Nested Loops And Tuples

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Im trying to get my code to print out each value on a new

cats = ("Tiger","Lion","Cheetah")
canids = ("Dog","Wolf","Fox")
reptiles = ("Snake","Crocodile","Iguana")
animals = (cats, canids,reptiles)
for i in animals:
    for j in [0,-1]:
        print(i[j])

but when i run it it doesn't include the second values of the lists,

Tiger
Cheetah
Dog
Fox
Snake
Iguana

If you want to iterate over a range of index, you need to use range. Otherwise, i only takes the value 0 and -1.

for i in animals:
    for j in range(0, len(i)): # Note the use of `range` here
        print(i[j])

Although, since i is itself a tuple you can iterate over it directly. Here I renamed i to family for readability.

for family in animals:
    for animal in family:
        print(animal)

Both have the following output.

Tiger
Lion
Cheetah
Dog
Wolf
Fox
Snake
Crocodile
Iguana

How we can iterate through a Python list of tuples?, Easiest way is to employ two nested for loops. Outer loop fetches each tuple and inner loop traverses each item from the tuple. Inner print()  its not just the second value. you are iterating 0 and -1, that is the first and last element of your tuple index. Therefore, any elements in between are not even considered! – Keerthana Prabhakaran Sep 11 '18 at 18:14

j will be 0 and -1, i.e. the first and last value when indexing a list.

You could simply

cats = ("Tiger", "Lion", "Cheetah")
canids = ("Dog", "Wolf", "Fox")
reptiles = ("Snake", "Crocodile", "Iguana")
animal_lists = (cats, canids, reptiles)
for animal_list in animal_lists:
    for animal in animal_list:
        print(animal)

Loops and lists, Terminology. The important computer science terms in this document are. list; tuple; nested list (and nested tuple); sublist (subtuple) or slice a[i:j]; while loop  Easiest way is to employ two nested for loops. Outer loop fetches each tuple and inner loop traverses each item from the tuple. Inner print() function end=’ ‘ to print all items in a tuple in one line. Another print() introduces new line after each tuple.

You can chain different iterables

from itertools import chain
list(chain(*animals))

Output

['Tiger',
 'Lion',
 'Cheetah',
 'Dog',
 'Wolf',
 'Fox',
 'Snake',
 'Crocodile',
 'Iguana']

Addition in Nested Tuples - Python, Addition in nested tuples. # using isinstance() + zip() + loop + list comprehension. # function to perform task. def tup_sum(tup1, tup2):. if isinstance (tup1, ( list  Tuples can be nested. Tuples can contain other compound objects, including lists, dictionaries, and other tuples. Hence, tuples can be nested inside of other tuples. Sample Program Nesting tuples. Listing 1 shows the beginning of a Python script that . Creates two tuples. Nests them in a third tuple.

Most basic modification you can make to your code is simply changing these set of lines

for i in animals:
    for j in i:
        print(j)

Same concept others provided just minimal adjustments to what you already have.

Python 3 Notes: More on for Loops, As mentioned briefly in Tutorial 14, the for in loop is adaptive: you can use it with The .items() method on a dictionary induces a pseudo-list of (key, value) tuples. If you think a simple for loop is easy, nested for loops can be a bit difficult to  The original list is : [(4, (5, 'Gfg')), (7, (8, 6))] The unpacked nested tuple list is : [(4, 5, 'Gfg'), (7, 8, 6)] Method #2 : Using list comprehension + “ * ” operator Many times, there might be a case in which we don’t know the exact number of element in tuple and also the element count is variable among tuples.

Simple Nested Loops Join, Simple Nested Loops Join. For each tuple in the outer relation R, we scan the entire inner relation S. Cost: M + (pR * M) * N = 1000 + 100*1000*500 I/Os: 140  The Python Language Reference says: The for statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable objects … Each item, in turn, is assigned to the target list using the standard rules for assignments. You already know the standard rules for assignments.

Collections and Looping: Lists and for – A Primer for Computational , Tuples work much like lists—we can call len() on them and extract elements or slices with Loops and the blocks they control can be nested, to powerful effect:. The syntax for a nested while loop statement in Python programming language is as follows − while expression: while expression: statement(s) statement(s) A final note on loop nesting is that you can put any type of loop inside of any other type of loop. For example a for loop can be inside a while loop or vice versa. Example

Looping Through Multiple Lists - Python Cookbook [Book], Looping Through Multiple Lists Credit: Andy McKay Problem You need to loop If there are multiple list arguments, map returns a list consisting of tuples that  Note: Even though tuples are defined using parentheses, you still index and slice tuples using square brackets, just as for strings and lists. Everything you’ve learned about lists—they are ordered, they can contain arbitrary objects, they can be indexed and sliced, they can be nested—is true of tuples as well.

Comments
  • What do you expect for j in [0,-1]: to do?
  • its not just the second value. you are iterating 0 and -1, that is the first and last element of your tuple index. Therefore, any elements in between are not even considered!