Tools you can use to avoid using for-loops
- List Comprehension / Generator Expression. Let’s see a simple example. ...
- Functions. Thinking in a higher-order, more functional programming way, if you want to map a sequence to another, simply call the map function.
- Extract Functions or Generators. The above two methods are great to deal with simpler logic. ...
- Don’t write it yourself. ...
Full Answer
Are loops in Python a bad idea?
Loops are not a bad idea. It is just that loop-intensive code canbe slow. But it is nothing specific to the loops, it is just that Python is not as fast in general as some other languages. I suggest you do not avoid loops if they are the most natural expression of your algorithm.
Do we need explicit FOR-loops in Python?
This article provides several alternatives for cases, IMHO, don’t need explicit for-loops, and I think it’s better not writing them, or at least, do a quick mental exercise to think of an alternative. There are several ways to re-write for-loops in Python.
Should I avoid loops in my algorithm?
I suggest you do not avoid loops if they are the most natural expression of your algorithm. If your code turns out slower of what you expect or need, then look for ways of optimizing it (profiling, to start with). The articleon Analysis of Algorithms in Wikipedia might me useful for you.
Why are nested loops bad for programming?
Nested loops are not a bad thing per se. They are only bad, if there are used for problems, for which better algorithm have been found (better and bad in terms of efficiency regarding the input size). Sorting of a list of integers for example is such a problem. In your case above you have three lists, all of size 4.
How do you avoid multiple loops in Python?
5 Ways To Break Out of Nested Loops in Python. Not as elegant as it should be. ... Add a Flag Variable. This is an effective solution. ... Raise an Exception. If we can't use the break keyword as expected. ... Check the Same Condition Again. ... Use the For-Else Syntax. ... Put It Into a Function.
How do you stop a for loop repeating in Python?
In Python, the break statement provides you with the opportunity to exit out of a loop when an external condition is triggered. You'll put the break statement within the block of code under your loop statement, usually after a conditional if statement.
How do I get out of multiple loops?
Breaking out of two loopsPut the loops into a function, and return from the function to break the loops. ... Raise an exception and catch it outside the double loop. ... Use boolean variables to note that the loop is done, and check the variable in the outer loop to execute a second break.
Does break in Python stop all loops?
The break statement in Python terminates the current loop and resumes execution at the next statement, just like the traditional break found in C. The most common use for break is when some external condition is triggered requiring a hasty exit from a loop. The break statement can be used in both while and for loops.
Does Break stop all loops?
In a nested loop, a break statement only stops the loop it is placed in. Therefore, if a break is placed in the inner loop, the outer loop still continues. However, if the break is placed in the outer loop, all of the looping stops.
How do you call a function only once in Python?
“run function just once python” Code Answerrun_once = 0.while 1:if run_once == 0:myFunction()run_once = 1:
Does Break exit if statement?
break does not break out of an if statement, but the nearest loop or switch that contains that if statement. The reason for not breaking out of an if statement is because it is commonly used to decide whether you want to break out of the loop .
How do you avoid nested for loops?
There is also a way to avoid nested loops by itertools. product() . You can use itertools. product() to get all combinations of multiple lists in one loop, and you can get the same result as nested loops.
What can I use instead of a break in Python?
Continue is also a loop control statement just like the break statement. continue statement is opposite to that of break statement, instead of terminating the loop, it forces to execute the next iteration of the loop. As the name suggests the continue statement forces the loop to continue or execute the next iteration.
How do you prevent a loop in a loop?
The complexity of having nested loops in your case is O(n * m) - n the length of orderArr , and m the length of myArr . This solution complexity is O(n + m) because we're creating the dictionary object using Array#reduce with complexity of O(m), and then filtering the orderArray with a complexity of O(n).
Try Using Dictionary Comprehension
Also try using dictionary comprehension, which is a relatively new addition in Python. The syntax is pretty similar to List comprehension.
Conclusion
To conclude, I will say that while it might seem easy to transfer the knowledge you acquired from other languages to Python, you won’t be able to appreciate the beauty of Python if you keep doing that. Python is much more powerful when we use its ways and decidedly much more fun.
Avoid for loops like plague
Your code will be much more readable and maintainable in the long run.
Tools you can use to avoid using for-loops
Let’s see a simple example. Basically you want to compile a sequence based on another existing sequence:
Action
Look at your code again. Spot any places that you wrote a for-loop previously by intuition. Think again and see if it make sense to re-write it without using for-loop.
setup
Lets take a pretty simple example where we are using a ficticious library to get some sales data for our transportation company. The api allows us to fetch teh sales data for one class of vehicle and one region at a time.
itertools.product
Python provides us with the beautiful itertools module that allows us to prepare our inputs for this in a much more susynct manner. The product function of itertools will give us every combination of any number of iterables
itertools.procuct for loop
Now that we have every comination of our two sets of inputs in a single list, we can iterate over that list one time.
itertools.product list comprehension
The above follows a python anti-pattern, initialize then edit. In some cases it might be a bit more readable to do it that way, you can be the judge, but in our simple case we can simply achieve the same results using a list comprehension.
Introduction
The for loop; commonly a key component in our introduction into the art of computing. The for loop i s a versatile tool that is often used to manipulate and work with data structures. For many operations, you can use for loops to achieve quite a nice score when it comes to performance while still getting some significant operations done.
Conclusion
Of course, there are many more approaches one could have to this sort of problem. No solution is better than another in all applications, I think that there is strength to each one of these different tools.