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Zip lists in Python
...ch tuple contains, you could examine the length of the first element:
In [3]: result = zip(a, b, c)
In [4]: len(result[0])
Out[4]: 3
Of course, this won't work if the lists were empty to start with.
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How to drop columns by name in a data frame
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389
You should use either indexing or the subset function. For example :
R> df <- data.fram...
Append a NumPy array to a NumPy array
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234
In [1]: import numpy as np
In [2]: a = np.array([[1, 2, 3], [4, 5, 6]])
In [3]: b = np.array(...
Using numpy to build an array of all combinations of two arrays
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131
In newer version of numpy (>1.8.x), numpy.meshgrid() provides a much faster implementation:
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Pandas index column title or name
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394
You can just get/set the index via its name property
In [7]: df.index.name
Out[7]: 'Index Tit...
How to update gradle in android studio?
...Official links
Version Compatibility
Migrate to Android Plugin for Gradle 3.0.0
Find out the latest version of Gradle
Info about the Gradle Wrapper
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Apply a function to every row of a matrix or a data frame
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You simply use the apply() function:
R> M <- matrix(1:6, nrow=3, byrow=TRUE)
R> M
[,1] [,2]
[1,] 1 2
[2,] 3 4
[3,] 5 6
R> apply(M, 1, function(x) 2*x[1]+x[2])
[1] 4 10 16
R>
This takes a matrix and applies a (silly) function to each row. You pass extr...
finding and replacing elements in a list
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>>> a= [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1]
>>> for n, i in enumerate(a):
... if i == 1:
... a[n] = 10
...
>>> a
[10, 2, 3, 4, 5, 10, 2, 3, 4, 5, 10]
...
Sample random rows in dataframe
...rnorm(20), nrow=10))
> df
X1 X2
1 0.7091409 -1.4061361
2 -1.1334614 -0.1973846
3 2.3343391 -0.4385071
4 -0.9040278 -0.6593677
5 0.4180331 -1.2592415
6 0.7572246 -0.5463655
7 -0.8996483 0.4231117
8 -1.0356774 -0.1640883
9 -0.3983045 0.7157506
10 -0.9060305 2.3234...
how to change default python version?
I have installed python 3.2 in my mac. After I run /Applications/Python 3.2/Update Shell Profile.command , it's confusing that when I type python -V in Terminal it says that Python 2.6.1 , how can I change the default python version?
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