'''
Python 3.6.9 (default, Nov  7 2019, 10:44:02) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.

In Ubuntu 18.04.3
'''

## Demonstration of result depending on how matrix A is constructed
###################################################################

### creating text with 25 characters (25 = 5 x 5)
tekst = 'All hands on deck.*******'

# j is sqrt(25)
j=5
    
#Creating a 5 x 5 square natrix A

### First trial
## A is defined in a straight manner, filling it with numbers as B
## in the second trial
A=[[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4]]

# initial state of experiment
print(A)
print(j)
print(tekst)


#Now the experiment itself, with defined A:
for r in range(j):
    for k in range(j):
        A[r][k] = tekst[j*r+k]

print(A)
### Success!
print("This result is great!")
print()


## Second trial goes wrong:
# B is created by creating a row first, and then filling B with the rows
# B is filled with numbers too, not the same numbers just like A but 
# that shouldn't matter

# creating a row with numbers first
row=[]
for k in range(j):
    row.append(k)
#next creating the matrix B
B=[]
for r in range(j):
    B.append(row)

# Initial state experiment    
print(B)
print(j)
print(tekst)   

# Experiment itself
for r in range(j):
    for k in range(j):
        B[r][k] = tekst[j*r+k]

print(B)
### Disaster!
print("Disastrous result: all rows are equal to the last one")
print()


### THIRD experiment
### Check whether A and B are the same or equal immediately after their
### definition/constructions

A=[[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4],[0,1,2,3,4]]

# construction of B
row=[]
for k in range(j):
    row.append(k)
#next creating the matrix B
B=[]
for r in range(j):
    B.append(row)
    
print()
print("A and B immediately after creation:")
print()    

print("A is ", A)
print()
print("B is ", B)
print()
print("A is B : ", A is B)
print("A == B : ", A == B)
print()
 



'''
##### RESULTS
###
jaap@bromo:~/Bureaublad$ python3 codevierkant_experiment.py 
[[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15], [16, 17, 18, 19, 20], [21, 22, 23, 24, 25]]
5
All hands on deck.*******
[['A', 'l', 'l', ' ', 'h'], ['a', 'n', 'd', 's', ' '], ['o', 'n', ' ', 'd', 'e'], ['c', 'k', '.', '*', '*'], ['*', '*', '*', '*', '*']]
This result is great!

[[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4]]
5
All hands on deck.*******
[['*', '*', '*', '*', '*'], ['*', '*', '*', '*', '*'], ['*', '*', '*', '*', '*'], ['*', '*', '*', '*', '*'], ['*', '*', '*', '*', '*']]
Disastrous result: all rows are equal to the last one


THIRD experiment:

A and B immediately after their creation:

[[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4]]
[[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4]]
False
True    <=========

This means that the matrix B is equal to the matrix A, immediately after their construction!
But their behaviour is different!

jaap@bromo:~/Bureaublad$ 

'''