for Loopsfor loops is a type of loop that allows us walking on the lists, tuples, strings, and even dictionaries.. The syntax of this loop is: for item in objectit can be a list, a tupl
Trang 1for Loops
for loops is a type of loop that allows us walking on the lists, tuples, strings, and even dictionaries The syntax of this loop is:
for item in object(it can be a list, a tuple, a dictionary etc.): statements
Here is a breakdown of the syntax:
for➜ the keyword that indicates that the for statement begins
item ➜ specifies the name of the variable that will hold a single element of a sequence
in ➜ indicates that the sequence comes next
object ➜ the sequence that will be stepped through
statements ➜ the statements that will be executed in each iteration
Walking on the lists:
In [1]: my_list = [1,2,3,4,5,6]
for element in my_list:
print("Item",element)
In [2]: # Adding elements using for loop
list1 = [1,2,3,4,5,6]
sum = 0
for item in list1:
sum = sum + item print("Sum =",sum)
Item 1
Item 2
Item 3
Item 4
Item 5
Item 6
Sum = 21
Trang 2In [3]: # Printing even numbers
list2 = [1,2,3,4,5,6,7,8]
for item in list2:
if item % 2 == 0:
print(item)
In [4]: # Printing odd numbers
list2 = [1,2,3,4,5,6,7,8]
for item in list2:
if item % 2 == 1:
print(item)
Walking on the strings:
In [5]: s = "Hello world!"
for letter in s:
print(letter)
In [6]: # Replicate strings using loops
s = "Python"
for letter in s:
print(letter * 5)
2
4
6
8
1
3
5
7
H
e
l
l
o
w
o
r
l
d
!
PPPPP
yyyyy
ttttt
hhhhh
ooooo
nnnnn
Trang 3In [7]: # Walking on the tuples
t = (1,2,3,4,5,6)
for item in t:
print(item)
We can walkthrough the multidimensional tuples like this:
In [8]: # Two-dimensional tuples
list3 = [(1,2),(3,4),(5,6),(7,8)]
for item in list3:
print(item)
We can see that each element is printed as tuple What if we want to reach that items?
In [9]: # Tuple unpacking
list3 = [(1,2),(3,4),(5,6),(7,8)]
for (i,j) in list3:
print("i:",i,"j:",j)
In [10]: #Unpacking three dimensional tuples
list4 = [(1,2,3),(4,5,6),(7,8,9),(10,11,12)]
for (i,j,k) in list4:
print(i * j * k)
Walk through the dictionaries:
We have learned 3 methods of the dictionaries in our dictionaries lesson
1) keys() method
2) values() method
3) items() method
1
2
3
4
5
6
(1, 2)
(3, 4)
(5, 6)
(7, 8)
i: 1 j: 2
i: 3 j: 4
i: 5 j: 6
i: 7 j: 8
6
120
504
1320
Walking on the tuples:
Trang 4In [11]: my_dict = {"one":1,"two":2,"three":3,"four":4}
my_dict.keys()
In [12]: my_dict.values()
In [13]: my_dict.items()
We can walk through the dictionaries with using these methods
If we don't write any dict methods, we get keys of the dictionary as default
Let's see this:
In [14]: dict1 = {"one":1,"two":2,"three":3,"four":4}
for i in dict1:
print(i)
In [15]: #using keys method
dict1 = {"one":1,"two":2,"three":3,"four":4}
for i in dict1.keys():
print(i)
In [16]: #using values method
dict1 = {"one":1,"two":2,"three":3,"four":4}
for i in dict1.values():
print(i)
In [17]: #using items method
dict1 = {"one":1,"two":2,"three":3,"four":4}
for i in dict1.items():
print(i)
Out[11]: dict_keys(['one', 'two', 'three', 'four'])
Out[12]: dict_values([1, 2, 3, 4])
Out[13]: dict_items([('one', 1), ('two', 2), ('three', 3), ('four', 4)])
one
two
three
four
one
two
three
four
1
2
3
4
('one', 1)
('two', 2)
('three', 3)
('four', 4)
Trang 5In [18]: #getting the keys and values with items()
dict1 = {"one":1,"two":2,"three":3,"four":4}
for k,v in dict1.items():
print("Key:",k,"Value:",v)
This is the end of this lesson
See you in our next lessons
In [ ]:
Key: one Value: 1
Key: two Value: 2
Key: three Value: 3
Key: four Value: 4