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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...
What is the Python 3 equivalent of “python -m SimpleHTTPServer”
What is the Python 3 equivalent of python -m SimpleHTTPServer ?
5 Answers
5
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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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Does Python have an ordered set?
...ferred to from the Python 2 Documentation. This runs on Py2.6 or later and 3.0 or later without any modifications. The interface is almost exactly the same as a normal set, except that initialisation should be done with a list.
OrderedSet([1, 2, 3])
This is a MutableSet, so the signature for .uni...
Why do enum permissions often have 0, 1, 2, 4 values?
...are people always using enum values like 0, 1, 2, 4, 8 and not 0, 1, 2, 3, 4 ?
7 Answers
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Aggregate / summarize multiple variables per group (e.g. sum, mean)
...~ variable, sum)
# year month x1 x2
1 2000 1 -80.83405 -224.9540159
2 2000 2 -223.76331 -288.2418017
3 2000 3 -188.83930 -481.5601913
4 2000 4 -197.47797 -473.7137420
5 2000 5 -259.07928 -372.4563522
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Simple way to create matrix of random numbers
...
13 Answers
13
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How can I do an asc and desc sort using underscore.js?
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365
You can use .sortBy, it will always return an ascending list:
_.sortBy([2, 3, 1], function(nu...
How do I exchange keys with values in a dictionary?
...
Python 2:
res = dict((v,k) for k,v in a.iteritems())
Python 3 (thanks to @erik):
res = dict((v,k) for k,v in a.items())
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App Inventor 2 列表积木完全指南：从入门到精通，一篇搞定数据存储 - App...
...、布尔值（是否会员），取出来时保持原类型不变。
3. 追加列表项
使用 追加列表项 积木，将新元素添加到列表末尾。同样是块扩展积木，点击齿轮可以一次添加多项。
追加列表项 到 global colors: "黄"复制代码
三...