RegEx XXI: Non-Capturing Groups

A non-capturing group will match "x" in (?:x), however the match won't be stored, meaning you won't be able to access it using backreference, and it won't be output separately when using re.findall().

Let's see an example of the difference between capturing and non-capturing groups:

txt = "red car, blue car, yellow car, green car, red car, red bike, blue bike"

pattern1 = "(red|blue) car"
pattern2 = "(?:red|blue) car"
pattern3 = "red|blue car"
pattern4 = "((red|blue) (car|bike))"
pattern5 = "((red|blue) (?:car|bike))"

re.findall(pattern1, txt) ➞ ["red", "blue", "red"]
re.findall(pattern2, txt) ➞ ["red car", "blue car", "red car"]
re.findall(pattern3, txt) ➞ ["red", "blue car", "red", "red"]
re.findall(pattern4, txt) ➞ [("red car", "red", "car"), ("blue car", "blue", "car"), ("red car", "red", "car"), ("red bike", "red", "bike"), ("blue bike", "blue", "bike")]
re.findall(pattern5, txt) ➞ [("red car", "red"), ("blue car", "blue"), ("red car", "red"), ("red bike", "red"), ("blue bike", "blue")]

• The first expression matches either "red" or "blue", as long as they're followed by " car".
• The second expression matches either "red car" or "blue car".
• The third expression matches either "red" or "blue car".
• In the fourth expression matches one of the following possibilities: "red car", "red bike", "blue car", "blue bike". It will return a tuple for each match containing an element for each capturing group, in this case: the whole expression, the color and the vehicle type.
• The fifth expression is similar to the fourth except the vehicle type is a non-capturing group. As you can see, it is not returned separately.

Write a regular expression to match any article + noun pair. The articles are either "a/an" or "the". Use non-capturing groups in your expression.

Example

txt = "There is an apple and a pen on the desk"
pattern = "yourregularexpressionhere"

re.findall(pattern, txt) ➞ ["an apple", "a pen", "the desk"]

Notes

• You don't need to write a function, just the pattern.
• Do not remove import re from the code.
• You can find all the challenges of this series in my Basic RegEx collection.