Looping in Python 3.

looping.py

# Loop through list
for item in list:
  print(item)
  
# Loop through list with index
for index, item in enumerate(list):
  print(index, item)
  
# Loop through dictinary:
for key, value in dict.items():
  print(key, value)
  
# Loop through Numpy array:
for val in np.nditer(np_array):
  print(val)
  
# Loop through DataFrame: type(row): Series
for label, row in df.iterrows():
  print(label)
  print(row) 
  
# Loop and decrease without being below a specific value (e.g. 0)
value = 30
for i in range(10):
  value = max(0, value - 1)