Aside from storing data, dictionaries and lists can also make it easier to write clean code. They can replace cumbersome if/elif, match/case, and long ‘or’ chains with something simpler.
A list can be used to clean up and replace long chains of or operators in a boolean expression.
For example, here is statement that prints “I’m flying” when the status (of a presumed airplane) is a phase of flight:
if status == "takeoff" or status == "climb" or status == "cruise" or status == "descent" or status == "landing":
print("I'm flying")To replace the or chain, we can place all the statuses in a list and then test membership using the in operator:
flying = ["takeoff", "climb", "cruise", "descent", "landing"]
if status in flying:
print("I'm flying")Dictionaries can simplify and replace if/elif chains.
In the next example, a different message is printed for each phase of flight. The if/elif version looks like this:
if status == "takeoff":
message = "Zooming down the runway"
elif status == "climb":
message = "Climbing up with power"
elif status == "cruise":
message = "Nice and relaxed up here"
elif status == "descent":
message = "Almost there"
elif status == "landing":
message = "Touching down"To simplify this, a you can create a dictionary with status keys and message values. Then, to print the message, simply index the dictionary with the status:
status_messages = {"takeoff": "Zooming down the runway",
"climb": "Climbing up with power",
"cruise": "Nice and relaxed up here",
"descent": "Almost there",
"landing": "Touching down"}
message = status_messages[status]