#%% example -- can't change iterator during for loop, formatting display

for i in range(10):
    print(f'i is {i}, trying to change it to {3*i}')
    i = 3*i # don't do this (trying to change an iterator in a for loop)
    

#%% example -- find largest number divisible with 7 and smaller than 100    
i = 1
while i*7<100:
    i = i+1
print(7*i) # this will be larger than 100 -- so condition from while does not hold

#%% example -- vectorization

import numpy as np
test = np.array([3, 4, 8, 6, 5, 8, 3, 4, 7, 8, 8, 9, 4, 1, 3, 4, 6, 7, 9, 5, 3, 5, 7, 2, 5, 3])

## I want to count how many times does 8 appear in test

# One way of achieving this
count = 0
for t in test:
    if t==8:
        count += 1
        
# A better way of achieving this
count = (test==8).sum()


#%% I want to count how many times does each digit appear in test

# One way of achieving this
hist = np.zeros(10, dtype='int')
for i in range(len(hist)):
    hist[i] = (test==i).sum()

# Another way of achieving this
hist = np.zeros(10, dtype='int')
for t in test:
    hist[t] += hist[t]
    
 
#%% Avoid using break for better readability, if possible

# Without break: readable code, easly to see when while loop stops
i = 0
while i<101: 
    i = i+1
    print(i, end= ' ')
    
    
# With break: may be difficult to see when loop stops (especially in loops spanning many lines)
i = 0
while True:
    i = i+1
    print(i, end= ' ')
    if i>100:
        break