Problem scenario
You want a function to tell you if there are three unique characters in a string. For example “ababababa” would have fewer than three unique characters. But “abc” would have three or more unique characters. How do you write a function that does this that solves in linear time?

Solution

variable_to_test = “aaaaaaaaaaaabbbbbb”

def two_unique(s):
flag = “There are only two unique characters in the string!”
dict_a = {}
for string_portion in s:
if string_portion in dict_a:
pass
else:
dict_a[string_portion] = 1
key_counter = 0
for key in dict_a.keys():
key_counter = key_counter + 1; …

Continue reading “How Do You Write a Python Function to Determine if There Are Three or More Unique Characters in a String?”

Problem scenario
List operations such as .sort() will change previous copies of the list.

String operations such as .replace(“old_pattern”, “new_pattern”, count), will not change the variable or its copies; these operations will return a string after the replace operation has run on the original string.

Why is this behavior happening?

Solution
In-place changes and mutability are factors. Strings are generally immutable whereas copies of lists are usually shallow.

…

Continue reading “Why Are Python List Operations/Methods Unlike Python String Operations/Methods?”

Problem scenario
You are running a Python script. You keep getting “SyntaxError: invalid syntax” and a line number. You can find nothing wrong with the syntax on the specified line number. What do you do?

Possible solution #1
Look at the line with code, as opposed to blank line(s), above it. Is there a missing quote, brace, bracket or parentheses?

Possible solution #2
Are you trying to use an “if” statement on one line?

…

Continue reading “How Do You Troubleshoot “SyntaxError: invalid syntax” in Python?”