Merge two strings with alternate chars as output

Question

I got the task to alternately combine the letters of two strings with the same length.

For example:

Inputstring 1: \"acegi\"

Inputstring 2: \"bdfhj\         


        

Answer 1

You can do it in one line using zip and join.

out1 = ''.join(''.join(f for f in tup) for tup in zip(inp1, inp2))

or the more functional-style:

out1 = ''.join(map(''.join, zip(inp1, inp2)))  # kudos @Coldspeed

which both print

abcdefghij

---

Braking the code down:

• zip()

  pairs = list(zip(inp1, inp2))
  print(pairs )  # [('a', 'b'), ('c', 'd'), ('e', 'f'), ('g', 'h'), ('i', 'j')]
  

• .join()

  temp = []
  for sub in pairs:
      temp.append(''.join(sub))
  print(temp)  # ['ab', 'cd', 'ef', 'gh', 'ij']
  

• .join() again

  out1 = ''.join(temp)
  print(out1)  # abcdefghij
  

---

Finally, and for your entertainment and learning only, two additional, more old-school approaches:

out1 = ''
for i in range(len(inp1)):
    out1 += inp1[i] + inp2[i]

and

out1 = ''
for i, c in enumerate(inp1):
    out1 += c + inp2[i]