Supercharge your Python programming with these tricks
Tags: python
Published: 2021-04-26 10:08:39

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.

```python
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](https://link.medium.com/2WJD5ChxGfb))

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

```python
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?

```python
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.

```python
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.
```python
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!

```python
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.

```python
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.

---

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.