Syntax: String Slicing

Getting a String Slice in Python

A very important skill when working with strings is the ability to take sections from a string that already exists and either use those sections by themselves, or combine them with other strings. In Python, a section of a string (a sub-string) is generally referred to as a string "slice". When you take a slice from a string it is also a string datatype.

The syntax for getting a string slice is similar to getting a character by its position and also uses bracket ([]) notation. The main difference is that you specify two indexes inside the square ([]) brackets (instead of one), separated by a colon (:):

print("Elbow grease"[2:5])

> bow

In the example above, the [2:5] is the range of the slice. It is the short-hand equivalent to getting the characters one-at-a-time and concatenating them:

material = "Elbow grease"
print(material[2] + material[3] + material[4])

> bow

Note that the slice does include the character at the first position, but does not include the character at the second position (material[2] is "b" and material[5] is " ").

Multiple slices can be concatenated together to effectively cut out part of a string:

material = "Elbow grease"
print(material[0:5] + material[6:12])

> "Elbowgrease"

When the slice starts at the beginning of a string, the first index can be left out:

print("Elbow grease"[:4])

> "Elbo"

Likewise, when the slice ends at the end of a string, the second index can be left out:

print("Elbow grease"[5:])

> " grease"

Leaving both out will duplicate the whole string:

print("Elbow grease"[:])

> "Elbow grease"

Like when working with single characters, negative indexes will start from the back:

print("Elbow grease"[-5:])

> "rease"

Practice: Slicing Strings

1. Create a variable named phrase, and assign it the value "Make a long story short.".

2. Using the phrase variable, print a slice from indexes 5 to 10 (not including 10).

3. Using the phrase variable, print a slice containing the word "long".

4. Using the phrase variable, print a slice containing the last 10 characters.

5. Using the phrase variable, print the entire string with all the "o"s sliced out.

   HINT*: Click here for a hint

   > "a lon"

   > "long"

   > "ory short."

   > "Make a lng stry shrt."

   SOLUTION*: Click here for an example solution

   phrase = "Make a long story short."
   print(phrase[5:10])
   print(phrase[7:11])
   print(phrase[-10:])
   print(phrase[:8] + phrase[9:14] + phrase[15:20] + phrase[21:])
   

When the above steps are completed, you are ready to move to the next exercise!