I would suggest %matplotlib notebook It will still have to a nice png, but you get an interactive figure when it is live. I agree that making the example code Python3 is critical. Tom On Thu, Oct 1, 2015 at 8:05 PM Jaime Fernández del Río <jaime.frio@gmail.com> wrote:

On Thu, Oct 1, 2015 at 11:46 AM, Alex Rogozhnikov < alex.rogozhnikov@yandex.ru> wrote:

...

Hi, I have written some numpy tips and tricks I am using, which may be interesting to you. This is quite long reading, so I've splitted it into two parts:

http://arogozhnikov.github.io/2015/09/29/NumpyTipsAndTricks1.html

The recommendation of inverting a permutation by argsort'ing it, while it works, is suboptimal, as it takes O(n log(n)) time, and you can do it in linear time:

In [14]: import numpy as np

In [15]: arr = np.random.rand(10)

In [16]: perm = arr.argsort()

In [17]: perm Out[17]: array([5, 0, 9, 4, 2, 8, 6, 7, 1, 3])

In [18]: inv_perm = np.empty_like(perm)

In [19]: inv_perm[perm] = np.arange(len(perm))

In [20]: np.all(inv_perm == perm.argsort()) Out[20]: True

It does require two lines of code, so for small stuff it is probably good enough to argsort, but it gave e.g. np.unique a nice boost on larger arrays when we applied it there.

Jaime

...

http://arogozhnikov.github.io/2015/09/30/NumpyTipsAndTricks2.html

Comments are welcome, specially if you know any other ways to make this code faster (or better).

Regards, Alex.

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I would suggest

%matplotlib notebook

It will still have to a nice png, but you get an interactive figure when it is live.

Amazing, thanks. I was using mpld3 for this. (for some strange reason I need to put %matplotlib notebook before each plot)

The recommendation of inverting a permutation by argsort'ing it, while it works, is suboptimal, as it takes O(n log(n)) time, and you can do it in linear time: Actually, there is (later in post) a linear solution using bincount, but your code is definitely better. Thanks!

2015-10-02 9:48 GMT+02:00 Kiko <kikocorreoso@gmail.com>:

2015-10-02 9:38 GMT+02:00 Alex Rogozhnikov <alex.rogozhnikov@yandex.ru>:

...

I would suggest

...

%matplotlib notebook

It will still have to a nice png, but you get an interactive figure when it is live.

Amazing, thanks. I was using mpld3 for this. (for some strange reason I need to put %matplotlib notebook before each plot)

You should create a figure before each plot instead of putthon %matplotlib notebook plt.figure() ....

putthon == putting

...

The recommendation of inverting a permutation by argsort'ing it, while it

...

works, is suboptimal, as it takes O(n log(n)) time, and you can do it in linear time:

Actually, there is (later in post) a linear solution using bincount, but your code is definitely better. Thanks!

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