Missing values in string data pose a significant challenge in analysis. Replacing them with the least frequent character can preserve the structure and context while ensuring accuracy. Python libraries offer various techniques to handle this issue and we’ll discuss some of them in this thread.
Note: The output of each method can be different because there can be multiple least frequent characters in a string.
1. Using Pandas library:
In this method, we’ve used several Pandas functions and attributes to accomplish this task:
pd.Series()function was used to convert the target string into an object with each character at a different index.
- The missing characters were then replaced with
value_counts(sort = True)function was used to calculate the frequency count of each character and sort them in descending order.
fillna()function was used to replace empty spaces (
NaNvalues) in the string with the least frequent character, and the result was displayed in string form using
str.cat(sep = '').
2. Using Collections library:
Counterclass in the
collectionsmodule can be used to count the frequency of values in an object.
- In this method, we’ve counted the frequency of characters in the string after replacing empty characters using
replace(' ', '')method.
- The least frequent character is found using
most_common()[-1]which returns a list of tuples of the most common elements and their counts,
[-1]gets the last element i.e., the least frequent one.
- We’ve used
replace()method again to replace empty characters (
' ') with the least frequent character.
3. Using dictionary and "min()" method:
- The string is converted to a list of its characters using the
list()function and a dictionary is created using dictionary comprehension that counts the frequency of each character in the list using
min()function takes the dictionary as an argument and returns the smallest element based on the key function
get()which returns the count of characters from the dictionary. Therefore,
min()returns the key with the minimum count value in the dictionary.
- Finally, all the spaces in the string are replaced with the least frequent character using the
4. Using regular expressions library:
- This method replaces missing values in a string with the least frequent character using functions from the
re.findall()function finds all lowercase letters in the string and removes duplicates by storing them as a set.
- The set is sorted by character count using the key argument in the
- The least frequent character, accessed by
, is then used to replace all missing values in the input string using
re.sub()with the regular expression pattern
\smatching whitespace characters.