Generate lists with elements less or equal to the given list

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What is the most pythonic way to solve the following problem?

Given a list A, find all lists B, such that for i in range(len(A)): B[i] <= A[i]. Example of what I expect:

A = [1,2,0]
B = [[0,0,0],

Thanks in advance!

You can use itertools.product to do this easily

>>> from itertools import product
>>> A
[1, 2, 0]
>>> B = list(product(*[list(range(e+1)) for e in A]))
>>> B
[(0, 0, 0), (0, 1, 0), (0, 2, 0), (1, 0, 0), (1, 1, 0), (1, 2, 0)]

If you want the o/p as list of list, convert the tuples to list

>>> B = [list(e) for e in B]
>>> B
[[0, 0, 0], [0, 1, 0], [0, 2, 0], [1, 0, 0], [1, 1, 0], [1, 2, 0]]

If you dont wan't to use itertools.product, you can have your custom implementation of product

>>> B = [[]]; 
>>> for t in [range(e+1) for e in A]:
...     B = [x+[y] for x in B for y in t]
>>> B
[[0, 0, 0], [0, 1, 0], [0, 2, 0], [1, 0, 0], [1, 1, 0], [1, 2, 0]]

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Here is a quite smart solution without using itertools but using recursive function call. It works whatever the size of the input list:

A = [1,2,0]

def compute(A, B=[], n=0):
    for i in range(A[n]+1):
        A[n] = i
        if A not in B: B.append(A[:])
        if n+1 < len(A): compute(A, B, n+1)  # recursive call here
    return sorted(B)

B = compute(A)

# [[0, 0, 0], [0, 1, 0], [0, 2, 0], [1, 0, 0], [1, 1, 0], [1, 2, 0]]

Python, By traversing in the list, we can compare every element and check if all the elements in the given list are greater than the given value or not. filter_none. edit close. Given a list, write a Python program to check if all the values in a list are less than the given value. Examples: Input : list = [11, 22, 33, 44, 55] value = 22 Output : No Input : list = [11, 22, 33, 44, 55] value = 65 Output : Yes

I guess you could first generate all unique combinations of these numbers:

>>> import itertools
>>> A = [1,2,0]
>>> combs = set(itertools.combinations(itertools.chain(*(range(col+1) for col in A)), len(A)))
>>> combs
{(0, 1, 1), (0, 2, 0), (1, 1, 0), (1, 2, 0), (0, 0, 2), (0, 1, 2), (1, 0, 0), (0, 0, 1), (1, 0, 1), (1, 1, 2), (0, 0, 0), (0, 1, 0), (1, 0, 2)}

Then pick the ones that follow your condition:

>>> sorted(comb for comb in combs if all(comb[i] <= x for i, x in enumerate(A)))
[(0, 0, 0), (0, 1, 0), (0, 2, 0), (1, 0, 0), (1, 1, 0), (1, 2, 0)]

But this is alot more inefficient than using itertools.product, since it has to generate all the combinations beforehand, and sort at the end to retain order.

11. Lists, The values that make up a list are called its elements, or its items. We will ways to create a new list; the simplest is to enclose the elements in square brackets ([ and ]): The function len returns the length of a list, which is equal to the number of its elements. Write a function to return a list of all prime numbers less than n:​  For each element in 1st array count elements less than or equal to it in 2nd array | Set 2 Count equal element pairs in the given array Check if the array has an element which is equal to XOR of remaining elements

This also works:

A = [1,2,0]

answers = [[] for element in A]
answers[0] = [[number,] for number in range(A[0]+1)]

for i in range(len(A)-1):
    for possibility in answers[i]:
        for valid_number in range(A[i+1]+1):
            answers[i+1].append(possibility + [valid_number, ])

your_answer = answers[-1]

It could probably be written in a more compact way.

9. Lists, The syntax for accessing the elements of a list is the same as the syntax for Lists that contain consecutive integers are common, so Python provides a simple way to create If the step size is negative, then start must be greater than stop. Lists in LISP. Although cons cells can be used to create lists, however, constructing a list out of nested cons function calls can't be the best solution. The list function is rather used for creating lists in LISP. The list function can take any number of arguments and as it is a function, it evaluates its arguments.

Python: Find all the values in a list are greater than a specified , Previous: Write a Python program to find the list in a list of lists whose sum of elements is the highest. Next: Write a Python program to extend a list  Given the positive integers m and n (with m < n) create a list consisting of the portion of the Fibonacci sequence greater than or equal to m and less than or equal to n. For example, if m is 3 and n is 6, then the list would be [3, 5] and if m is 2 and n is 20, then the list would be [2, 3, 5, 8, 13].

18 Most Common Python List Questions, Discover how to create a list in Python, select list elements, the difference How To Create Empty NumPy Arrays; How To Do Math With Lists pass an integer value to the index operator that is bigger or way smaller than your list! The step value is set equal to the chunkSize value you pass to chunks() . Python lists chapter of the Python tutorial covers Python lists. Python list is an ordered collection of elements.

Lists - Learn Python 3, Lists · Even indices · Even elements · Greater than previous · Neighbors of the same sign A list is a sequence of elements numbered from 0, just as characters in the string. Consider several ways of creating and reading lists. The resulting list c will be equal to [1, 2, 3, 4, 5] , and a list of d will be equal to [4, 5, 4, 5, 4, 5] . In F#, a list is an ordered, immutable series of elements of the same type. It is to some extent equivalent to a linked list data structure. The F# module, Microsoft.FSharp.Collections.List, has the common operations on lists. However F# imports this module automatically and makes it accessible to every F# application. Using list literals.

  • Sounds like homework.
  • Great! The itertools was in my list. Unfortunatelly, I'm not allowed to use any side libraries. Maybe there are straightforward solutions without it? Thanks!
  • I can't see it working for an arbitrary len(A). Am I missing something? Is is possible to extend your second solution to any len(A)?
  • Updated the answer
  • @Sanitha, looks awesome! Maybe you know, why does the itertools implementation work much faster than the custom implementation? Thanks!