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how we can use variables, which are described inside the loop, out side the loop in python

Below is my code. Here, I am trying to read the variable gobs(x) from an input file and then I want to use it for other calculations, eg., computing error(x). But, I found, I can read it from input file properly within the loop, but when trying to use it outside the loop, only the first data is getting transferred. For all 100 data, which I read as gobs(x) inside the loop, it is showing the value of last data only, when I am using it outside the loop.
code started below
constant = 99
x0=50
z0=5
def gsyn (x):
return (constant*z0)/(z0**2+(x-x0)**2)
with open ('Grav_H_Cyln_v3_output.txt') as finp:
lines=finp.readlines()
for line in lines:
g=float(line)
x=line
def gobs (x):
return g
print (gobs(x)) # here, gobs(x) is printing properly
def error(x):
return (gsyn(x)-gobs(x))
for i in range (1, 100, 1):
x=i
print (error(x)) # here, only the first value of gobs(x) is coming
print ('stop')

This seems like a very odd solution to what is fundamentally a very simple problem. Make gobs a dictionary so you can set or retrieve gobs[x] at will.
gobs = dict()
with open ('Grav_H_Cyln_v3_output.txt') as finp:
lines=finp.readlines()
for line in lines:
g=float(line)
gobs[line] = g
print (gobs[line])

You could try creating a vector gobs[] outside the loop, and filling it up within the loop over lines.
That should do.

Instead of reassigning the value of x on each iteration of your loop, append i to a list that is declared outside of the if-block scope.
x = []
for i in range (1, 100, 1):
x.append(i)
print(x)

Assign variable if list index out of range python error

How to pass a string to a variable if an index error is found? Consider the code:
for l1, l2 in zip(open('file1.list'), open ('file2.list')):
a=fasta1[int(l1)]
b=fasta2[int(l2)]
alignments = pairwise2.align.globalxx(a,b)
top_aln = alignments[0]
aln_a, aln_b, score, begin, end = top_aln
print aln_a+'\n'+aln_b
outfast1 = aln_a
outfast2 = aln_b
A number of these functions must be imported (pairwise2 align),
but the file.lists are single column text files with one sequence id (text and numbers) per line, that are used to extract from the fasta1 and fasta2 text files.
Basically, I want to try: each list command ( a=fasta1[int(l1)]) and if there is no error (the id is in range), do as normal (assign variables a and b for that iteration), but if NOT, assign the 'a' variable some placeholder text like 'GGG':
for l1, l2 in zip(open('file1.list'), open ('file2.list')):
try:
a=fasta1[int(l1)]
except IndexError,e:
a="GGG"
continue
try:
b=fasta2[int(l2)]
except (IndexError):
b="CCC"
continue
This code doesn't quite work (when integrated with above code), which isn't surprising given my lack of python prowess, but I don't quite know why. I actually get no text output, despite the print calls... Am I thinking about this right? If there is NO error in the index, I just want it to go on and do the pairwise alignment (with the first a and b variables) and then print some text to stdout.
Any ideas?

Python's conditional (aka ternary) expressions can one-line this for you. They're often criticized for lack of readability, but I think this example reads well enough.
a = fasta1[int(l1)] if int(l1) < len(fasta1) else "GGG"

You don't need continue, because it will skip that iteration of the loop. Consider the following:
for l1, l2 in zip(open('file1.list'), open ('file2.list')):
a = 'GGG'
b = 'CCC'
try:
a = fasta1[int(l1)]
b = fasta2[int(l2)]
except IndexError:
pass

Python issue with replace statement?

I've been write this practice program for while now, the whole purpose of the code is to get user input and generate passwords, everything almost works, but the replace statements are driving me nuts. Maybe one of you smart programmers can help me, because I'm kinda new to this whole field of programming. The issue is that replace statement only seems to work with the first char in Strng, but not the others one. The other funcs blower the last run first and then the middle one runs.
def Manip(Strng):
#Strng = 'jayjay'
print (Strng.replace('j','h',1))
#Displays: 'hayjay'
print (Strng.replace('j','h',4))
#Displays: 'hayhay'
return
def Add_nums(Strng):
Size=len(str(Strng))
Total_per = str(Strng).count('%')
# Get The % Spots Position, So they only get replaced with numbers during permutation
currnt_Pos = 0
per = [] # % position per for percent
rGen = ''
for i in str(Strng):
if i == str('%'):
per.append(currnt_Pos)
currnt_Pos+=1
for num,pos in zip(str(self.ints),per):
rGen = Strng.replace(str(Strng[pos]),str(num),4);
return rGen
for pos in AlphaB: # DataBase Of The Positions Of Alphabets
for letter in self.alphas: #letters in The User Inputs
GenPass=(self.forms.replace(self.forms[pos],letter,int(pos)))
# Not Fully Formatted yet; you got something like Cat%%%, so you can use another function to change % to nums
# And use the permutations function to generate other passwrds and then
# continue to the rest of this for loop which will generate something like cat222 or cat333
Add_nums(GenPass) # The Function That will add numbers to the Cat%%%
print (rGen);exit()

Transposition Cipher in Python

Im currently trying to code a transposition cipher in python. however i have reached a point where im stuck.
my code:
key = "german"
length = len(key)
plaintext = "if your happy and you know it clap your hands, clap your hands"
Formatted = "".join(plaintext.split()).replace(",","")
split = split_text(formatted,length)
def split_text(formatted,length):
return [formatted[i:i + length] for i in range(0, len(formatted), length)]
def encrypt():
i use that to count the length of the string, i then use the length to determine how many columns to create within the program. So it would create this:
GERMAN
IFYOUR
HAPPYA
NDYOUK
NOWITC
LAPYOU
RHANDS
CLAPYO
URHAND
S
this is know where im stuck. as i want to get the program to create a string by combining the columns together. so it would combine each column to create:
IHNNLRCUSFADOAHLRYPYWPAAH .....
i know i would need a loop of some sort but unsure how i would tell the program to create such a string.
thanks

you can use slices of the string to get each letter of the string in steps of 6 (length)
print(formatted[0::length])
#output:
ihnnlrcus
Then just loop through all the possible start indices in range(length) and link them all together:
def encrypt(formatted,length):
return "".join([formatted[i::length] for i in range(length)])
note that this doesn't actually use split_text, it would take formatted directly:
print(encrypt(formatted,length))
the problem with using the split_text you then cannot make use of tools like zip since they stop when the first iterator stops (so because the last group only has one character in it you only get the one group from zip(*split))
for i in zip("stuff that is important","a"):
print(i)
#output:
("s","a")
#nothing else, since one of the iterators finished.
In order to use something like that you would have to redefine the way zip works by allowing some of the iterators to finish and continue until all of them are done:
def myzip(*iterators):
iterators = tuple(iter(it) for it in iterators)
while True: #broken when none of iterators still have items in them
group = []
for it in iterators:
try:
group.append(next(it))
except StopIteration:
pass
if group:
yield group
else:
return #none of the iterators still had items in them
then you can use this to process the split up data like this:
encrypted_data = ''.join(''.join(x) for x in myzip(*split))

Really weird python error

...
def splitMunipulation(p,threshold=5000):
runs=[];i=0
while i<len(p):
l=[];i+=1
print i,p[i]
while p[i]!=press(0,1,0):
l.append(p[i]);i+=1
else:
runs.append(l)#here i points to another (0,1,0)
return runs
...
record=splitMunipulation(record)
'''
Output:
1 <__main__.press instance at 0x046690A8>
File "H:\mutate.py", line 28, in splitMunipulation
while p[i]!=press(0,1,0):
IndexError: list index out of range
pressis a class
and since print p[i] works well,why p[i] is considered out of range?
Really don't get what's going on
'''

so, a few things..
Firstly, your code is very... unpythonic. This isn't C, so you don't need to use while loops for iteration, and don't use semicolons to separate multiple commands on one line in Python. Ever. Also, the while...else format is confusing and should be avoided.
If you look at the first few 'lines' of your while loop,
while i<len(p):
l=[];i+=1
You keep i below the length of p, but you immediately increase i's value by one. As such, when i=len(p) - 1, you will make i one larger, len(p). So when you try to access p[i], you are trying to access a value that doesn't exist.
Fixing those issues, you would get:
...
def splitMunipulation(p,threshold=5000):
runs=[]
for i in p:
l=[]
print i
if i != press(0,1,0):
runs.append(i)
return runs
...
record=splitMunipulation(record)

while p[i]!=press(0,1,0):
l.append(p[i]);i+=1
The variable i gets incremented in this loop until p[i]!=press(0,1,0). Since nothing is happening to make p longer, or to test that i is not greater than the length of p, it is easy to see how the index could get out of range.

len returns the length, not the last index. If l=[1,2,3], then len(l) returns 3, but l[3] is out of range.
so you should use
while i<len(p)-1
or better yet:
for i in range(len(p)):