[Python] Concatenate Lists / Merge Lists in Python

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[Python] Concatenate Lists / Merge Lists in Python

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(1) Concatenating Lists with "+" Operator

(2) Utilizing the Extend() Method

(3) Applying the Itertools.chain() Function

(4) Native Method for List Concatenation (list.append())

(5) List Comprehension to concatenate lists

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(1) Concatenating Lists with "+" Operator:

# Sample Code 1

list1 = [10, 11, 12, 13, 14]

list2 = [20, 30, 40]

res = list1 + list2

print ("Concatenated List: " + str(res))

# Concatenated List: [10, 11, 12, 13, 14, 20, 30, 40]

(2) Utilizing the Extend() Method:

   Syntax: list.extend(iterable)

# Sample Code 2

list1 = [10, 11, 12, 13, 14]

list2 = [20, 30, 40]

list1.extend(list2)

print ("Concatenated List: ", list1)

# Concatenated List: [10, 11, 12, 13, 14, 20, 30, 40]

(3) Applying the Itertools.chain() Function:

# Sample Code 3

import itertools

list1 = [10, 11, 12, 13, 14]

list2 = [20, 30, 40]

res = list(itertools.chain(list1, list2))

print ("Concatenated List: " + str(res))

# Concatenated List: [10, 11, 12, 13, 14, 20, 30, 40]

(4) Native Method for List Concatenation (list.append()):

# Sample Code 4

list1 = [10, 11, 12, 13, 14]

list2 = [20, 30, 40]

for x in list2:

    list1.append(x)

print ("Concatenated List: ", list1)

# Concatenated List: [10, 11, 12, 13, 14, 20, 30, 40]

(5) List Comprehension to concatenate lists:

# Sample Code 5

list1 = [10, 11, 12, 13, 14]

list2 = [20, 30, 40]

res = [j for i in [list1, list2] for j in i]

print ("Concatenated List: " + str(res))

# Concatenated List: [10, 11, 12, 13, 14, 20, 30, 40]

// End