Python Program to extracts elements from the list with digits in increasing order

Given List of elements, extract all elements which have digits that are increasing in order.

Input : test_list = [1234, 7373, 3643, 3527, 148, 49] 
Output : [1234, 148, 49] 
Explanation : All elements have increasing digits.
Input : test_list = [12341, 7373, 3643, 3527, 1481, 491] 
Output : [] 
Explanation : No elements have all increasing digits. 

Method 1 : Using loop and str()

In this, we convert each element to string and then check if their each digit is greater than previous one using loop.

Python3

# initializing list
test_list = [1234, 7373, 3643, 3527, 148]

# printing original list
print("The original list is : " + str(test_list))

# loop to check for each element
res = []
for ele in test_list:
    flag = True

    for idx in range(len(str(ele)) - 1):

        # checking for each next digit
        if str(ele)[idx + 1] <= str(ele)[idx]:
            flag = False

    if flag:
        res.append(ele)

# printing result
print("Extracted increasing digits : " + str(res))

Output:

The original list is : [1234, 7373, 3643, 3527, 148]
Extracted increasing digits : [1234, 148]

Method 2 : Using sorted(), list comprehension and str()

In this, we test for each digit of an element to be increasing by sorting each element and compare it with original version. If they are same, the element is added to desired list.

Python3

# initializing list
test_list = [1234, 7373, 3643, 3527, 148]

# printing original list
print("The original list is : " + str(test_list))

# sorting and comparing for equality
res = [ele for ele in test_list if ''.join(sorted(str(ele))) == str(ele)]

# printing result
print("Extracted increasing digits : " + str(res))

Output:

The original list is : [1234, 7373, 3643, 3527, 148]
Extracted increasing digits : [1234, 148]