Replacing instances of a character in a string

Question

This simple code that simply tries to replace semicolons (at i-specified postions) by colons does not work:

for i in range(0,len(line)):
     if (line[i]==\"         


        

Answer 1

You can do the below, to replace any char with a respective char at a given index, if you wish not to use .replace()

word = 'python'
index = 4
char = 'i'

word = word[:index] + char + word[index + 1:]
print word

o/p: pythin

Answer 2

This should cover a slightly more general case, but you should be able to customize it for your purpose

def selectiveReplace(myStr):
    answer = []
    for index,char in enumerate(myStr):
        if char == ';':
            if index%2 == 1: # replace ';' in even indices with ":"
                answer.append(":")
            else:
                answer.append("!") # replace ';' in odd indices with "!"
        else:
            answer.append(char)
    return ''.join(answer)

Hope this helps

Answer 3

to use the .replace() method effectively on string without creating a separate list for example take a look at the list username containing string with some white space, we want to replace the white space with an underscore in each of the username string.

usernames = ["Joey Tribbiani", "Monica Geller", "Chandler Bing", "Phoebe Buffay"]

to replace the white spaces in each username consider using the range function in python.

for i in range(len(usernames)):
    usernames[i] = usernames[i].lower().replace(" ", "_")

print(usernames)

Answer 4

names = ["Joey Tribbiani", "Monica Geller", "Chandler Bing", "Phoebe Buffay"]

usernames = []

for i in names:
    if " " in i:
        i = i.replace(" ", "_")
    print(i)

Output: Joey_Tribbiani Monica_Geller Chandler_Bing Phoebe_Buffay

Answer 5

I wrote this method to replace characters or replace strings at a specific instance. instances start at 0 (this can easily be changed to 1 if you change the optional inst argument to 1, and test_instance variable to 1.

def replace_instance(some_word, str_to_replace, new_str='', inst=0):
    return_word = ''
    char_index, test_instance = 0, 0
    while char_index < len(some_word):
        test_str = some_word[char_index: char_index + len(str_to_replace)]
        if test_str == str_to_replace:
            if test_instance == inst:
                return_word = some_word[:char_index] + new_str + some_word[char_index + len(str_to_replace):]
                break
            else:
                test_instance += 1
        char_index += 1
    return return_word

Answer 6

Turn the string into a list; then you can change the characters individually. Then you can put it back together with .join:

s = 'a;b;c;d'
slist = list(s)
for i, c in enumerate(slist):
    if slist[i] == ';' and 0 <= i <= 3: # only replaces semicolons in the first part of the text
        slist[i] = ':'
s = ''.join(slist)
print s # prints a:b:c;d