How to join() words from a string?

Question

I want to transform the string 'one two three' into one_two_three.

I've tried "_".join('one two three'), but that gives me o_n_e_ _t_w_o_ _t_h_r_e_e_...

how do I insert the "_" only at spaces between words in a string?

Answer 1

You can use string's replace method:

'one two three'.replace(' ', '_')
# 'one_two_three'

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str.join method takes an iterable as an argument and concatenate the strings in the iterable, string by itself is an iterable so you will separate each character by the _ you specified, if you directly call _.join(some string).

Answer 2

You can also split/join:

'_'.join('one two three'.split())

Answer 3

And if you want to use join only , so you can do like thistest="test string".split() "_".join(test) This will give you output as "test_string".