Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>sorry the only way to make it faster is by using numpy :/. No matter what you do it has to somehow scramble all the indices which takes time - so doing it in C will help slightly. Also the difference between sheer random and this random is that you can't have repeated indices.</p> <p>sorry it's sort of long now - so you'll have to do some scrolling</p> <pre><code>E.g. # made for python 2.7 but should be able to work in python 3 import random import numpy as np from time import time def given_seq(): #general example start = time() a = {"one":1,"two":2,"three":3} keys = a.keys() random.shuffle(keys) a = dict(zip(keys, a.values())) #Large example a = dict(zip(range(0,100000), range(1,100001))) def random_shuffle(): keys = a.keys() random.shuffle(keys) b = dict(zip(keys, a.values())) def np_random_shuffle(): keys = a.keys() np.random.shuffle(keys) b = dict(zip(keys, a.values())) def np_random_permutation(): #more concise and using numpy's permutation option b = dict(zip(np.random.permutation(a.keys()), a.values())) #if you precompute the array key as a numpy array def np_random_keys_choice(): akeys = np.array(a.keys()) return dict(zip(akeys[np.random.permutation(len(akeys))],a.values())) def np_random_keys_shuffle(): key_indexes = np.arange(len(a.keys())) np.random.shuffle(key_indexes) return dict(zip(np.array(a.keys())[key_indexes],a.values())) #fixed dictionary size key_indexes = np.arange(len(a.keys())) def np_random_fixed_keys_shuffle(): np.random.shuffle(key_indexes) return dict(zip(np.array(a.keys())[key_indexes],a.values())) #so dstack actually slows things down def np_random_shuffle_dstack(): keys = a.keys() np.random.shuffle(keys) return dict(np.dstack((keys, a.values()))[0]) if __name__=='__main__': import timeit # i can use global namespace level introspection to automate the below line but it's not needed yet for func in ['given_seq', 'random_shuffle', 'np_random_shuffle', 'np_random_permutation', 'np_random_keys_choice', 'np_random_keys_shuffle', 'np_random_fixed_keys_shuffle']: print func, timeit.timeit("{}()".format(func), setup = "from __main__ import {}".format(''.join(func)), number = 200) </code></pre> <blockquote> <pre><code>given_seq 0.00103783607483 random_shuffle 23.869166851 np_random_shuffle 16.3060112 np_random_permutation 21.9921720028 np_random_keys_choice 21.8105020523 np_random_keys_shuffle 22.4905178547 np_random_fixed_keys_shuffle 21.8256559372 </code></pre> </blockquote> <p>Using Choice/Permutation may look nicer - but it's not faster by any means. Unfortunately copying is usually slow unless it's a small size - and there's no way to pass pointers/references without it having to take up an extra line - though I debate if this makes it 'non-pythonic'</p> <p>namely if you look at the <a href="http://www.python.org/dev/peps/pep-0020/" rel="nofollow">Zen of Python</a> or just do <code>import this</code> in a python session one of the lines is:</p> <blockquote> <p>Although practicality beats purity.</p> </blockquote> <p>so it's open to interpretation of course :)</p>
    singulars
    1. This table or related slice is empty.
    1. PORandomly Shuffle Keys and Values in Python DIctionary
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USEiyrioü von Kauyf
    1. USEiyrioü von Kauyf
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PORandomly Shuffle Keys and Values in Python DIctionary
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COFor some reason when I use np.random.shuffle on a list such as a.keys() it returns an object of type 'NoneType'. This obviously then fails when I zip. Same happens when I use random.shuffle. Ideas?
      singulars
      1. PO
      1. USbrebs
    2. CO``np.random.shuffle`` shuffles an object in place. In my mind it's scrambling the pointers behind the scenes, so it can't give you back an object because it never copies it :) - it's faster to just play with pointers as a giant array can have a few million ints, whereas a pointer and a length / end pointer are magnitudes of size less
      singulars
      1. PO
      1. USEiyrioü von Kauyf
    3. COThank you! I was trying to save it as a new variable. I didn't realize it simply shuffled the original. It works now.
      singulars
      1. PO
      1. USbrebs
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload