Comparing string objects within a list - Python

Question

message = ["TS", "EE", "RE", "Z"]

So I'm trying to compare the characters within this list, and have conditions when some things arise such as if a value in the list for example "EE" is the same, it will return true and append a "Q" to separate the letters so the list looks like this

 message = ["TS", "EQ", "ER" "EZ"]

So I tried it normally without looping it works but when I loop it says string index out of range.

a = ''
a = message[1]
if a[0] == a[1]:
 print("True")
else:
 print("False")

When looping

for i in range(len(message)):
 a = ''
 a = message[i]
 if a[0] == a[1]:
 print("True")

What should I do? Turn it into a string first and work on it?

• Chinny84: Your problem is the last element is length 1 so you tried to access the the second element when there is no second element i.e. Out of index error
• jasonharper: Those a = '' lines are not accomplishing anything, since you replace the value of a on the next line.
• andy9775: For the last item in the array (the letter Z) there is no position 1 since the string only consists of 1 character.

Answer 1

Note that there is an element "Z" in the array (i.e. message[-1]) that has only one char in it.

def getIndex(message):
 for i in range(len(message)):
 a = message[i]
 if a[0] == a[1]:
 return i
index = getIndex(message)
tmp = message[index][1]
message[index][1] = 'Q'
for x in range(index+1, len(message)):
 tmp1 = message[x][0] 
 if len(message[x])==1:
 message[x][0] = tmp
 message[x][1] = tmp1
 return
 else:
 message[x][0] = tmp
 tmp = message[x][1]
 message[x][1] = tmp1