[Python] Summary of how to use split and join functions

[Python] Summary of how to use split and join functions

1. [split function](#split function)
2. [Split by blank (empty argument)](#Split by blank)
3. [Split by specified character](# Split by specified character)
4. [Specify the number of delimiters](#Specify the number of delimiters)
5. [rsplit function](#rsplit function)
6. [join function](#join function)
7. [Combine string list (default)](# Combine string list by default)
8. [Combine list of numbers](# Combine list of numbers)

split function

Divide the character string by the specified characters to make a list.

Object .split ("split character ") └ Characters in the argument are deleted └ Object is a character string * Numerical value is an error └ Not destructive * The original object remains as it is └ If the argument is empty, split it with a space

Split with whitespace

s="1 2 3 4 5 6"

l = s.split()
print(l)

#output
['1', '2', '3', '4', '5', '6']

Specify a space as an argument

s="1 2 3 4 5 6"

l = s.split(" ")
print(l)

#output
['1', '2', '3', '4', '5', '6']

error

i=123456
l = i.split()

AttributeError: 'int' object has no attribute 'split'

python

s="1,2,3,4,5,6"
l = s.split(",")
print(l)

#output
['1', '2', '3', '4', '5', '6']

text

s="I have a pen !"
l = s.split()
print(l)

#output
['I', 'have', 'a', 'pen', '!']

Delimiter removed

s="I have a pen !"
l = s.split("a")
print(l)

#output
['I h', 've ', ' pen !']

split ('separator', integer) └ Divide into integers └ Maximum index number becomes an integer

python

s="1 2 3 4 5 6"
l = s.split(" ",2)
print(l)

#output
['1', '2', '3 4 5 6']

Element specification

s="1 2 3 4 5 6"
l = s.split(" ",2)

print(l[0])
print(l[2])

#output
1
3 4 5 6

Output the 0th element and the 2nd element. l [3] is out of range (IdexError: list index out of range)

rsplit ('separator', integer) └ Separate from the back by an integer └ Maximum index number becomes an integer

python

s="1 2 3 4 5 6"

ls = s.split(" ", 2)
lr = s.rsplit(" ", 2)
print(ls)
print(lr)

#output
['1', '2', '3 4 5 6']
['1 2 3 4', '5', '6']  #rsplit separates from behind

Extracting elements

s="1 2 3 4 5 6"

ls = s.split(" ", 2)
lr = s.rsplit(" ", 2)

#Output the 0th element
print(ls[0])
print(lr[0])

#output
1
1 2 3 4

No number of delimiters specified

s="1 2 3 4 5 6"

ls = s.split()
lr = s.rsplit()
print(ls)
print(lr)

#output
['1', '2', '3', '4', '5', '6']
['1', '2', '3', '4', '5', '6']

'Join character'.join (list) └ The element of list is a character string └ An error will occur if the element is not a character string └ Not destructive (object remains intact)

Combine list of strings (default)

python

l = ['I', 'have', 'a', 'pen', '!']

#「-Combine with
s1 = "-".join(l)
print(s1)

#Combine with whitespace
s2 = " ".join(l)
print(s2)

#output
I-have-a-pen-!
I have a pen !

** ▼ An error will occur if the element is not a character string **

python

l=[1,2,3,4]
s = "-".join(l)

#output
TypeError: sequence item 0: expected str instance, int found

(1) Convert to a character string with the map function. (2) Convert to a character string with a for statement.

(1) Convert to a character string with the map function

Convert elements from numbers to strings with the map function and join them with join.

python

l=[1,2,3,4]

ls = map(str, l)
s = "-".join(ls)
print(s)

#output
1-2-3-4

map (processing, iterable) -Perform processing one for each element of iterable. -If you specify a type for processing, you can convert to that type. -Output is map type (example: <map at 0x2d00fce8b80>) ・ Not destructive.

** ▼ Convert to a character string with map ** map (str, iterable)

Convert the numbers in list to strings

l=[1,2,3,4]

s = map(str, l)
print(list(s))

#output
['1', '2', '3', '4']

python

l=[1,2,3,4]

s = "-".join([str(i) for i in l])
print(s)

#output
1-2-3-4

・ Inclusive notation [Processing for Variables in Iterable] └ The processing result is returned as a list.