Aravind Ramalingam
- Python
- Tuple
- List
Use case for Python Tuple
Most Python programmers are guilty (me included) of always using List without even considering Tuple at all. Surely for some use cases, Tuple should be better, right? Keep reading for one such case.
Tuple is like List but immutable, so it has lesser in built methods. Tuples are faster than Lists, but it is noticeable only when the size of the tuple is considerably large. If you want a refresher, check out this blog by Michael Galarnyk
Caveat
A general rule of thumb is to use Tuple only when the data will or should not change.
# Create Tuple with two elements
tup = (1, [2])
# Re-assign first element
tup[0] = 3
This does not mean you really can't change a tuple. If the underlying tuple element is mutable, then we can change it. This could lead to unintended side effects. For example, children/inherited class can modify a tuple element initialized by the parent class.
# Add element to existing List element inside Tuple
tup[1].append(3)
print(tup)
Use Case
Personally, I am more into Deep Learning and have to deal with image files a lot. Image files have many popular formats like jpg, png and svg etc. We often have a situation where we have to find all files of certain types from a folder. There are many ways of going about this. We will explore a few options.
Option 1: Using List
The filtering based on the extension type is done with the help of
endswith method. Since the
endswith method does not accept list,
we are looping through all the extension elements. The code looks
readable and takes about 2 microseconds which is not bad, but
for every extension type, we have to run through all the files one more
time. I have a suspicion that we can do much better.
Option 2: Using Tuple
Almost similar code, but we are able to pass the entire Tuple as
parameter to the endswith method. This
removes the extra loop and makes the code even shorter. The code now
runs about 2 times faster.
Conclusion
Some methods like startswith and
endswith accept Tuple as parameter, if
the data does not change then better to use Tuple or convert List to
Tuple before passing data to the method. Tuples make the code look more
elegant and run faster. Also, don't forget about the caveat.
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