In Python, Function is a first-class object which means that function is just like any other object.
A function can be passed as argument, or you can include a function as an item in a list, or as a value in key:value pair of a dictionary, or item in a set, etc.
In this tutorial, we will learn how to add function[s] as item[s] in a list. In other words, we will build a list of functions.
Example
In this example, we define two functions named function1[] and function2[]. Then we will initialize a list with these two functions as items.
Python Program
def function1[]:
print['Function 1']
def function2[]:
print['Function 2']
myList = [function1, function2]We can also use the items of the list, which are functions, and call them. In the following program, we will use these list items and call the functions.
Python Program
def function1[]:
print['Function 1']
def function2[]:
print['Function 2']
#list of functions
myList = [function1, function2]
#call function using list object
myList[0][]
myList[1][]Output
Function 1
Function 2Note: Parenthesis after the function name calls the function, while just the function name gets the reference to the function.
Keeping in mind the above note, observe the Python program we wrote for this example. When we added functions to the list as items, we have not mentioned any parenthesis, just the function names. And when we wanted to call the function, we fetched the functions from the list using index, and used parenthesis. Parenthesis after function name called the function and executed it.
Summary
In this tutorial of Python Examples, we learned how to define a list with functions as items, and how to work with them.
This article was published as a part of the Data Science Blogathon
Introduction
In Python, you’ll be able to use a list function that creates a group that will be manipulated for your analysis. This collection of data is named a list object.
While all methods are functions in Python, not all functions are methods. There’s a key difference between functions and methods in Python. Functions take objects as inputs while Methods in contrast act on objects.
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Python offers the subsequent list functions:
- sort[]: Sorts the list in ascending order.
- type[list]: It returns the class type of an object.
- append[]: Adds one element to a list.
- extend[]: Adds multiple elements to a list.
- index[]: Returns the first appearance of a particular value.
- max[list]: It returns an item from the list with a max value.
- min[list]: It returns an item from the list with a min value.
- len[list]: It gives the overall length of the list.
- clear[]: Removes all the elements from the list.
- insert[]: Adds a component at the required position.
- count[]: Returns the number of elements with the required value.
- pop[]: Removes the element at the required position.
- remove[]: Removes the primary item with the desired value.
- reverse[]: Reverses the order of the list.
- copy[]: Returns a duplicate of the list.
List Refresher
It is the primary, and certainly the foremost common container.
- A list is defined as an ordered, mutable, and heterogeneous collection of objects.
- To clarify: order implies that the gathering of objects follow a particular order
- Mutable means the list can be mutated or changed, and heterogeneous implies that you’ll be able to mix and match any kind of object, or data type, within a list [int, float, or string].
- Lists are contained within a collection of square brackets [ ].
Image Source: Google Images
Let’s see all the functions one by one with the help of an example,
sort[] method
The sort[] method is a built-in Python method that, by default, sorts the list in ascending order. However, you’ll modify the order from ascending to descending by specifying the sorting criteria.
Example
Let’s say you would like to sort the elements of the product’s prices in ascending order. You’d type prices followed by a . [period] followed by the method name, i.e., sort including the parentheses.
Python Code:
type[] function
For the type[] function, it returns the class type of an object.
Example
In this example, we will see the data type of the formed container.
fam = ["abs", 1.57, "egfrma", 1.768, "mom", 1.71, "dad"] type[fam]
Output:
list
append[] method
The append[] method will add some elements you enter to the end of the elements you specified.
Example
In this example, let’s increase the length of the string by adding the element “April” to the list. Therefore, the append[] function will increase the length of the list by 1.
months = ['January', 'February', 'March'] months.append['April'] print[months]
Output:
['January', 'February', 'March', 'April']
extend[] method
The extend[] method increases the length of the list by the number of elements that are provided to the strategy, so if you’d prefer to add multiple elements to the list, you will be able to use this method.
Example
In this example, we extend our initial list having three objects to a list having six objects.
list = [1, 2, 3] list.extend[[4, 5, 6]] list
Output:
[1, 2, 3, 4, 5, 6]
index[] method
The index[] method returns the primary appearance of the required value.
Example
In the below example, let’s examine the index of February within the list of months.
months = ['January', 'February', 'March', 'April', 'May'] months.index['March']
Output:
2
max[] function
The max[] function will return the highest value from the inputted values.
Example
In this example, we’ll look to use the max[] function to hunt out the foremost price within the list named price.
prices = [589.36, 237.81, 230.87, 463.98, 453.42] price_max = max[prices] print[price_max]
Output:
589.36
min[] function
The min[] function will return the rock bottom value from the inputted values.
Example
In this example, you will find the month with the tiniest consumer indicator [CPI].
To identify the month with the tiniest consumer index, you initially apply the min[] function on prices to identify the min_price. Next, you’ll use the index method to look out the index location of the min_price. Using this indexed location on months, you’ll identify the month with the smallest consumer indicator.
months = ['January', 'February', 'March'] prices = [238.11, 237.81, 238.91]
# Identify min price min_price = min[prices] # Identify min price index min_index = prices.index[min_price] # Identify the month with min price min_month = months[min_index] print[min_month]
Output:
February
len[] function
The len[] function returns the number of elements in a specified list.
Example
In the below example, we are going to take a look at the length of the 2 lists using this function.
list_1 = [50.29] list_2 = [76.14, 89.64, 167.28] print['list_1 length is ', len[list_1]] print['list_2 length is ', len[list_2]]
Output:
list_1 length is 1 list_2 length is 3
clear[] function
The clear[] method removes all the elements from a specified list and converts them to an empty list.
Example
In this example, we’ll remove all the elements from the month’s list and make the list empty.
months = ['January', 'February', 'March', 'April', 'May'] months.clear[]
Output:
[ ]
insert[] function
The insert[] method inserts the required value at the desired position.
Example
In this example, we’ll Insert the fruit “pineapple” at the third position of the fruit list.
fruits = ['apple', 'banana', 'cherry']
fruits.insert[2, "pineapple"]Output:
['apple', 'banana', 'pineapple', 'cherry']
count[] function
The count[] method returns the number of elements with the desired value.
Example
In this example, we are going to return the number of times the fruit “cherry” appears within the list of fruits.
fruits = ['cherry', 'apple', 'cherry', 'banana', 'cherry'] x = fruits.count["cherry"]
Output:
3
pop[] function
The pop[] method removes the element at the required position.
Example
In this example, we are going to remove the element that’s on the third location of the fruit list.
fruits = ['apple', 'banana', 'cherry', 'orange', 'pineapple'] fruits.pop[2]
Output:
['apple', 'banana', 'orange', 'pineapple']
remove[] function
The remove[] method removes the first occurrence of the element with the specified value.
Example
In this example, we will Remove the “banana” element from the list of fruits.
fruits = ['apple', 'banana', 'cherry', 'orange', 'pineapple'] fruits.remove["banana"]
Output:
['apple', 'cherry', 'orange', 'pineapple']
reverse[] function
The reverse[] method reverses the order of the elements.
Example
In this example, we will be reverse the order of the fruit list, so that the first element in the initial list becomes last and vice-versa in the new list.
fruits = ['apple', 'banana', 'cherry', 'orange', 'pineapple'] fruits.reverse[]
Output:
['pineapple', 'orange', 'cherry', 'banana', 'apple']
copy[] function
The copy[] method returns a copy of the specified list and makes the new list.
Example
In this example, we want to create a list having the same elements as the list of fruits.
fruits = ['apple', 'banana', 'cherry', 'orange'] x = fruits.copy[]
Output:
['apple', 'banana', 'cherry', 'orange']
This ends our discussion!
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