how to generate permutations of array in python?

python permutation
user257522 picture user257522 · Jan 23, 2010 · Viewed 33.4k times · Source

i have an array of 27 elements,and i don't want to generate all permutations of array (27!) i need 5000 randomly choosed permutations,any tip will be useful...

Answer

Mark Byers picture Mark Byers · Jan 23, 2010

To generate one permutation use random.shuffle and store a copy of the result. Repeat this operation in a loop and each time check for duplicates (there probably won't be any though). Once you have 5000 items in your result set, stop.

To address the point in the comment, Python's random module is based on the Mersenne Twister and has a period of 2**19937-1, which is considerably larger than 27! so it should be suitable for your use.

Related questions

How to generate all permutations of a list?

How do you generate all the permutations of a list in Python, independently of the type of elements in that list? For example: permutations([]) [] permutations([1]) [1] permutations([1, 2]) [1, 2] [2, 1] permutations([1, 2, 3]) [1, 2, 3] [1, 3, 2] [2, 1, 3] [2, 3, 1] [3, 1, 2] [3, 2, 1]

Read More
Shuffle DataFrame rows

I have the following DataFrame: Col1 Col2 Col3 Type 0 1 2 3 1 1 4 5 6 1 ... 20 7 8 9 2 21 10 11 12 2 ... 45 13 14 15 3 46 16 17 18 3 ... The DataFrame is read from a csv file. All rows which have Type 1 are on top, followed by the rows with Type 2, followed by the rows with Type 3, etc. I would …

Read More
Finding all possible permutations of a given string in python

I have a string. I want to generate all permutations from that string, by changing the order of characters in it. For example, say: x='stack' what I want is a list like this, l=['stack','satck','sackt'.......] Currently I …

Read More