Python while loop - differences in similar codes

The first while has an additional "square=squares[i]". If you change it like this, you will get the same results:

# code1
squares = ['orange', 'orange', 'red']
new_squares = []

i=0
square=squares[0]

while(square=='orange'):
    square=squares[i]
    new_squares.append(square)
    i = i + 1
print(new_squares)


# code2
squares = ['orange', 'orange', 'red']
new_squares = []

i = 0
while(squares[i] == 'orange'):
    new_squares.append(squares[i])
    i = i + 1
print (new_squares)

SEE COMMENTS TO UNDERSTAND HOW IT WORKS FOR ALL PASSES:

    # code1
squares = ['orange', 'orange', 'red']     #ist pass                2nd pass                    3rd pass                   4th pass 
new_squares = []

i=0                                       # i=0
square=squares[0]                       # square='orange'

while(square=='orange'):                # true                      true                        true                    false
    new_squares.append(square)          # orange0 appended          orange0 appended again      orange1 appended
    square=squares[i]                   # as i=0, square='orange'   i=1,square='orange1'      i=2, so square='red'
    i = i + 1                           # now i=1                    i=2                       i=3
print(new_squares)                         


# code2
squares = ['orange', 'orange', 'red']    
new_squares = []

i = 0                                   #i=0                           
while(squares[i] == 'orange'):          # true                        true                       false
    new_squares.append(squares[i])      # orange0 appended          orange1 appended as i=1
    i = i + 1                           # i=1                       i=2
print (new_squares)

Think about how the code runs:

squares = ['orange', 'orange', 'red']
new_squares = []

i=0
square=squares[0]


while(square=='orange'):
    new_squares.append(square)
    square=squares[i]
    i = i + 1
print(new_squares)

On iteration one:

squares = ['orange', 'orange', 'red']
new_squares = []

i=0
square=squares[0] #square = 'orange'


while(square=='orange'):
    new_squares.append(square) # new_squares = ['orange']
    square=squares[i] # i = 0; squares[0] = 'orange'
    i = i + 1 # i = 1
print(new_squares)

Second iteration:

squares = ['orange', 'orange', 'red']
new_squares = []

i=0



while(square=='orange'):
    # square = 'orange' from previous 
    new_squares.append(square) # new_squares = ['orange', 'orange']
    square=squares[i] # i = 1 from previous; squares[1] = 'orange'
    i = i + 1 # i = 2
print(new_squares)

Final iteration:

squares = ['orange', 'orange', 'red']
new_squares = []

i=0



while(square=='orange'):
    # square = 'orange' from previous 
    new_squares.append(square) # new_squares = ['orange', 'orange', 'orange']
    square=squares[i] # i = 2 from previous; squares[2] = 'red'
    i = i + 1 # i = 3
print(new_squares)

Take look on first code. And exactly let's pay attention on the first iteration in loop.

# First of all, you set `square` to zero element in array.

i=0
square=squares[0]   # <---- here it is. 

while(square=='orange'):   # <--- then you check is zero element still "orange", and it is
    new_squares.append(square)
    square=squares[i]      # i still equal to 0. here you again set `square` to zero element in array. I believe you want to set it on next element. But your i still = 0.
    i = i + 1              # and only here i set to 1, so you should cnange the order of this command
print(new_squares)

Here is the fixed version:

i=0
square=squares[0]

while(square=='orange'):
    new_squares.append(square)
    i = i + 1     # here firstly you increase i, and now it 1
    square=squares[i]  # here you get the next element

print(new_squares)