Question

write a Python3 code that finds the mode of any numerical list, without using:
statistics.mode()
max()
.sort
.count
squiggly brackets (like {})
Please also make it so that the code is able to return the number of times it loops.

Answer 1

I have implemented the program as required.Please find the code and the screenshots below.

Code:

def find_mode(lst):
nums = [] # list to store the numbers without repetitions
mx = -1 # variable to store max value
mx2 = -1 # variable to store 2nd max value
temp1 = [] # list to store occurences for each variable
temp = lst.copy() # copy lst in temp
# temp will be used in this way: if lst = [2, 5, 3, 2, 5, 5, 2] then temp = [1, 1, 1, 2, 2, 3, 2]
multimode = False # assume there is only one mode
count = 0 # variable to store number of times it loops
for i in range(len(lst)):
count += 1
if lst[i] not in nums:
nums.append(lst[i])   
temp1.append(1)   
temp[i] = 1   
else:
ind = nums.index(lst[i])
temp1[ind] += 1
temp[i] = temp1[ind]
if temp[i]>=mx:
mx2 = mx
mx = temp[i]
mxind = i
if mx2 == mx:
multimode = True
if mx == 1:
print('No Mode Found')
print('The program looped {} times'.format(count))
else:
if multimode:
print('The modes are:',end = ' ')
for j in range(len(temp)):
count += 1
if temp[j] == mx:
print(lst[j],end = ', ')
print('\nThe program looped {} times'.format(count))
else:
print('Mode: ')
print(lst[mxind])
print('The program looped {} times'.format(count))
find_mode([1, 2, 3, 5, 4, 9])

Screenshot:

Case 1: Multiple Modes:

Case 2: Single Mode:

Case 3: No Mode:

Values of lst, temp, temp1 (this is just for easier understanding of the code):