大约有 49,000 项符合查询结果（耗时：0.0447秒） [XML]
How can I get nth element from a list?
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156
Look here, the operator used is !!.
I.e. [1,2,3]!!1 gives you 2, since lists are 0-indexed.
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Looping over a list in Python
...n mylist[:] and your len(x) should be equal to 3.
>>> mylist = [[1,2,3],[4,5,6,7],[8,9,10]]
>>> for x in mylist:
... if len(x)==3:
... print x
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[1, 2, 3]
[8, 9, 10]
or if you need more pythonic use list-comprehensions
>>> [x for x in mylist if len(x)==3...
How to insert element into arrays at specific position?
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214
array_slice() can be used to extract parts of the array, and the union array operator (+) can r...
Slicing of a NumPy 2d array, or how do I extract an mxm submatrix from an nxn array (n>m)?
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As Sven mentioned, x[[[0],[2]],[1,3]] will give back the 0 and 2 rows that match with the 1 and 3 columns while x[[0,2],[1,3]] will return the values x[0,1] and x[2,3] in an array.
There is a helpful function for doing the first example I gave, numpy.ix_....
Most efficient way of making an if-elif-elif-else statement when the else is done the most?
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100
The code...
options.get(something, doThisMostOfTheTime)()
...looks like it ought to be fast...
Multiple linear regression in Python
... regress my dependent variable (y) against several independent variables (x1, x2, x3, etc.).
13 Answers
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Getting list of lists into pandas DataFrame
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271
Call the pd.DataFrame constructor directly:
df = pd.DataFrame(table, columns=headers)
df
He...
python pandas: apply a function with arguments to a series
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170
Newer versions of pandas do allow you to pass extra arguments (see the new documentation). So ...
Dynamically select data frame columns using $ and a character value
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185
You can't do that kind of subsetting with $. In the source code (R/src/main/subset.c) it state...
Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
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119
I'd just use zip:
In [1]: from pandas import *
In [2]: def calculate(x):
...: return ...