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simple string program doesent work, python

A friend of mine told me that she needs help with some homework, I owe her a favor so I said fine, why not. she needed help with a program that checks a sequence, if the sequence is made of the same 2 chars one after the other it will print "yes" (for example "ABABABAB" or "3$3$3$3:)
The program works fine with even length strings (for example "abab") but not with odd length one ("ububu")
I made the code messy and "bad" in purpose, computers is her worst subject so I don't want it to look obvious that someone else wrote the code
the code -
def main():
StringInput = input('your string here - ')
GoodOrBad = True
L1 = StringInput[0]
L2 = StringInput[1]
i = 0
while i <= len(StringInput):
if i % 2 == 0:
if StringInput[i] == L1:
i = i + 1
else:
GoodOrBad = False
break
if i % 2 != 0:
if StringInput[i] == L2:
i = i + 1
else:
GoodOrBad = False
break
if GoodOrBad == True:
print("yes")
elif GoodOrBad != True:
print("no")
main()
I hope someone will spot the problem, thanks you if you read everything :)

How about (assuming s is your string):
len(set(s[::2]))==1 & len(set(s[1::2]))==1
It checks that there is 1 char in the even locations, and 1 char in the odd locations.

a) Showing your friend bad and messy code makes her hardly a better programmer. I suggest that you explain to her in a way that she can improve her programming skills.
b) If you check for the character at the even position and find that it is good, you increment i. After that, you check if i is odd (which it is, since you found a valid character at the even position), you check if the character is valid. Instead of checking for odd position, an else should do the trick.

You can do this using two methods->
O(n)-
def main():
StringInput = input('your string here - ')
GoodOrBad = True
L1 = StringInput[0]
L2 = StringInput[1]
i = 2
while i < len(StringInput):
l=StringInput[i]
if(l==StringInput[i-2]):
GoodOrBad=True
else:
GoodOrBad=False
i+=1
if GoodOrBad == True:
print("yes")
elif GoodOrBad == False:
print("no")
main()
Another method->
O(1)-
def main():
StringInput = input('your string here - ')
GoodOrBad = True
L1 = set(StringInput[0::2])
L2 = set(StringInput[1::2])
if len(L1)==len(L2):
print("yes")
else:
print("no")
main()

There is a lot in this that I would change, but I am just showing the minimal changes to get it to work. There are 2 issues.
You have an off by one error in the code:
i = 0
while i <= len(StringInput):
# in the loop you index into StringInput
StringInput[i]
Say you have 5 characters in StringInput. Because your while loop is going from i = 0 to i < = len(StringInput), it is going to go through the values [0, 1, 2, 3, 4, 5]. That last index is a problem since it is off the end off StringInput.
It will throw a 'string index out of range' exception.
You need to use:
while i < len(StringInput)
You also need to change the second if to an elif (actually it could just be an else, but...) so you do not try to test both in the same pass of the loop. If you go into the second if after the last char has been tested in the first if it will go out of range again.
elif i % 2 != 0:
So the corrected code would be:
def main():
StringInput = input('your string here - ')
GoodOrBad = True
L1 = StringInput[0]
L2 = StringInput[1]
i = 0
while i < len(StringInput):
if i % 2 == 0:
if StringInput[i] == L1:
i = i + 1
else:
GoodOrBad = False
break
elif i % 2 != 0:
if StringInput[i] == L2:
i = i + 1
else:
GoodOrBad = False
break
if GoodOrBad == True:
print("yes")
elif GoodOrBad != True:
print("no")
main()

def main():
StringInput = input('your string here - ')
MaxLength = len(StringInput) // 2 + (len(StringInput) % 2 > 0)
start = StringInput[:2]
chained = start * MaxLength
GoodOrBad = chained[:len(StringInput)] == StringInput
if GoodOrBad == True:
print("yes")
elif GoodOrBad != True:
print("no")
I believe this does what you want. You can make it messier if this isn't bad enough.

Magic Square Python 3

Having problems with my code and cannot seem to fix it or know where i have gone wrong. any help will be appreciated.
it runs but doesn't go any further than the user inputting the text file name.
it is supposed to read the user input and from that read a text file and declare whether it is a magic puzzle or not, i wanted this to read 5x5 as well but i'm a bit lost on how to do it
column = 0
row = 0
data = []
def main():
file = input("Enter filename :")
while True:
try:
f = open(file+".txt","r")
break
except:
file = input("Enter filename :")
for line in f.readline():
numbers = line.split(' ')
cube = [int(x) for x in numbers]
is_magic(x)
def is_magic(x):
if not dupe(x) and check_sum(x):
print ('Valid')
else:
print ('Invalid')
def dupe(x):
if len(x) == len(set(x)):
return False
return True
def check_sum(x):
if vertical_check(x) and horizontal_check(x) and diagonal_check(x):
return True
return False
def vertical_check(x):
if sum(x[0:9:3]) == sum(x[1:9:3]) == sum(x[2:9:3]) == 15:
return True
return False
def horizontal_check(x):
if sum(cube[0:3]) == sum(cube[3:6]) == sum(cube[6:9]) == 15:
return True
return False
def diagonal_check(x):
if sum(cube[0:9:4]) == sum(cube[2:7:2]) == 15:
return True
return False
def writeFile(x):
f = open("VALID_"+x+".txt","w")
text = ""
for a in data:
for x in a:
text = text+str(x)+" "
text = text+"\n"
f.write(text)
f.close()
return
main()
'''
txt file 3x3
2 9 4
7 5 3
6 1 8

The break statement inside while True makes you break the loop.
while True:
try:
f = open(file+".txt","r")
break

the reason for the program being stuck is the break statement after opening the file. This break statement will exit the while loop, so the rest of the code will not be executed.
f = open(file+".txt","r")
break # <<<< remove this

Entering Values, and adding specific types

Trying to figure out how to work a list of user input integers into separate categories and adding those categories together, and I'm stuck. This is what I have so far:
def main():
again = 'y'
while again == 'y':
pos_values = []
neg_values = []
value = int(input("Please enter value: "))
if value > 0:
pos_values.append(value)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
elif value < 0:
neg_values.append(value)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
else:
print(sum.pos_values)
print(sum.neg_values)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
total = 0
all_values = neg_values + pos_values
print[all_values]
print(total + pos_values)
print(total + neg_values)
main()
I'm just a first year student with no prior experience, so please be gentle!

Once you fix the logic error pointed out by Mike Scotty, the other problems are really just syntax errors. sum.pos_values will give you AttributeError: 'builtin_function_or_method' object has no attribute 'pos_values' (because sum is a built-in function and so needs () not .); and print[all_values] will give you a syntax error (because print is also a built-in function and so needs () not []). Your original code doesn't store zeroes in either list: I haven't changed that. And the output format is a guess on my part.
def main():
again = 'y'
pos_values = []
neg_values = []
while again == 'y':
value = int(input("Please enter value: "))
if value > 0:
pos_values.append(value)
elif value < 0:
neg_values.append(value)
else: #edit: terminate also on 0 input
break
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
all_values = neg_values + pos_values
print(sum(all_values),all_values)
print(sum(pos_values),pos_values)
print(sum(neg_values),neg_values)

Do while loops have local variables in Python?

I am trying to use a while statement like so:
o = 0
while o == 0:
try:
n = int(raw_input("Which number do you want to begin with?"))
o = 1
except:
o = 0
print "Please use a valid number."
However, when I try to use variable n later, it gives me the "local variable 'n' referenced before assignment' UnboundLocalError. That means that n cannot be recognized as a variable in the def I am using, because it only exists in the while statement? Is this possible?
The whole code:
import time
from sys import argv
import os
os.system("cls")
print "Welcome to Number counter 2.0!"
a = True
def program():
global a
if a == False:
os.system("cls")
o = 0
while o == 0:
try:
n = int(raw_input("Which number do you want to begin with?"))
o = 1
except:
o = 0
print "Please use a valid number."
if n == "/historyKeep false":
if a == False:
print "Command historyKeep is already set to false."
else:
a = False
print "Command set successfully."
elif n == "/historyKeep true":
if a == True:
print "Command historyKeep is already set to true."
else:
a = True
print "Command set successfully."
if n == "/historyKeep false":
n = raw_input("Which number do you want to begin with?")
elif n == "/historyKeep true":
n = raw_input("Which number do you want to begin with?")
d = raw_input("How many seconds between each number?")
d = int(d)
total_s = n * d
while n > 0:
print n
time.sleep(d)
n = n - 1
print "Done in", total_s, "seconds in total!"
end_q = raw_input("Exit or retry? (e/r)")
if end_q == "e":
os.system("cls")
print "Exiting."
time.sleep(0.5)
os.system("cls")
print "Exiting.."
time.sleep(0.5)
os.system("cls")
print "Exiting..."
time.sleep(0.5)
os.system("cls")
exit(0)
elif end_q == "r":
program()
program()

You set a = True at the beginning. You then test if a == False and only set n if it is. But then you test n == "/history.... n has not been set at this point.
You need to make sure n is assigned before you use it. It is not enough to just mention it in a branch that is not taken.

n is not defined in the scope that you are trying to use it to fix this define it outside of the while loop and the if statement the while loop is in:
global a
n = 0
Then when you ask the user for what number to start with, that value will replace 0, and you should be good to go. Also instead of declaring global a, why not just make a an input argument for the program() function?

Just to make sure, declare n outside of the loop first:
n = None
while True:
try:
n = int(raw_input("Text..."))
break
except:
print("Please enter a valid number!")
Note: Usually, you would use break to exit a loop. This is because your method requires an extra variable, which uses more memory (not much, but if you keep doing it, it will stack up).

reprompting after invalid input

There was no problem until I tried to make an input go through validity check and if invalid ask again for input
i'm counting on you for ideas thanks in advance :)
a=0
def reinp(a,b):
while True:
if a in [1,2,3,4,5,6]: #checking for valid input
return int(a)
break
a=input(b)
else:
return print("error")
tried, not working either
def reinp(a,b):
for c in [1,2,3,4,5,6]:
if int(c)==int(a):
return int(a)
break
else:
a=input(b)
a=reinp(a,'Test: ')
This one is the first to make a problem
def reinp2(a,b): #trying to check if it's a number and can be turned to float if not ask again
while check(a):
a=input(b)
return float(a)
def check(a):
try:
float(a)
return False
except ValueError:
return True
Right now the problem is after the check it never breaks free from any while loop
i tried in place of while True:if...break,
while correct:
if... correct=False
didn't work
and it just asks again and again even a condition is met...
there is no raw_input in python 3.2 so i can't use that either
reinp2() is there so if there a solution found for reinp() the same could apply for reinp2() as well a and b are just variables ans[n]=reinp2(ans[n],"Input n: ") the same with reinp() just for another type of variable (one that can be float as well)
The code as it is now show no syntax errors
P.S. i'm using Python 3.2

[EDIT: Deleted original answer, since no longer relevant with fixed formatting on question]
The problem with reinp is that a will be a string, and you're checking it against integers.
...so change:
if a in [1,2,3,4,5,6]: #checking for valid input
to:
if a in ['1','2','3','4','5','6']: #checking for valid input
If you still have a problem with reinp2, perhaps you can show some code that demonstrates the issue. It looks fine to me.

P.S. It's complete i just wanted all of you who helped to know it's running without is any glitches i even customized it so it could receive initial data :) if someone need a permutation solver you know where to find it :)
If someone wants the script:
from math import *
ans=['n','k','choice',0,0,0,0,0]
n,k=0,1
a=['''1 For Permutations P (from n) = n
2 For Variations V (k emelments from n-th class) = n!/(n-k)!
3 For Combinations C (k emelments from n-th class) = n!/(k!(n-k)!) = ( n )
4 Use last answer. ( k )
5 Second Memory
6 Clear memory
Your choice is : ''',
'''+ to add
- to substract
* to multiply
/ to divide
You will undertake?: ''',
"The answer is: "]
def perm():
global ans
ans[n]=reinp2(ans[n],"Input n: ")
if ans[5]==0:
ans[3]=factorial(ans[n])
ans[6]=ans[3]
return print(a[2], ans[6])
else:
ans[4]=factorial(ans[n])
ans[6]=ops(ans[3],ans[4],ans[5])
return print(a[2], ans[6])
ans[n]=''
ans[k]=''
def var():
global ans
ans[n]=reinp2(ans[n],"Input n: ")
ans[k]=reinp2(ans[k],"Input k: ")
if ans[5]==0:
ans[3]=factorial(ans[n])/(factorial(ans[n]-ans[k]))
ans[6]=ans[3]
return print(a[2], ans[6])
else:
ans[4]=factorial(ans[n])/(factorial(ans[n]-ans[k]))
ans[6]=ops(ans[3],ans[4],ans[5])
return print(a[2], ans[6])
ans[n]=''
ans[k]=''
def comb():
global ans
ans[n]=reinp2(ans[n],"Input n: ")
ans[k]=reinp2(ans[k],"Input k: ")
if ans[5]==0:
ans[3]=factorial(ans[n])/((factorial(ans[n]-ans[k]))*(factorial(ans[k])))
ans[6]=ans[3]
return print(a[2], ans[6])
else:
ans[4]=factorial(ans[n])/((factorial(ans[n]-ans[k]))*(factorial(ans[k])))
ans[6]=ops(ans[3],ans[4],ans[5])
return print(a[2], ans[6])
ans[n]=''
ans[k]=''
def ent():
global ans,a
ans[2]=reinp(ans[2],a[0])
if ans[2]==5:
if ans[3]!=0:
ans[7]=ans[3]
print(ans[7])
ent()
if ans[2]==6:
clear()
print("Done!")
ent()
if ans[3]==0 and ans[2]==4:
print('The memory is empty...')
ent()
elif ans[3]!=0 and ans[2]==4:
ans[3]=ans[3]
ans[5]=reinp1(ans[5],a[1])
if ans[5] == '+' :
ans[5]='add'
print("Adding")
elif ans[5] == '-' :
ans[5]='sub'
print("Substracting")
elif ans[5] == '*' :
ans[5]='mul'
print("Multiplication")
elif ans[5] == '/' :
ans[5]='div'
print("Dividing")
ans[2]='choice'
ent()
if ans[2]==1:
perm()
elif ans[2]==2:
var()
elif ans[2]==3:
comb()
clear1()
ent()
def ops(a,b,c):
if c=='add':
return a+b
if c=='sub':
return a-b
if c=='mul':
return a*b
if c=='div':
return a/b
def reinp(a,b):
while True:
a=input(b)
if str(a) in ['1','2','3','4','5','6']:
return int(a)
break
else:
print('There was an error please try again:')
def reinp1(a,b):
while True:
a=input(b)
if a in ["+", "-", "*", "/"]:
return a
break
def reinp2(a,b):
while check2(a):
a=input(b)
return float(a)
def check2(a):
try:
float(a)
return False
except ValueError:
return True
def clear():
ans[0]='n'
ans[1]='k'
ans[2]='choice'
ans[3]=0
ans[4]=0
ans[5]=0
ans[7]=ans[6]
ans[6]=0
def clear1():
ans[0]='n'
ans[1]='k'
ans[2]='choice'
ent()