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Different ways of clearing lists
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362
Clearing a list in place will affect all other references of the same list.
For example, this...
Find MongoDB records where array field is not empty
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873
If you also have documents that don't have the key, you can use:
ME.find({ pictures: { $exists:...
How to re-raise an exception in nested try/except blocks?
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132
As of Python 3 the traceback is stored in the exception, so a simple raise e will do the (mostl...
Display a float with two decimal places in Python
...uld use the string formatting operator for that:
>>> '%.2f' % 1.234
'1.23'
>>> '%.2f' % 5.0
'5.00'
The result of the operator is a string, so you can store it in a variable, print etc.
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Is a Python list guaranteed to have its elements stay in the order they are inserted in?
...nd places it behind the content of another.
If we have
list1 = [0, 1, 2, 3, 4]
list2 = [5, 6, 7, 8, 9]
Then
list1 + list2
Is the same as
[0, 1, 2, 3, 4] + [5, 6, 7, 8, 9]
Which evaluates to
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Much like
"abdcde" + "fghijk"
Produces
"abdcdefghijk"
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Using a dictionary to count the items in a list [duplicate]
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in 2.7 and 3.1 there is special Counter dict for this purpose.
>>> from collections import Counter
>>> Counter(['apple','red','apple','red','red','pear'])
Counter({'red': 3, 'apple': 2, 'pear': 1})
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Java 8 stream reverse order
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edited Jan 29 '16 at 18:31
answered Jun 3 '14 at 9:13
Stu...
Find the nth occurrence of substring in a string
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3
Thanks, I like your one liner. I don't think it's the most instantly readable thing in the world, but it's not much worse then most others b...
Try-finally block prevents StackOverflowError
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332
It doesn't run forever. Each stack overflow causes the code to move to the finally block. The ...
case-insensitive list sorting, without lowercasing the result?
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In Python 3.3+ there is the str.casefold method that's specifically designed for caseless matching:
sorted_list = sorted(unsorted_list, key=str.casefold)
In Python 2 use lower():
sorted_list = sorted(unsorted_list, key=lambda s: s....