Python: how to swap values of 2 iterators in 2 for loops?
I have a code that wants to run like this:
for i in range(10): for j in range(10): if a condition is satisfied: let i = j in the next loop, j is reset back to 0
i = 0, j = 0 and condition is not met => continue
i = 0, j = 1 and condition is met => let
i = j
i = 1, j = 0 then
i = 1, j = 1 and the loop continues.
More example: if
i = 3, j = 2 and condition is met:
i = 2, j = 3
There is not way of changing
i in the next for loop iteration. You have to use while loops:
i,j = 0,0 while i < 10: while j < 10: if a condition is satisfied: let i = j in the next loop, j is reset back to 0
matrix, I have a code that wants to run like this: for i in range(10): for j in range(10): if a condition is satisfied: let i = j in the next loop, j is reset back to 0. In Python, there is a simple construct to swap variables. The following code does the same as above but without the use of any temporary variable. x = 5 y = 10 x, y = y, x print("x =", x) print("y =", y)
i, j = 0, 0 while i < 10: while j < 10: if a condition is satisfied: i, j = j, i j += 1 i += 1
4. More Control Flow Tools — Python 2.7.18 documentation, Iterating over a sequence does not implicitly make a copy. Loop statements may have an else clause; it is executed when the loop 2 is a prime number 3 is a prime number 4 equals 2 * 2 5 is a prime number In fact, even functions without a return statement do return a value, albeit a rather boring one. 1 2 3 Traceback (most recent call last): File "<stdin>", line 2, in <module> StopIteration Which is almost what we want. But now my_iterator seems to be broken: It has reached the end of the list and can't go any further. Here's a little summary of what we have learned to far: For loops loop over iterables. iterables have __iter__ functions
You cannot use
range() since it will produce a generator, that doesn't care about the current (edited) value of
You can do what you seek like so with a while loop.
i = 0 j = 0 while(i < 10): j = 0 while(j < 10): if condition: i, j = j, i j += 1 i += 1
Python2 Tutorial: For Loops, Introduction into loops and the for Loop in Python. Content: Python 2 Tutorial In each iteration step a loop variable is set to a value in a sequence or other data As we mentioned earlier, the Python for loop is an iterator based for loop. the choice working with Python 2 or Python 3, we recomend to switch to Python 3! In order to swap two variables, we will require to use a temporary variable which will be helping us by storing the values temporarily. So that we can swap the values, we will need the values first. There are two ways of putting the values in the variable. Either we can assign the values or we can take values from the user while the program
itertools – Iterator functions for efficient looping, Reducing memory usage can reduce swapping and other side-effects of large data In the first example, the lambda function multiplies the input values by 2. An iterator is an object representing a stream of data. It does the iterating over an iterable. You can use an iterator to get the next value or to loop over it. Once, you loop over an iterator, there are no more stream values. Iterators use the lazy evaluation approach. Many built-in classes in Python are iterators.
ProjPython – Lists and for-loops, some_numbers has the value 8 (remember, we start counting, or indexing, the list, from Iterating over a list with a while-loop for the first half of the items in the list: swap the item with the corresponding item from the second half of the list. Then you will learn about iterables and iterators, two concepts that form the basis of definite iteration in Python. Finally, you’ll tie it all together and learn about Python’s for loops. Free Download: Get a sample chapter from Python Tricks: The Book that shows you Python's best practices with simple examples you can apply instantly to
How to reverse a string in C++, //Note that it takes the iterators to the start and end of the string as arguments. 10 2. Using a loop. Within the main body of the function, a loop can be written to reverse a string. //Using the swap method to switch values at each index. 11. Comparing zip() in Python 3 and 2. Python’s zip() function works differently in both versions of the language. In Python 2, zip() returns a list of tuples. The resulting list is truncated to the length of the shortest input iterable. If you call zip() with no arguments, then you get an empty list in return: >>>
- Can you tell us what you’re trying to do with these loops? This seems like a case of the XY problem.
- I'm finding an Euler path using adjacency matrix using Python. The simplest case was a triangle ABC I can do that, but the rectangle ABCD it printed me the wrong result order, and when I debugged, i did not swap with j.
- Your indents are broken.
- are you missing this ->
j is reset back to 0?