How do you get x amounts of y in one string and put it in another string in python?

Question

If the string is "43 Lobsters and 3 Crabs" I want to get only the s's from this string. There are three s's so in my new string I must have just "sss".

Answer 1

Try this:

>>> strng = '43 Lobsters and 3 Crabs'
>>> ''.join([letter for letter in strng if letter == 's'])
'sss'

Here we use a simple list comprehension to iterate through the string, and check if each letter matches the letter s. This creates a list, and to make it into a string you just use the join function.

Answer 2

why dont you use the count function?

thestr = "43 Lobsters and 3 Crabs"
y = 's'
x = thestr.count(y)

so now you know how many times it appears in the string use that variable to construct a string

finstr = y * x

Answer 3

You can try iterating over the characters of the string and if the character equals s, you take it to build a string. At the end the string would be "sss" if there were 3 's' in the string.

Answer 4

Have you tried anything so far?

Try a for loop:

One line (called "List Comprehension"):

input_string = "43 Lobsters and 3 Crabs" # Input line
answer = "".join(["s" for letter in input_string if letter == "s"]) 
# List comprehension
# "".join is to combine the list into a string

print (answer) # Output
# It is in parenthesis because I do not know your Python version

# Returns sss

Usual for loop:

input_string = "43 Lobsters and 3 Crabs" # Input line
answer = "" # Answer to which we will add "s"s as needed
for letter in input_string: # For loop
    if letter == "s":
        answer += "s" # Adding "s" to final if it is an "s"

print (answer) # Output

# Returns sss

---

If you want it to be case insensitive, add .lower() to the input:

input_string = "43 Lobsters and 3 Crabs" # Input line
answer = "".join(["s" for letter in input_string.lower() if letter == "s"]) 

print (answer) # Output

# Returns sss regardless if it is capitalized or not

Or:

input_string = "43 Lobsters and 3 Crabs".lower() # Input line
answer = "".join(["s" for letter in input_string if letter == "s"]) 

print (answer) # Output

# Returns sss regardless if it is capitalized or not

---

And if you need to differentiate between capital and lowercase "s"s, try this. I will use "43 LobsterS and 3 CrabS" for input.

input_string = "43 LobsterS and 3 CrabS" # Input line
answer = ""
for letter in input_string:
    if letter == "s":
        answer += "s"
    elif letter == "S":
        answer += "S"

print (answer) # Output

# Returns sSS for "43 LobsterS and 3 CrabS"