Python tutorial 32 --- "Join Function in Python"

We are all familiar with the word join and it's meaning i.e., to combine. Join has nearly the same meaning in Python, as it is used to join the elements of a list, tuple, set, etc. In this article, we will learn about the join() method and how to use it. In Python, join() is a function that is used with iterables like list, dictionaries, and string. Examples are also mentioned below so you may learn how to use join() function. If you do not know what iterables are, then check our tutorials on Python Lists And List Functions, Dictionary & It's Functions and String Slicing And Other Functions to get the basic idea about iterables.

What is the join method in Python?

"Join is a function in Python, that returns a string by joining the elements of an iterable, using a string or character of our choice."

In the case of join function, the iterable can be a list, dictionary, set, tuple, or even a string itself. The string that separates the iterations could be anything. It could just be a comma or a full-length string. We can even use a blank space or newline character (/n ) instead of a string.

The syntax of the join() method is:

string.join(iterable)

the string is the name of string in which joined elements of iterable will be stored.

Note: If the iterable contains any non-string values, join() will raise a TypeError exception.

The implementation over the list iterable example is explained below. Here we join the elements of a list using a delimiter. A delimiter can be any character or nothing.

For Example:

#join() with lists
numList = ['1', '2', '3', '4']
separator = ', '
print(separator.join(numList))

Output:

1, 2, 3, 4

With the join function, we can join two strings together, changing it into a larger string. Along with the iterable, we also have to use a string between each iterable and a string on its own is also iterable; thus, two strings can also be joined by using the join function.
It's is a lot easier and more compact than using a loop. We use a variable for iteration along with a string or fstring to print all the elements onto the screen.

How will the join function work in case of a "dictionary"? Are there any limitations to join() function?

The join function has certain limitations. We must have a question in our mind that how will join function will work in case of a "dictionary" where there are values along with the keys. In the case of the dictionary, the join function will only return the key part, separated by the string in between, leaving the value side behind.

For Example:

myDictionary = {"name": "Jack", "country": "America"}
separator = "_separator_"
print(separator.join(myDictionary))

Output:

name_separator_country

As we are on the subject, let us discuss another limitation associated with the join method. In situations where the iterable consists of a multi-data type, such as a list or tuple consisting of all integer variables and one single, double variable, the join function will not work. Instead, it will display an error. For join to function properly, all the variables should have the same sort of data type, either it is an integer, string, or any other.

For Example:

inputlist = ["Test1",13,"Test2",24,"Test3",100,"Test4"]
sep = '_'
out = sep.join(inputlist)
print(out)

Output:

Traceback (most recent call last): File "./prog.py", line 3, in TypeError: sequence item 1: expected str instance, int found

CODE-

# Join Function In Python

list1 = ["Rogers", "Stark", "Thor", "Romanoff", "Barton", "Banner"]

# Normal Method
for item in list1:
    print(item, ",", end=" ")
print(" and other Avengers")

# Using Join Function
a = ", ".join(list1)

print(a, "and other Avengers")