ne__, x))
[1, 3, 3, 4]
or
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter(lambda a: a != 2, x))
[1, 3, 3, 4]
Python 2.x
>>> x = [1,2...
Why does String.split need pipe delimiter to be escaped?
...this case, like with a zero-width negative assertion look behind group: (?<!\\)\| which would be line.split("(?<!\\\\)\\|");
– dlamblin
Oct 21 '15 at 23:10
add a commen...
Elegant way to invert a map in Scala
... Careful! You can loose values with this solution. For example Map(1 -> "A", 2 -> "B", 3 -> "B").map(_.swap) results in Map(A -> 1, B -> 3)
– dev-null
Apr 4 '19 at 14:06
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Convert hex to binary
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@Dragon myhex = '1A' bin(int(myhex, 16))[2:].zfill(8) >>> '00011010' zhex = '00' bin(int(zhex, 16))[2:].zfill(8) >>> '00000000' It appears that this works even when the hex string is '00'.
– DeanM
Jul 15 '19 at 15:54
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Why does my application spend 24% of its life doing a null check?
... line of code. The code for the binary tree iterator is below with the results from running performance analysis against it.
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How to get first element in a list of tuples?
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>>> a = [(1, u'abc'), (2, u'def')]
>>> [i[0] for i in a]
[1, 2]
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Format numbers to strings in Python
...seconds = 6, 56, 33
f'{hours:02}:{minutes:02}:{seconds:02} {"pm" if hours > 12 else "am"}'
or the str.format function starting with 2.7:
"{:02}:{:02}:{:02} {}".format(hours, minutes, seconds, "pm" if hours > 12 else "am")
or the string formatting % operator for even older versions of Pyth...
Passing a String by Reference in Java?
... Just keep in mind that StringBuilder is not thread safe. In multithreaded environment use the StringBuffer class or manually take care of synchronization.
– Boris Pavlović
Aug 13 '09 at 8:59
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Create an empty list in python with certain size
...nment notation if you were using a dictionary).
Creating an empty list:
>>> l = [None] * 10
>>> l
[None, None, None, None, None, None, None, None, None, None]
Assigning a value to an existing element of the above list:
>>> l[1] = 5
>>> l
[None, 5, None, None,...
Yii2 data provider default sorting
...ata\Sort object:
$dataProvider = new ActiveDataProvider([
'query' => $query,
'sort'=> ['defaultOrder' => ['topic_order' => SORT_ASC]],
]);
Official doc link
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