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Installing specific package versions with pip
I'm trying to install version 1.2.2 of the MySQL_python adaptor, using a fresh virtualenv created with the --no-site-packages option. The current version shown in PyPi is 1.2.3 . Is there a way to install the older version? I found an article stating that this should do it:
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How can I delete one element from an array by value
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I think I've figured it out:
a = [3, 2, 4, 6, 3, 8]
a.delete(3)
#=> 3
a
#=> [2, 4, 6, 8]
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Sum a list of numbers in Python
I have a list of numbers such as [1,2,3,4,5...] , and I want to calculate (1+2)/2 and for the second, (2+3)/2 and the third,
(3+4)/2 , and so on. How can I do that?
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What is Weak Head Normal Form?
...ains no un-evaluated thunks).
These expressions are all in normal form:
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(2, "hello")
\x -> (x + 1)
These expressions are not in normal form:
1 + 2 -- we could evaluate this to 3
(\x -> x + 1) 2 -- we could apply the function
"he" ++ "llo" -- we could apply...
how do I insert a column at a specific column index in pandas?
...e beginning
df.insert(loc, column, value)
df = pd.DataFrame({'B': [1, 2, 3], 'C': [4, 5, 6]})
df
Out:
B C
0 1 4
1 2 5
2 3 6
idx = 0
new_col = [7, 8, 9] # can be a list, a Series, an array or a scalar
df.insert(loc=idx, column='A', value=new_col)
df
Out:
A B C
0 7 1 4
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Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...当你把他的源码下下来编译后，你会发现解释器居然不到200k，这是多么地变态啊（/bin/sh都要1M，MacOS平台），而且能和C语言非常好的互动。我很好奇得浏览了一下Lua解释器的源码，这可能是我看过最干净的C的源码了。
我不想...
Regex to validate date format dd/mm/yyyy
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20 Answers
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How can I multiply and divide using only bit shifting and adding?
...fting you want to decompose one of the numbers by powers of two, like so:
21 * 5 = 10101_2 * 101_2 (Initial step)
= 10101_2 * (1 * 2^2 + 0 * 2^1 + 1 * 2^0)
= 10101_2 * 2^2 + 10101_2 * 2^0
= 10101_2 << 2 + 10101_2 << 0 (Decomposed)
= 10101_2 *...
Mean per group in a data.frame [duplicate]
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257
This type of operation is exactly what aggregate was designed for:
d <- read.table(text=
'...