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Python challenge to convert a string to camelCase

I have a python challenge that if given a string with '_' or '-' in between each word such as the_big_red_apple or the-big-red-apple to convert it to camel case. Also if the first word is uppercase keep it as uppercase. This is my code. Im not allowed to use the re library in the challenge however but I didn't know how else to do it.
from re import sub
def to_camel_case(text):
if text[0].isupper():
text = sub(r"(_|-)+"," ", text).title().replace(" ", "")
else:
text = sub(r"(_|-)+"," ", text).title().replace(" ", "")
text = text[0].lower() + text[1:]
return print(text)

Word delimiters can be - dash or _ underscore.
Let's simplify, making them all underscores:
text = text.replace('-', '_')
Now we can break out words:
words = text.split('_')
With that in hand it's simple to put them back together:
text = ''.join(map(str.capitalize, words))
or more verbosely, with a generator expression,
assign ''.join(word.capitalize() for word in words).
I leave "finesse the 1st character"
as an exercise to the reader.
If you RTFM you'll find it contains a wealth of knowledge.
https://docs.python.org/3/library/re.html#raw-string-notation
'+'
Causes the resulting RE to match 1 or more repetitions of the preceding RE. ab+ will match ‘a’ followed by any non-zero number of ‘b’s
The effect of + is turn both
db_rows_read and
db__rows_read
into DbRowsRead.
Also,
Raw string notation (r"text") keeps regular expressions sane.
The regex in your question doesn't exactly
need a raw string, as it has no crazy
punctuation like \ backwhacks.
But it's a very good habit to always put
a regex in an r-string, Just In Case.
You never know when code maintenance
will tack on additional elements,
and who wants a subtle regex bug on their hands?

You can try it like this :
def to_camel_case(text):
s = text.replace("-", " ").replace("_", " ")
s = s.split()
if len(text) == 0:
return text
return s[0] + ''.join(i.capitalize() for i in s[1:])
print(to_camel_case('momo_es-es'))
the output of print(to_camel_case('momo_es-es')) is momoEsEs

r"..." refers to Raw String in Python which simply means treating backlash \ as literal instead of escape character.
And (_|-)[+] is a Regular Expression that match the string containing one or more - or _ characters.
(_|-) means matching the string that contains - or _.
+ means matching the above character (- or _) than occur one or more times in the string.
In case you cannot use re library for this solution:
def to_camel_case(text):
# Since delimiters can have 2 possible answers, let's simplify it to one.
# In this case, I replace all `_` characters with `-`, to make sure we have only one delimiter.
text = text.replace("_", "-") # the_big-red_apple => the-big-red-apple
# Next, we should split our text into words in order for us to iterate through and modify it later.
words = text.split("-") # the-big-red-apple => ["the", "big", "red", "apple"]
# Now, for each word (except the first word) we have to turn its first character to uppercase.
for i in range(1, len(words)):
# `i`start from 1, which means the first word IS NOT INCLUDED in this loop.
word = words[i]
# word[1:] means the rest of the characters except the first one
# (e.g. w = "apple" => w[1:] = "pple")
words[i] = word[0].upper() + word[1:].lower()
# you can also use Python built-in method for this:
# words[i] = word.capitalize()
# After this loop, ["the", "big", "red", "apple"] => ["the", "Big", "Red", "Apple"]
# Finally, we put the words back together and return it
# ["the", "Big", "Red", "Apple"] => theBigRedApple
return "".join(words)
print(to_camel_case("the_big-red_apple"))

Try this:
First, replace all the delimiters into a single one, i.e. str.replace('_', '-')
Split the string on the str.split('-') standardized delimiter
Capitalize each string in list, i.e. str.capitilize()
Join the capitalize string with str.join
>>> s = "the_big_red_apple"
>>> s.replace('_', '-').split('-')
['the', 'big', 'red', 'apple']
>>> ''.join(map(str.capitalize, s.replace('_', '-').split('-')))
'TheBigRedApple'
>> ''.join(word.capitalize() for word in s.replace('_', '-').split('-'))
'TheBigRedApple'
If you need to lowercase the first char, then:
>>> camel_mile = lambda x: x[0].lower() + x[1:]
>>> s = 'TheBigRedApple'
>>> camel_mile(s)
'theBigRedApple'
Alternative,
First replace all delimiters to space str.replace('_', ' ')
Titlecase the string str.title()
Remove space from string, i.e. str.replace(' ', '')
>>> s = "the_big_red_apple"
>>> s.replace('_', ' ').title().replace(' ', '')
'TheBigRedApple'
Another alternative,
Iterate through the characters and then keep a pointer/note on previous character, i.e. for prev, curr in zip(s, s[1:])
check if the previous character is one of your delimiter, if so, uppercase the current character, i.e. curr.upper() if prev in ['-', '_'] else curr
skip whitepace characters, i.e. if curr != " "
Then add the first character in lowercase, [s[0].lower()]
>>> chars = [s[0].lower()] + [curr.upper() if prev in ['-', '_'] else curr for prev, curr in zip(s, s[1:]) if curr != " "]
>>> "".join(chars)
'theBigRedApple'
Yet another alternative,
Replace/Normalize all delimiters into a single one, s.replace('-', '_')
Convert it into a list of chars, list(s.replace('-', '_'))
While there is still '_' in the list of chars, keep
find the position of the next '_'
replacing the character after '_' with its uppercase
replacing the '_' with ''
>>> s = 'the_big_red_apple'
>>> s_list = list(s.replace('-', '_'))
>>> while '_' in s_list:
... where_underscore = s_list.index('_')
... s_list[where_underscore+1] = s_list[where_underscore+1].upper()
... s_list[where_underscore] = ""
...
>>> "".join(s_list)
'theBigRedApple'
or
>>> s = 'the_big_red_apple'
>>> s_list = list(s.replace('-', '_'))
>>> while '_' in s_list:
... where_underscore = s_list.index('_')
... s_list[where_underscore:where_underscore+2] = ["", s_list[where_underscore+1].upper()]
...
>>> "".join(s_list)
'theBigRedApple'
Note: Why do we need to convert the string to list of chars? Cos strings are immutable, 'str' object does not support item assignment
BTW, the regex solution can make use of some group catching, e.g.
>>> import re
>>> s = "the_big_red_apple"
>>> upper_regex_group = lambda x: x.group(1).upper()
>>> re.sub("[_|-](\w)", upper_regex_group, s)
'theBigRedApple'
>>> re.sub("[_|-](\w)", lambda x: x.group(1).upper(), s)
'theBigRedApple'

Replace character only when character not in parentheses

I have a string like the following:
test_string = "test:(apple:orange,(orange:apple)):test2"
I want to replace ":" with "/" only if it is not contained within any set of parentheses.
The desired output is "test/(apple:orange,(orange:apple))/test2"
How can this be done in Python?

You can use below code to achive expected ouput
def solve(args):
ans=''
seen = 0
for i in args:
if i == '(':
seen += 1
elif i== ')':
seen -= 1
if i == ':' and seen <= 0:
ans += '/'
else:
ans += i
return ans
test_string = "test:(apple:orange,(orange:apple)):test2"
print(solve(test_string))

With regex module:
>>> import regex
>>> test_string = "test:(apple:orange,(orange:apple)):test2"
>>> regex.sub(r'\((?:[^()]++|(?0))++\)(*SKIP)(*F)|:', '/', test_string)
'test/(apple:orange,(orange:apple))/test2'
\((?:[^()]++|(?0))++\) match pair of parantheses recursively
See Recursive Regular Expressions for explanations
(*SKIP)(*F) to avoid replacing the preceding pattern
See Backtracking Control Verbs for explanations
|: to specify : as alternate match

Find the first opening parentheses
Find the last closing parentheses
Replace every ":" with "/" before the first opening parentheses
Don't do anything to the middle part
Replace every ":" with "/" after the last closing parentheses
Put these 3 substrings together
Code:
test_string = "test:(apple:orange,(orange:apple)):test2"
first_opening = test_string.find('(')
last_closing = test_string.rfind(')')
result_string = test_string[:first_opening].replace(':', '/') + test_string[first_opening : last_closing] + test_string[last_closing:].replace(':', '/')
print(result_string)
Output:
test/(apple:orange,(orange:apple))/test2
Warning: as the comments pointed it out this won't work if there are multiple distinct parentheses :(

Removing And Re-Inserting Spaces

What is the most efficient way to remove spaces from a text, and then after the neccessary function has been performed, re-insert the previously removed spacing?
Take this example below, here is a program for encoding a simple railfence cipher:
from string import ascii_lowercase
string = "Hello World Today"
string = string.replace(" ", "").lower()
print(string[::2] + string[1::2])
This outputs the following:
hlooltdyelwrdoa
This is because it must remove the spacing prior to encoding the text. However, if I now want to re-insert the spacing to make it:
hlool tdyel wrdoa
What is the most efficient way of doing this?

As mentioned by one of the other commenters, you need to record where the spaces came from then add them back in
from string import ascii_lowercase
string = "Hello World Today"
# Get list of spaces
spaces = [i for i,x in enumerate(string) if x == ' ']
string = string.replace(" ", "").lower()
# Set string with ciphered text
ciphered = (string[::2] + string[1::2])
# Reinsert spaces
for space in spaces:
ciphered = ciphered[:space] + ' ' + ciphered[space:]
print(ciphered)

You could use str.split to help you out. When you split on spaces, the lengths of the remaining segments will tell you where to split the processed string:
broken = string.split(' ')
sizes = list(map(len, broken))
You'll need the cumulative sum of the sizes:
from itertools import accumulate, chain
cs = accumulate(sizes)
Now you can reinstate the spaces:
processed = ''.join(broken).lower()
processed = processed[::2] + processed[1::2]
chunks = [processed[index:size] for index, size in zip(chain([0], cs), sizes)]
result = ' '.join(chunks)
This solution is not especially straightforward or efficient, but it does avoid explicit loops.

Using list and join operation,
random_string = "Hello World Today"
space_position = [pos for pos, char in enumerate(random_string) if char == ' ']
random_string = random_string.replace(" ", "").lower()
random_string = list(random_string[::2] + random_string[1::2])
for index in space_position:
random_string.insert(index, ' ')
random_string = ''.join(random_string)
print(random_string)

I think this might Help
string = "Hello World Today"
nonSpaceyString = string.replace(" ", "").lower()
randomString = nonSpaceyString[::2] + nonSpaceyString[1::2]
spaceSet = [i for i, x in enumerate(string) if x == " "]
for index in spaceSet:
randomString = randomString[:index] + " " + randomString[index:]
print(randomString)

string = "Hello World Today"
# getting index of ' '
index = [i for i in range(len(string)) if string[i]==' ']
# storing the non ' ' characters
data = [i for i in string.lower() if i!=' ']
# applying cipher code as mention in OP STATEMENT
result = data[::2]+data[1::2]
# inserting back the spaces in there position as they had in original string
for i in index:
result.insert(i, ' ')
# creating a string solution
solution = ''.join(result)
print(solution)
# output hlool tdyel wrdoa

You can make a new string with this small yet simple (kind of) code:
Note this doesn't use any libraries, which might make this slower, but less confusing.
def weird_string(string): # get input value
spaceless = ''.join([c for c in string if c != ' ']) # get spaceless version
skipped = spaceless[::2] + spaceless[1::2] # get new unique 'code'
result = list(skipped) # get list of one letter strings
for i in range(len(string)): # loop over strings
if string[i] == ' ': # if a space 'was' here
result.insert(i, ' ') # add the space back
# end for
s = ''.join(result) # join the results back
return s # return the result

keep quoted blocks intact when splitting by delimiter

Given an example string s = 'Hi, my name is Humpty-Dumpty, from "Alice, Through the Looking Glass"' and I want to spearate it to the following chunks:
# To Do: something like {l = s.split(',')}
l = ['Hi', 'my name is Humpty-Dumpty', '"Alice, Through the Looking Glass"']
I don't know where and how many delimiters I'll find.
This is my initial idea, and it is quite long, and not exact, as it removes the all delimiters, while I want the delimiters inside quotes to survive:
s = 'Hi, my name is Humpty-Dumpty, from "Alice, Through the Looking Glass"'
ss = []
inner_string = ""
delimiter = ','
for item in s.split(delimiter):
if not inner_string:
if '\"' not in item: # regullar string. not intersting
ss.append(item)
else:
inner_string += item # start inner string
elif inner_string:
inner_string += item
if '\"' in item: # end inner string
ss.append(inner_string)
inner_string = ""
else: # middle of inner string
pass
print(ss)
# prints ['Hi', ' my name is Humpty-Dumpty', ' from "Alice Through the Looking Glass"'] which is OK-ish

You can split by regular expressions with re.split:
>>> import re
>>> [x for x in re.split(r'([^",]*(?:"[^"]*"[^",]*)*)', s) if x not in (',','')]
when s is equal to:
'Hi, my name is Humpty-Dumpty, from "Alice, Through the Looking Glass"'
it outputs:
['Hi', ' my name is Humpty-Dumpty', ' from "Alice, Through the Looking Glass"']
Regular expression explained:
(
[^",]* zero or more chars other than " or ,
(?: non-capturing group
"[^"]*" quoted block
[^",]* followed by zero or more chars other than " or ,
)* zero or more times
)

I solved this problem by avoiding split entirely:
s = 'Hi, my name is Humpty-Dumpty, from "Alice, Through the Looking Glass"'
l = []
substr = ""
quotes_open = False
for c in s:
if c == ',' and not quotes_open: # check for comma only if no quotes open
l.append(substr)
substr = ""
elif c == '\"':
quotes_open = not quotes_open
else:
substr += c
l.append(substr)
print(l)
Output:
['Hi', ' my name is Humpty-Dumpty', ' from Alice, Through the Looking Glass']
A more generalised function could look something like:
def custom_split(input_str, delimiter=' ', avoid_between_char='\"'):
l = []
substr = ""
between_avoid_chars = False
for c in s:
if c == delimiter and not between_avoid_chars:
l.append(substr)
substr = ""
elif c == avoid_between_char:
between_avoid_chars = not between_avoid_chars
else:
substr += c
l.append(substr)
return l

this would work for this specific case and can provide a starting point.
import re
s = 'Hi, my name is Humpty-Dumpty, from "Alice, Through the Looking Glass"'
cut = re.search('(".*")', s)
r = re.sub('(".*")', '$VAR$', s).split(',')
res = []
for i in r:
res.append(re.sub('\$VAR\$', cut.group(1), i))
Output
print(res)
['Hi', ' my name is Humpty-Dumpty', ' from "Alice, Through the Looking Glass"']

How to remove NUL characters from a string in Python? [duplicate]

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]==";" and i in rightindexarray):
line[i]=":"
It gives the error
line[i]=":"
TypeError: 'str' object does not support item assignment
How can I work around this to replace the semicolons by colons? Using replace does not work as that function takes no index- there might be some semicolons I do not want to replace.
Example
In the string I might have any number of semicolons, eg "Hei der! ; Hello there ;!;"
I know which ones I want to replace (I have their index in the string). Using replace does not work as I'm not able to use an index with it.

Strings in python are immutable, so you cannot treat them as a list and assign to indices.
Use .replace() instead:
line = line.replace(';', ':')
If you need to replace only certain semicolons, you'll need to be more specific. You could use slicing to isolate the section of the string to replace in:
line = line[:10].replace(';', ':') + line[10:]
That'll replace all semi-colons in the first 10 characters of the string.

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

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

If you want to replace a single semicolon:
for i in range(0,len(line)):
if (line[i]==";"):
line = line[:i] + ":" + line[i+1:]
Havent tested it though.

You cannot simply assign value to a character in the string.
Use this method to replace value of a particular character:
name = "India"
result=name .replace("d",'*')
Output: In*ia
Also, if you want to replace say * for all the occurrences of the first character except the first character,
eg. string = babble output = ba**le
Code:
name = "babble"
front= name [0:1]
fromSecondCharacter = name [1:]
back=fromSecondCharacter.replace(front,'*')
return front+back

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)

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.
names = ["Joey Tribbiani", "Monica Geller", "Chandler Bing", "Phoebe Buffay"]
usernames = []
to replace the white spaces in each username consider using the range function in python.
for name in names:
usernames.append(name.lower().replace(' ', '_'))
print(usernames)
Or if you want to use one list:
for user in range(len(names)):
names[user] = names[user].lower().replace(' ', '_')
print(names)

How about this:
sentence = 'After 1500 years of that thinking surpressed'
sentence = sentence.lower()
def removeLetter(text,char):
result = ''
for c in text:
if c != char:
result += c
return text.replace(char,'*')
text = removeLetter(sentence,'a')

If you are replacing by an index value specified in variable 'n', then try the below:
def missing_char(str, n):
str=str.replace(str[n],":")
return str

To replace a character at a specific index, the function is as follows:
def replace_char(s , n , c):
n-=1
s = s[0:n] + s[n:n+1].replace(s[n] , c) + s[n+1:]
return s
where s is a string, n is index and c is a character.

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

You can do this:
string = "this; is a; sample; ; python code;!;" #your desire string
result = ""
for i in range(len(string)):
s = string[i]
if (s == ";" and i in [4, 18, 20]): #insert your desire list
s = ":"
result = result + s
print(result)

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

My problem was that I had a list of numbers, and I only want to replace a part of that number, soy I do this:
original_list = ['08113', '09106', '19066', '17056', '17063', '17053']
# With this part I achieve my goal
cves_mod = []
for i in range(0,len(res_list)):
cves_mod.append(res_list[i].replace(res_list[i][2:], '999'))
cves_mod
# Result
cves_mod
['08999', '09999', '19999', '17999', '17999', '17999']

Even more simpler:
input = "a:b:c:d"
output =''
for c in input:
if c==':':
output +='/'
else:
output+=c
print(output)
output: a/b/c/d

i tried using this instead as a 2 in 1
usernames = ["Joey Tribbiani", "Monica Geller", "Chandler Bing", "Phoebe Buffay"]
# write your for loop here
for user in range(0,len(usernames)):
usernames[user] = usernames[user].lower().replace(' ', '_')
print(usernames)

Cleaner way to replace character at a specific index
def replace_char(str , index , c):
return str[:index]+c+str[index+1:]