import re
entities = ['blab', 'r1', 'zss']
sentences = ['this r1 is about zsse', 'this [r1] is about [zss]e']
new_sentences = []
for s in sentences:
for e in entities:
if re.search(r"\[%s\]" % e, s):
pass
else:
s=s.replace(e,'['+e+']')
new_sentences.append(s)
print(new_sentences)
aW1wb3J0IHJlCiAgICAgCmVudGl0aWVzID0gWydibGFiJywgJ3IxJywgJ3pzcyddCnNlbnRlbmNlcyA9IFsndGhpcyByMSBpcyBhYm91dCB6c3NlJywgJ3RoaXMgW3IxXSBpcyBhYm91dCBbenNzXWUnXQpuZXdfc2VudGVuY2VzID0gW10KICAgICAKZm9yIHMgaW4gc2VudGVuY2VzOgogICAgZm9yIGUgaW4gZW50aXRpZXM6CiAgICAgICAgaWYgcmUuc2VhcmNoKHIiXFslc1xdIiAlIGUsIHMpOgogICAgICAgICAgICBwYXNzCiAgICAgICAgZWxzZToKICAgICAgICAgICAgcz1zLnJlcGxhY2UoZSwnWycrZSsnXScpCiAgICBuZXdfc2VudGVuY2VzLmFwcGVuZChzKQogICAgIApwcmludChuZXdfc2VudGVuY2VzKQ==