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How to filter a dictionary according to an arbitrary condition function?
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434
Nowadays, in Python 2.7 and up, you can use a dict comprehension:
{k: v for k, v in points.ite...
PHP append one array to another (not array_push or +)
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436
array_merge is the elegant way:
$a = array('a', 'b');
$b = array('c', 'd');
$merge = array_mer...
Cost of len() function
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360
It's O(1) (constant time, not depending of actual length of the element - very fast) on every ...
using awk with column value conditions
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132
If you're looking for a particular string, put quotes around it:
awk '$1 == "findtext" {print ...
How to count the number of occurrences of an element in a List
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341
I'm pretty sure the static frequency-method in Collections would come in handy here:
int occu...
How can I convert a dictionary into a list of tuples?
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363
>>> d = { 'a': 1, 'b': 2, 'c': 3 }
>>> d.items()
[('a', 1), ('c', 3), ('b', ...
Change the name of a key in dictionary
...elete dictionary[old_key].
>>> dictionary = { 1: 'one', 2:'two', 3:'three' }
>>> dictionary['ONE'] = dictionary.pop(1)
>>> dictionary
{2: 'two', 3: 'three', 'ONE': 'one'}
>>> dictionary['ONE'] = dictionary.pop(1)
Traceback (most recent call last):
File "<inp...
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
I have a dataframe with ~300K rows and ~40 columns.
I want to find out if any rows contain null values - and put these 'null'-rows into a separate dataframe so that I could explore them easily.
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get list from pandas dataframe column
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534
Pandas DataFrame columns are Pandas Series when you pull them out, which you can then call x.to...
How to profile a bash shell script slow startup?
My bash shell takes up to 3-4 seconds to start up, while if I start it with --norc it runs immediately.
7 Answers
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