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Getting a list of 3 by 3 boxes in a Sudoku puzzle

Assuming the sudoku puzzle is a 9 by 9 and is filled with 0-9. I want is 9 lists, with each list containing a 3 by 3 Sudoku box.
This is what I have:
grid = [[5, 0, 0, 0, 0, 0, 0, 0, 1],
[0, 1, 0, 0, 8, 7, 0, 6, 0],
[0, 0, 0, 0, 0, 3, 0, 0, 0],
[0, 5, 0, 0, 6, 1, 0, 7, 0],
[0, 0, 2, 0, 0, 0, 9, 0, 0],
[0, 0, 0, 4, 0, 0, 0, 0, 0],
[0, 0, 0, 5, 0, 0, 0, 4, 0],
[9, 0, 0, 0, 4, 8, 7, 0, 0],
[0, 8, 0, 3, 0, 0, 0, 0, 0]]
list1 = []
for i in range(0,3):
for j in range(0,3):
list1.append(grid[i][j])
list2 = []
for i in range(0,3):
for j in range(4,7):
list2.append(grid[i][j])
and it goes on and on.......
How do I simplify this for loop for getting a list of 3 by 3 boxes in Sudoku puzzle?

You need to add a step parameter to your range()s so that you start reading in each box at the appropriate row / column index:
from itertools import product
boxes = []
for row_start, col_start in product(range(0, 9, 3), repeat=2):
boxes.append([
[grid[row][col] for col in range(col_start, col_start + 3)]
for row in range(row_start, row_start + 3)
])
print(boxes)
This outputs:
[
[[5, 0, 0], [0, 1, 0], [0, 0, 0]],
[[0, 0, 0], [0, 8, 7], [0, 0, 3]],
[[0, 0, 1], [0, 6, 0], [0, 0, 0]],
[[0, 5, 0], [0, 0, 2], [0, 0, 0]],
[[0, 6, 1], [0, 0, 0], [4, 0, 0]],
[[0, 7, 0], [9, 0, 0], [0, 0, 0]],
[[0, 0, 0], [9, 0, 0], [0, 8, 0]],
[[5, 0, 0], [0, 4, 8], [3, 0, 0]],
[[0, 4, 0], [7, 0, 0], [0, 0, 0]]
]

from pprint import pprint as pp
SIZE = 3
sudoku = [[[0] * SIZE for _ in range(SIZE)] for _ in range(SIZE * SIZE)]
# example of populating it
for i in range(SIZE):
for j in range(SIZE):
counter = i * SIZE + j
sudoku[counter][i][j] = counter + 1
pp(sudoku)
output
[[[1, 0, 0], [0, 0, 0], [0, 0, 0]],
[[0, 2, 0], [0, 0, 0], [0, 0, 0]],
[[0, 0, 3], [0, 0, 0], [0, 0, 0]],
[[0, 0, 0], [4, 0, 0], [0, 0, 0]],
[[0, 0, 0], [0, 5, 0], [0, 0, 0]],
[[0, 0, 0], [0, 0, 6], [0, 0, 0]],
[[0, 0, 0], [0, 0, 0], [7, 0, 0]],
[[0, 0, 0], [0, 0, 0], [0, 8, 0]],
[[0, 0, 0], [0, 0, 0], [0, 0, 9]]]

Change zeroes in 2D array one by one, and put the resulting arrays into another array in Python [duplicate]

This question already has answers here:
How do I compute all possibilities for an array of numbers/bits (in python, or any language for that matter)
(5 answers)
Closed 2 years ago.
I am trying to achieve the following. I have a 2D array, which is of a 4x4 dimension. I want to get all possibilities, where I can insert a single 1 instead of a zero, and return an array, which contains all of these possibilities
So if we take:
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
would result in:
[[1, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 1, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 1], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
...
There would be a total of 14 entries in the resulting array, since there were 14 zeroes in the input array.
The problem is, that the code I have currently should work, as far as I understand, but I can't seem to get where it goes wrong.
def getPossibilities(arr):
p = []
for i in range(4):
for j in range(4):
if arr[i][j] == 0:
p.append(arr)
p[-1][i][j]=1
return p
for i in getPossibilities([[0,1,0,0],[0,0,1,0],[0,0,0,0],[0,0,0,0]]):
print(i)
This results in 14 arrays of solid ones.
I included the way I check the results, in case there is an error there. I also tried with first copying the arr array into a temporary one, then make the changes, but to no avail.
What goes wrong here? I cannot seem to find an answer. Also, is there a more elegant and faster way of doing this? It would be really beneficial for my usecase.
Thank you very much in advance!

This is somewhat tricky but since you have a list of lists, the copy won't work and you will be changing the array every time, what you need is deepcopy:
import copy
def getPossibilities(arr):
p = []
for i in range(4):
for j in range(4):
if arr[i][j] == 0:
tmp = copy.deepcopy(arr)
tmp[i][j]=1
p.append(tmp)
return p
for i in getPossibilities([[0,1,0,0],[0,0,1,0],[0,0,0,0],[0,0,0,0]]):
print(i)
[[1, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 1, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 1], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [1, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 1, 1, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 1], [0, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [1, 0, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 1, 0], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1], [0, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [1, 0, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 1, 0, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 1, 0]]
[[0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 0], [0, 0, 0, 1]]

fill numpy array with sequence of numbers

I have a numpy array with the shape (6, 3, 4) that I'd like to fill with an ascending sequence of numbers so that the resulting array is this:
array([[[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]],
[[1, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]],
[[2, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]],
[[3, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]],
[[4, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]],
[[5, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0]]], dtype=uint8)
I do not want to use a loop, if possible.
I've tried the following with no luck:
import numpy as np
new_row = np.zeros([6, 3, 4], dtype=np.uint8)
new_row[:,0:1,0:1] = range(6)
which results in ValueError: could not broadcast input array from shape (6) into shape (6,1,1)
Any help appreciated

Initialize an empty multidimensional list

I would like to initialize a multidimensional list capable of storing an object for every minute since year 1950-2050.
Something like:
minute = [None]*61
hour = [minute]*25
day = [hour]
month = [day]
data = [month]*100
So you can do:
data[89][1][29][23][55] = 'It was a good minute the one from January 29th in 1989 when it was 23:55'
How would be such a multidimensional list be initialized in Python? Would it be an actual different object than the one created with the above code?
Initially the multidimensional list would contain objects None.
Python 2.7
Following answer I tried:
# Data structure
minute = 60
hour = 24
day = 31
month = 12
year = 100
test = [[[[[None for _minute in range(minute)] for _hour in range(hour)] for _day in range(day)] for _month in range(month)] for _year in range(year)]
But it seems too much for multidimensional lists, as I get "Killed" when trying to execute this.

I also don't recommend this, but you could use a numpy.chararray for this:
import numpy as np
arr = np.chararray((100, 12, 31, 24, 60, 60), itemsize=100)
arr[52, 7, 12, 12, 44, 54] = 'year 1950+52, 7th month, 12th day, 12th hour, 44th minute, 54th second'
I'm not exactly sure what your desired structure is, but the string I inserted into the array should explain the structure I proposed, and you can change it however you need. Note that itemsize limits how many characters you can put in at any index.
Again, with a caveat that this is not necessarily the most efficient thing in the world to do, but if you wish to store lists of ints and/or floats in that array (as per your comment), one way to do it would be to convert that list to strings, and then when retrieving it, re-transform back to a list:
data_to_insert = [1,2,3,4.5]
# store as string
arr[52, 7, 12, 12, 44, 54] = ','.join(map(str, data_to_insert))
# retrieve
arr[52, 7, 12, 12, 44, 54].decode('utf-8').split(',')
This should be pretty fast

Though i won't recommend it,
A multi dimentional empty list can be created by using list comprehension:
> >>> a = 4 #Width of elements
> >>> b = 6 #Width of main list container
>>>>> c = 4
>>>>> d = 3
> >>> l = [[[[0 for k in range(d) ] for z in range(c)] for x in range(a)] for y in range(b)]
> >>> [[[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]], [[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]], [[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]], [[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]], [[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]], [[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]], [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]]]
Keep replacing 0 with list comprehensions to add more dimentions.

Python List Assignment Issues

#DeckOfCards
deck = []
filler= [0, 0, 0, 0]
def deck_generator():
counter = 0
for i in range (52):
counter += 1
deck.append(filler)
return deck
def deck_values(i):
k = 4
temp = (i + 1) % k
return temp
deck = deck_generator()
for i in range(52):
deck[i][0] = deck_values(i)
The goal with this code is to assign the values 0-3 inclusive to the first index of the inner list to all values in the outer list.
[[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0], [0, 0, 0, 0]] and so on. For some reason the assignment just does not work. Thanks in advance.

Append a copy of the list instead of the list itself.
deck.append(filler[:])

Try this
deck = []
for i in range(52):
deck.append([i % 4, 0, 0, 0])
print (deck)
Running this code prints (edited for ease of viewing):
[[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],
[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0]]

are you sure you want to get [[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0], [0, 0, 0, 0]] ?
first of all, you should use the copy of filter and then you can get a list like:
[[1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0], [0, 0, 0, 0],...]
but if you want to get the result [[0, 0, 0, 0], [1, 0, 0, 0], [2, 0, 0, 0], [3, 0, 0, 0],...]
your codes should be like this:
deck = []
filler= [0, 0, 0, 0]
def deck_generator():
counter = 0
for i in range (52):
counter += 1
deck.append(filler[:])
return deck
def deck_values(i):
k = 4
temp = i % k #not temp = (i+1) % k
return temp
deck = deck_generator()
for i in range(52):
deck[i][0] = deck_values(i)
print(deck)

I think the issue with it is temp=(i+1)%k as we do not need to add 1 to 1. It should start from 0. In addition to this, you need to append properly so it works. The code would look like this:
#DeckOfCards
deck = []
filler= [0, 0, 0, 0]
def deck_generator():
counter = 0
for i in range (52):
counter += 1
deck.append(filler[:])
return deck
def deck_values(i):
k = 4
temp = (i) % k
return temp
deck = deck_generator()
for i in range(52):
deck[i][0] = deck_values(i)