Supercharge your Python programming with these tricks

Have you ever felt that you are not coding Python as productive as you want to be?

Have you ever found yourself repeating the same statements consecutively but each with slight changes?

Well then, is guide is for you. The beauty of Python is that it gives us several valuable constructs to avoid repetition and to do more work with less code.

You may already know such gems as what I call the "two-variable swap trick" involving the use of tuples or the "multiple value input” trick that gets many variables from input() by running the resulting line through split(" "), or even the one-liner fit reversing an array using [::-1], but this article will give you even more shortcuts to use.

Variable numbers of arguments

You might know that there are some C functions such as printf(), which take a variable number of arguments depending on the value of the first one. This is easy to replicate in Python by using list expansion after the initial positional arguments.

def fun1(*a):
    res=1
    for ele in a:
        res*=ele
    return res
ans=fun1(5,6,9,6,9,6,6)
print(ans)   # prints `524880`

(from 10 Python Tricks That Will Wow You)

Here's another more organic example, a calculator that makes use of positional arguments:

OP_ADD = 1
OP_SUBTRACT = 2
OP_MULTIPLY = 3
#...
def calculator(op, *var):
    if op == OP_ADD:
        a, b = *var
        return a + b
    elif op == OP_NEG:
        a = *var
        return -a
    #...

Selectively printing text

Have you ever found yourself writing code like this?

if foo == True:
    print("All is well!")
else:
    print("We may have a problem")

You don't have to do that! This can be done in one line using the condensed form of the if statement.

print("All is well!" if foo == True else "We may have a problem")

Make a table of element occurrences

By making use of the count() method as a key, we can convert arrays to dictionaries to find how many times each element occurs.

li=[1,5,8,6,5,9,6,9,5,6,9,6,5,4,"a","a","b","b","a","a","a"]
di={k: li.count(k) for k in li}

Two-way comparisons

In Python, you can chain two less-than or greater-than operators to test whether a number is within a range. No more having to test them separately!

if 1 < x < 10:
   #...

Enhanced tracing using icecream

It's happened to most of us. The debugger goes kaput, and it forces us to sprinkle print() statements everywhere to trace program execution while finding a bug. Now seeing is everything, and most people can't write good words that help someone identify where control flow is (I know I can’t).

That's where icecream comes in handy. icecream is a PyPI module that contains a function you can place anywhere in the program, and when you call it without arguments, it will tell you the file and line number, as well as function it's in as well as the current time.

When you do call it with an argument, however, it will print the name and value of the variable you passed. It's convenient to avoid mass repetition from writing a bunch of your own print() statements.

from icecream import ic 

def hello(user:bool):
    if user:
        ic()
    else:
        ic()

hello(user=True)

num1 = 30
num2 = 40 

ic(num1)
ic(num2)

(from https://link.medium.com/v69x59YfHfb)

Antipatterns

Having said all that, make sure you avoid the following pitfalls while coding:

• Using list comprehensions on a vast array. This will use unnecessarily large amounts of memory.
• Using range(len(<list>)) for the iterator in for loops. This forces you to get the list length again using len(). It is better to use enumerate() in such scenarios to get both the value and index. Additionally, avoid using for i in ... syntax if you need indices in the loop.
• Using square brackets [] to access dictionary keys if they may not exist. Instead of handling KeyError exceptions (and it's tempting to omit try groups when accessing random dictionary keys), use the get() method of dictionaries, which will return None if the key does not exist. The resulting if conditional is much easier to handle in code.

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So as you just saw, Python is a very rich language that gives you more straightforward ways of programming the same thing. And where the functionality is not built-in, there is usually a PyPI module that does it.

Comments

[Daniel Diaz]

Good article!