How To Create A Pipeline In Python

Your Guide To Productive Python Programming

Python gives us several valuable constructs to avoid repetition and to do more work with less code. Python is easy to replicate in Python by using list expansion after the initial positional arguments. The "two-variable swap trick" involves the use of tuples or the "multiple value input" trick that gets many variables from one line to one line. Python has a number of tricks to avoid mass repetition from writing a bunch of your own statements. It is better to use enumerate() in scenarios such as using len() to get both the length and the value and index for i... Additionally, avoid using value and avoid using index for value in syntax.

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@ zenulabidin
Ali Sherief

Admin at NotATether.com, developer at ChainWorks Industries & online entrepreneur

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.

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!

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 Stop Using Print to Debug in Python. Use Icecream Instead)

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.