Question

How do I merge a list of lists?

[['A', 'B', 'C'], ['D', 'E', 'F'], ['G', 'H', 'I']]

into

['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I']

Even better if I can add a value on the beginning and end of each item before merging the lists, like html tags.

i.e., the end result would be:

['<tr>A</tr>', '<tr>B</tr>', '<tr>C</tr>', '<tr>D</tr>', '<tr>E</tr>', '<tr>F</tr>', '<tr>G</tr>', '<tr>H</tr>', '<tr>I</tr>']

Answer 1

To concatenate the lists, you can use sum

values = sum([['A', 'B', 'C'], ['D', 'E', 'F'], ['G', 'H', 'I']], [])

To add the HTML tags, you can use a list comprehension.

html_values = ['<tr>' + i + '</tr>' for i in values]