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How do you extract a column from a multi-dimensional array?
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234
>>> import numpy as np
>>> A = np.array([[1,2,3,4],[5,6,7,8]])
>>> ...
Fast check for NaN in NumPy
...hine it is about 2.5x faster to use numpy.sum in place of numpy.min:
In [13]: %timeit np.isnan(np.min(x))
1000 loops, best of 3: 244 us per loop
In [14]: %timeit np.isnan(np.sum(x))
10000 loops, best of 3: 97.3 us per loop
Unlike min, sum doesn't require branching, which on modern hardware tends...
How to “properly” print a list?
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In Python 2:
mylist = ['x', 3, 'b']
print '[%s]' % ', '.join(map(str, mylist))
In Python 3 (where print is a builtin function and not a syntax feature anymore):
mylist = ['x', 3, 'b']
print('[%s]' % ', '.join(map(str, mylist)))
Both return:
[x, 3,...
Is there a foreach in MATLAB? If so, how does it behave if the underlying data changes?
...in other languages. This means that the following code always prints 1, 2, 3, 4, 5 regardless of the value of B.
A = 1:5;
for i = A
A = B;
disp(i);
end
If you want to be able to respond to changes in the data structure during iterations, a WHILE loop may be more appropriate --- you'll be...
Select multiple columns in data.table by their numeric indices
... all just work:
library(data.table)
dt <- data.table(a = 1, b = 2, c = 3)
# select single column by index
dt[, 2]
# b
# 1: 2
# select multiple columns by index
dt[, 2:3]
# b c
# 1: 2 3
# select single column by name
dt[, "a"]
# a
# 1: 1
# select multiple columns by name
dt[, c("a", ...
Get integer value from string in swift
...ft 2.0 you can initialize Integer using constructor
var stringNumber = "1234"
var numberFromString = Int(stringNumber)
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std::next_permutation Implementation Explanation
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Let's look at some permutations:
1 2 3 4
1 2 4 3
1 3 2 4
1 3 4 2
1 4 2 3
1 4 3 2
2 1 3 4
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How do we go from one permutation to the next? Firstly, let's look at things a little differently. We can view the elements as digits and the permutations as numbers. ...
Easiest way to upgrade eclipse 3.7 to 4.2 (Juno)
So since Eclipse juno is based on 4.2 instead of 3.7, what is the easiest way to upgrade to it, short of installing a separate copy of juno and re-installing all my existing plugins from 3.7 into it?
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How to run multiple Python versions on Windows
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136
Running a different copy of Python is as easy as starting the correct executable. You mention t...