Python program to convert camel case string to snake case

Examples :

  Input:  GeeksForGeeks  Output:  geeks_for_geeks  Input:  ThisIsInCamelCase  Output:  this_is_in_camel_case

Let`s see how we can accomplish this task.

Method # 1: Naive approach

This is a naive implementation for converting camel craft into snake craft. First, we initialize the res variable with an empty list and add the first (lowercase) character to it. Now, every time we come across an uppercase alphabet, we add & # 39; _ & # 39; and the alphabet (lowercase) to & # 39; res & # 39;, otherwise just add the alphabet only.

# Python3 string conversion program
# from camel to snake

def change_case ( str ):

res = [ str [ 0 ]. Lower ()]

for c in str [ 1 :]:

if c in ( ` ABCDEFGHIJKLMNOPQRSTUVWXYZ` ):

res.append ( ` _` )

res.append (c.lower ())

else :

res.append (c)

return `` .join (res)

# Driver code

str = "GeeksForGeeks"

print (change_case ( str ))

Exit :

 geeks_for_geeks

Method # 2: Understanding the List






  # Python3 string conversion program  
  # camel to snake  
  
  def   change_case (  str  ): 

  
    return   ` ` .join ([`  _`   +   i.lower ()   if   i.isupper ()  
   else   i   for   i   in   str  ]). lstrip (  `_`  )  

  
  # Driver code  
  str   =   "GeeksForGeeks"  
  print   (change_case (  str  ))

Exit:

 geeks_for_geek s

Method # 3: Python Reduce ()

The Python Reduce () method applies function to all string alphabets, wherever it finds capital letters, it adds "_" in front of it and replaces capital letters with lowercase ones.






  # Python3 conversion program lines  
  # from camel to snake  
  from   functools   import   reduce  
  
  def   change_case (  str  ): 
  
    return   reduce   (  lambda   x, y: x   +   (  `_`   if   y.isupper ()   else   ``)   +   y,   str  ). lower () 

  
  # Driver code  
  str   =   "GeeksForGeeks"  
  print   (change_case (  str   ))

Exit:

 geeks_for_geeks

Method # 4: Python Regex

# Python3 string conversion program # from camel to snake


  import   re 
   
  def   change_case (  str  ): 
    s1   =   re.sub (  `(.) ([AZ] [az] +)`  , r   `1_2 ` ,   str  )  
   return   re.sub (  `([a-z0-9]) ([AZ])`  , r  ` 1_2`  , s1) .lower () 
  
  # Driver code  
  str   =   "GeeksForGeeks"  
  print   (change_case (  str  ))

Exit:

 geeks_for_geeks

Python program to convert camel case string to snake case

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