Method Name:
perm()
Method Signature:
perm(n, k=None)
Parameters:
n – Number of items
k – Number of items to be chosen.
Return value:
Returns the number of ways to select ‘k’ items from number of items ‘n’, with order and without repetition.
Overview:
- Like the comb() function perm() is a combinatoric function.
- The perm() function of Python math module returns the number of ways to select ‘k’ items from number of items ‘n’, with order and without repetition.
- The computation is given by: n! / (n - k)!, where k <= n; returns zero when 'k' is greater than 'n'.
- When ‘k’ is None or when ‘k’ is equal to ‘n’, the function returns n! .
Example:
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# Example python program to compute permutations - Number of ways to choose k items from n # items import math
totalItems = 52; # n itemsToChoose = 5; # k
# Number of ways to choose k items from n items (without repetition and with order) permutations = math.perm(totalItems, itemsToChoose);
print("Number of ways to choose %d items(k) from %d items(n)(without repetition & with order):"%(totalItems, itemsToChoose)); print(permutations); |
Output:
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Number of ways to choose 52 items(k) from 5 items(n)(without repetition & with order): 311875200 |