{"id":118342,"date":"2020-09-22T13:17:19","date_gmt":"2020-09-22T13:17:19","guid":{"rendered":"https:\/\/blog.finxter.com\/?p=13555"},"modified":"2020-09-22T13:17:19","modified_gmt":"2020-09-22T13:17:19","slug":"56-python-one-liners-to-show-off-your-python-superpower","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/09\/22\/56-python-one-liners-to-show-off-your-python-superpower\/","title":{"rendered":"56 Python One Liners to Show Off Your Python Superpower"},"content":{"rendered":"

This is a running document in which I’ll answer all questions regarding the single line of Python code. It’s based on my interactive collection here but without the slow videos and embedded code shells. <\/p>\n

But before we move on, I’m excited to present you my brand-new Python book Python One-Liners<\/a><\/strong> (Amazon Link).<\/p>\n

If you like one-liners, you’ll LOVE the book. It’ll teach you everything there is to know about a single line of Python code.<\/strong> But it’s also an introduction to computer science<\/strong>, data science, machine learning, and algorithms. The universe in a single line of Python!<\/em><\/strong><\/p>\n

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\"\"<\/a><\/figure>\n<\/div>\n

The book is released in 2020 with the world-class programming book publisher NoStarch Press (San Francisco).<\/p>\n

Let’s get started!<\/p>\n

Python One Line If Else<\/h2>\n

You can use a simple if statement in a single line of code. This is called the ternary operator. The most basic ternary operator<\/a> x if c else y<\/code> returns expression x<\/code> if the Boolean expression c<\/code> evaluates to True<\/code>. Otherwise, if the expression c<\/code> evaluates to False<\/code>, the ternary operator returns the alternative expression y<\/code>.<\/p>\n

Here’s a minimal example:<\/p>\n

var = 21 if 3<2 else 42\nprint(var)\n# 42<\/pre>\n
\"Python<\/figure>\n
Ternary<\/strong> (from Latin ternarius<\/em>) is an adjective meaning “composed of three items”<\/em>. (source<\/a>) So, literally, the ternary operator in Python is composed of three operands.<\/p>\n
Syntax<\/strong>: The three operands are written as x if c else y<\/code> which reads as “return x<\/code> if c<\/code> else return y<\/code>“. Let’s write this more intuitively as:<\/p>\n
<OnTrue> if <Condition> else <OnFalse><\/pre>\n
\n\n\n\n\n\n\n\n
Operand<\/th>\nDescription<\/th>\n<\/tr>\n<\/thead>\n
<OnTrue><\/td>\nThe return expression of the operator in case the condition evaluates to True<\/code><\/td>\n<\/tr>\n
<Condition><\/td>\nThe condition that determines whether to return the <On True> or the <On False> branch.<\/td>\n<\/tr>\n
<OnFalse><\/td>\nThe return expression of the operator in case the condition evaluates to False<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>
Operands of the Ternary Operator<\/em><\/figcaption><\/figure>\n
Related Tutorial<\/strong>: The Ternary Operator in Python — Everything You Need to Know<\/a><\/p>\n
Python One Line Elif<\/h2>\n
\"Python<\/figure>\n
By now, you’ve learned how to write the if-else statement in a single line of code<\/a> using the ternary operator. But can you do the same with an elif statement if you have multiple conditions?<\/p>\n
Of course, you can! (If you’re in doubt about whether you can do XYZ in a single line of Python, just assume that you can. Check out my new book “Python One-Liners”<\/a> to master the single line of code!)<\/p>\n
Say, you want to write the following if-then-else condition in a single line of code:<\/p>\n
>>> x = 42\n>>> if x > 42:\n>>> print(\"no\")\n>>> elif x == 42:\n>>> print(\"yes\")\n>>> else:\n>>> print(\"maybe\")\nyes<\/pre>\n
The elif branch wins: you print the output \"yes\"<\/code> to the shell. But how to do it in a single line of code? Just use the ternary operator with an elif statement won’t work (it’ll throw a syntax error).<\/p>\n
The answer is simple: nest two ternary operators like so:<\/p>\n
print(\"no\") if x > 42 else print(\"yes\") if x == 42 else print(\"maybe\")\n# yes<\/pre>\n
If the value x is larger than 42, we print “no” to the shell. Otherwise, we execute the remainder of the code (which is a ternary operator by itself). If the value x is equal to 42, we print “yes”, otherwise “maybe”.<\/p>\n
So by nesting multiple ternary operators, we can greatly increase our Python one-liner power<\/a>!<\/p>\n
Related Article<\/strong>: Python Ternary Elif<\/a><\/p>\n
Now, you know how you can add more conditions to a single-line conditional statement. An interesting question is whether you can also add fewer conditions?<\/p>\n
Python One Line If Without Else<\/h2>\n
Problem<\/strong>: What’s the one-liner equivalent of the simple if statement without an else branch?<\/p>\n
Here’s an example:<\/p>\n
condition = True if condition: print('hi') # hi<\/pre>\n
You may want to (i) print something, (ii) assign a value to a variable, or (iii) append an element to a list if the condition holds.<\/p>\n
Next, I’ll show you four methods of how to accomplish this goal. All four methods are generally applicable—and you can easily customize them to your specific application.<\/p>\n
Let’s have a quick overview of the four methods:<\/p>\n
condition = True # Simple 2-Liner Method\nif condition: print('hi') # Method 1: One-Liner If\nif condition: print('hi') # Method 2: Ternary with Dummy\nprint('hi') if condition else None # Method 3: Ternary with Dummy for Assignment\nx = 42 if condition else None # Method 4: Short circuiting\ncondition and print('hi')<\/pre>\n
Read more about these methods in my detailed blog article. <\/a><\/p>\n
Python One Line Function<\/h2>\n
The most Pythonic way to define a function in a single line is to (1) create an anonymous lambda function and (2) assign the function object to a variable name. You can then call the function by name just like any other regularly-defined function. For example, the statement f = lambda x: x+1<\/code> creates a function f<\/code> that increments the argument x<\/code> by one and returns the result: f(2)<\/code> returns 3<\/code>.<\/p>\n
Problem<\/strong>: How to define a function in a single line of Python code? Let’s explore this mission-critical question!<\/p>\n
Example<\/strong>: Say, you want to write the following function in a single line of code:<\/p>\n
def f(x): return str(x * 3) + '!' print(f(1))\n# 3! print(f('python'))\n# pythonpythonpython!<\/pre>\n
Solution<\/strong>: Let’s get a quick overview of how to accomplish this first:<\/p>\n
##############################\n# Method 1: Single-Line Def\n##############################\ndef f1(x): return str(x * 3) + '!' print(f1(1))\nprint(f1('python')) ##############################\n# Method 2: Lambda Function\n##############################\nf2 = lambda x: str(x * 3) + '!' print(f2(1))\nprint(f2('python')) ##############################\n# Method 3: exec()\n##############################\nf3 = \"def f(x):\\n return str(x * 3) + '!'\" exec(f3 + '\\nprint(f(1))')\nexec(f3 + \"\\nprint(f('python'))\")\n<\/pre>\n
Can you figure out the output? You can check your understanding in the following article:<\/p>\n
Related Article<\/strong>: 3 Pythonic Ways to Define a Function in One Line [for Hackers]<\/a><\/p>\n
Python One Line For Loop<\/h2>\n
Python is powerful — you can condense many algorithms into a single line of Python code. So the natural question arises: can you write a for loop in a single line of code? This article explores this mission-critical question in all detail.<\/p>\n
How to Write a For Loop in a Single Line of Python Code?<\/strong><\/p>\n
There are two ways of writing a one-liner for loop:<\/p>\n