PYTHON

python concatenate list of lists

sum([[1, 2, 3], [4, 5, 6], [7], [8, 9]],[])
# [1, 2, 3, 4, 5, 6, 7, 8, 9]

Concatenate List

sample_list1 = [0, 1, 2, 3, 4] 
sample_list2 = [5, 6, 7, 8] 
 
result = sample_list1 + sample_list2 
 
print ("Concatenated list: " + str(result))

concatenate list in python

# There are many methods to do list concatenation
# Method 01
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
for i in test_list2 :
    test_list1.append(i)
print(test_list1)

# Method 02
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
test_list3 = test_list1 + test_list2
print(test_list3)

# Method 03
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
res_list = [y for x in [test_list1, test_list2] for y in x]
print(res_list)

# Method 04
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
test_list1.extend(test_list2)
print(test_list1)

# Method 05
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
res_list = [*test_list1, *test_list2]
print(res_list)

# Method 6
import itertools
test_list1 = [1, 4, 5, 6, 5]
test_list2 = ['p', 'q', 'r', 's']
res_list = list(itertools.chain(test_list1, test_list2))
print(res_list)

python concatenate list of lists

x = [["a","b"], ["c"]]

result = sum(x, [])

how to concatenate all list inside list

>>> x = [["a","b"], ["c"]]
>>> [inner
...     for outer in x
...         for inner in outer]
['a', 'b', 'c']