10.2 Finding the Longest Protein

This was another problem that most people seemed to have trouble with. So, I thought that I would also present two approaches for this question:

10.2.1 Approach #1: a linear search

Here, we will declare a variable longest that captures the sublist with the longest protein. For no particular reason, I assume that the first sublist of many_lists_copy has the longest protein; I then used a for loop to iterate through many_lists_copy to find the sublist with the longest protein.

longest = many_lists_copy[0]   

for i in many_lists_copy: 
  if len(i[-1]) > len(longest[-1]): 
    longest = i 

print(f"The longest protein has accession {longest[0]} and length {len(longest[-1])}")

Note that many_lists_copy’s sublists also have the same structure as the sublists in many_lists!

10.2.2 Approach #2: Using sorted()

The sorted() function returns the sorted version of a list. Depending on what you want to do with the accession IDs and the associated protein lengths, the sorted() function may be ideal.

Nevertheless, I use an anonymous function to sort many_lists_copy by their protein lengths in reverse order (specified by the reverse = True argument):

longest = sorted(many_lists_copy, key = lambda x : len(x[-1]), reverse = True)[0]

print(f"The longest protein has accession {longest[0]} and length {len(longest[-1])}")

I then chose the first sublist returned by the sorted() function!