I want to do something like this.
example_string = "test"
print(example_string.replace(example_string[0], "b"))
expecting the output
best
however because the letter "t" is being passed into the method the t at the end also gets replaced with a "b". Resulting in the output
besb
How do I do it in a way that would result in the output "best" instead of "besb"?
The problem is that .replace(old, new) returns a copy of the string in which the occurrences of old have been replaced with new.
Instead, you can swap the character at index i using:
new_str = old_str[:i] + "b" + old_str[i+1:]
Check the documentation.
You can use
example_string.replace(example_string[0], "b", 1)
though it would be much more natural to use a slice to replace just the first character, as @nbryans indicated in a comment.
example_string[3]?
replace() where it is not appropriate, then. As noted, use slices when you want to act upon a particular location of a string (or other sequence such as a list or tuple). So for your new question: s = example_string[:3] + "b" + example_string[4:]example_string.replace("t", "b", 1)
example_string[3]?
new_str = "b" + example_string[1:].replace(a,b)is used for swapping all occurrences of stringawithb.word = "test"; i = word.index('t', 2); word[0:i] + "b" + word[i+1:]. Of course if you know the id of the char you want to replace instead of a letter you can directly set the variablei. If you need to substitue strings you could adapt it using thei+len(substring)+1to determine where the string ends.