import re
s = 'python java php'
st = set(s.replace(' ', ''))
result = {e: [sub.start() for sub in re.finditer(e, s)] for e in st}
print(result)
print(result['p'])
print(result['a'])
'''
run:
{'y': [1], 'p': [0, 12, 14], 'h': [3, 13], 'a': [8, 10], 'n': [5],
't': [2], 'v': [9], 'j': [7], 'o': [4]}
[0, 12, 14]
[8, 10]
'''