How I can find a number of all connecting cells which filled with 1 in matrix NxN? (Python).

Question

Problem connecting cells. For example matrix 4x4
a = [[1,0,0,1]
[0,0,1,1]
[0,0,0,0]
[1,1,0,0]]
In this matrix a number of connecting cells equal 3.
1st: a[0][0]

2nd:a[0][3], a[1][2], a[1][3]

3rd: a[2][0], a[2][1]

Answer 1

Rustam, the first part adds extra row of 0s and flattens the matrix to one list. the second part searches for all spaces around each node except the space directly above and on the top left. but, why that works i honestly dont know! im sorry! i just kept messing with it until it worked 🤔

Answer 2

Rustam, no need for sorry it's ok 👌

Can you perhaps show another example, maybe a 3x3 matrix or something. I ask because I'm still unsure what output is expected and how to format the output.

Actually, I still don't quite understand the term "connecting cells" : )

Answer 3

Madeline . Yes

Answer 4

Oh okay 👌
Looks pretty tough Rustam, maybe I'll get back if I come up with something. Right now, no idea ...

Answer 5

Thanks

Answer 6

there is quite a bit of theory on this problem. it is called “find thd number of islands” problem and there are ideas about depth first search and breadth first search. just fyi! thanks!!!

Answer 7

What you mean connecting cells?!

Answer 8

Rustam find in inet percolation algorithm.

Answer 9

did you want all connecting 1s or only the longest group of them?

Answer 10

i guess i need a clearer question lol

Answer 11

How I can find a number of all connecting cells which filled with 1 in matrix NxN? (Python).
I mean ,

Problem connecting cells. For example matrix 4x4
a = [[1,0,0,1]
[0,0,1,1]
[0,0,0,0]
[1,1,0,0]]
In this matrix a number of connecting cells equal 3.
1st: a[0][0]

2nd:a[0][3], a[1][2], a[1][3]

3rd: a[2][0], a[2][1]

Answer 12

oh i gotcha! you want the number of groups of 1s. i’ll work on that. thank you for the challenge. but... i can already see where it will be tough!!!

Answer 13

Rustam,
Are you sure about the 3rd a[2][0], a[2][1]

a[2] contains zero only ...

I think maybe you mean a[3][0], a[3][1] because there are two values of 1 there.

Answer 14

Ipang ok. This is 3x3 matrix
[0][1][0]
[0][0][1]
[1][1][0]
In this matrix a number of connected cells are
1. Because all cells which filled with 1 are neighbors each other.

Answer 15

George thank you

Answer 16

Rustam
Correct me if I'm wrong understanding ...

In 3x3 matrix above, the 3rd row [1, 1, 0] is the only one connected cell because it contains two adjacent value of 1. Did I get it right this time?

Answer 17

Ipang. No you're wrong. Because [2][1] cell is neighbour with [1][2] and [1][2] cell is neighbour with [0][1] cell. All of them filled with 1 and neighbors each other. All of them connected with each other.

Answer 18

he is also counting diagonals it looks like

Answer 19

i am working on it now haha and its rly hard to say the least...

Answer 20

Madeline thank you. It's working. Can you explain me this code?