在python中替换字符串中的每个字符

Question

I'm working on a script where I'm trying to create a list of strings that, at each subsequent character, have a sub for an input character.

my_replacement = input("Replacement character?: ")
orig_strng = ABCDEFGHIJKL
lst =[]
for i in range(len(orig_strng)):
    a = function to replace orig_strng[i] with my_replacements
    lst.append(a)

If my input is X, the appended lst output from each iteration would look like: XBCDEFGHIJKL, AXCDEFGHIJKL, ABXDEFGHIJKL, etc.

I get that strings themselves are immutable - so i can't directly edit them. How would I be able to tackle this in a python-ic way?

Answer 1

def replace_each(s,letter):
    for i,original_letter in enumerate(s):
        yield "{0}{1}{2}".format(s[:i],letter,s[i+1:])

print(list(replace_each("ABCDEFGHI","x")))

is pretty pythonic I think

Answer 2

You can convert the string into a list, perform the replacement, then convert it back into a string with join

def foo(my_string, i, replacement):
    my_list = list(my_string)
    my_list[i] = replacement
    return "".join(my_list)

foo(orig_strng, 1, "X")
#'AXCDEFGHIJKL'

Answer 3

The string method replace() works nicely here for the example case but not necessarily for all cases.

my_replacement = input("Replacement character?: ")
orig_strng = ABCDEFGHIJKL
lst =[]
for i in range(len(orig_strng)):
    a = orig_strng.replace(orig_string[i], my_replacement)
    lst.append(a)

If you wanted to, you could do this with a list comprehension:

a = [orig_string.replace(orig_string[i], my_replacement) for i in orig_string]

Answer 4

Is this what you mean?

def foo(string,i,replacement):
    return string[:i]+replacement+string[i+1:]

Answer 5

I find that translation tables and the translate function often come in handy. Like you said, strings are immutable, so the translate function returns a copy with the translation completed.

The example below allows you to input a replacement string (not just a single character), and it will replace all occurrences of the character(s) to be translated with the provided input character(s).

from string import maketrans

original = 'ABCDEFGHIJK'
n = len(original)
user_in = "XYZ" #can also just be a single character X
m = min(len(user_in), n)
for i in range(n):
    trans_table = maketrans((original[i:] + original[:i])[:m], user_in[:m])
    new = original.translate(trans_table)
    print new

Output

XYZDEFGHIJK
AXYZEFGHIJK
ABXYZFGHIJK
ABCXYZGHIJK
ABCDXYZHIJK
ABCDEXYZIJK