List with duplicated values and suffix

Question

I have a list, a:

a = ['a','b','c'] 

and need to duplicate some values with the suffix _ind added this way (order is important):

['a', 'a_ind', 'b', 'b_ind', 'c', 'c_ind'] 

I tried:

b = [[x, x + '_ind'] for x in a] c = [item for sublist in b for item in sublist] print (c) ['a', 'a_ind', 'b', 'b_ind', 'c', 'c_ind'] 

Is there some better, more pythonic solution?

Answer 1

You could make it a generator:

def mygen(lst):     for item in lst:         yield item         yield item + '_ind'  >>> a = ['a','b','c'] >>> list(mygen(a)) ['a', 'a_ind', 'b', 'b_ind', 'c', 'c_ind'] 

You could also do it with itertools.product, itertools.starmap or itertools.chain or nested comprehensions but in most cases I would prefer a simple to understand, custom generator-function.

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With python3.3, you can also use yield from—generator delegation—to make this elegant solution just a bit more concise:

def mygen(lst):     for item in lst:         yield from (item, item + '_ind')