how to count the frequency of letters in text excluding whitespace and numbers?

user_12272304 0
Viewed 28824

Use a dictionary to count the frequency of letters in the input string. Only letters should be counted, not blank spaces, numbers, or punctuation. Upper case should be considered the same as lower case. For example, count_letters("This is a sentence.") should return {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}

def count_letters(text):
      result = {}
      # Go through each letter in the text
      for letter in text:
        # Check if the letter needs to be counted or not
        if letter not in result:
          result[letter.lower()] = 1
        # Add or increment the value in the dictionary
        else:
          result[letter.lower()] += 1
      return result

    print(count_letters("AaBbCc"))
    # Should be {'a': 2, 'b': 2, 'c': 2}

    print(count_letters("Math is fun! 2+2=4"))
    # Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

    print(count_letters("This is a sentence."))
    # Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
python
23 Answers
def count_letters(text):
  result = {}
  text = text.lower()
  # Go through each letter in the text
  for letter in text:
   
    # Check if the letter needs to be counted or not
    if letter.isalpha() :
      # Add or increment the value in the dictionary
      count = text.count(letter)
      result[letter] = count
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_134972620

This should work:

>>> from collections import Counter
>>> from string import ascii_letters
>>> def count_letters(s) :
...     filtered = [c for c in s.lower() if c in ascii_letters]
...     return Counter(filtered)
... 
>>> count_letters('Math is fun! 2+2=4')
Counter({'a': 1, 'f': 1, 'i': 1, 'h': 1, 'm': 1, 'n': 1, 's': 1, 'u': 1, 't': 1})
>>>
user_13292960

So I got your question, 

def count_letters(text):
  result = {}
  text = text.lower()
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if letter in "abcdefghijklmnopqrstuvwxyz":
      #
      if letter not in result:
        result[letter] = 1
      # Add or increment the value in the dictionary
      else:
        result[letter] += 1
  return result

  print(count_letters("AaBbCc"))

  # Should be {'a': 2, 'b': 2, 'c': 2}

  print(count_letters("Math is fun! 2+2=4"))
  # Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 
  1, 'n': 1}

  print(count_letters("This is a sentence."))
  # Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 
  1}
user_134650820 
def count_letters(text):
  result = {}
  for letter in text:
    #check if it alphabet or something else
    # Check if the letter needs to be counted or not
    if letter.isalpha():
      result[letter.lower()]=result.get(letter.lower(),0)+1
    # Add or increment the value in the dictionary
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_136548230 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  text=text.lower()
  for letter in text:
    if letter in 'abcdefghijklmnopqrtsuvwxyz':

      if letter in result:
        result[letter]+=1
      
      else:
        result[letter]=1
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_111542390

The ".isalpha()" method comes in very handy. See how I solved it:

def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    
    if letter.isalpha() and letter not in result:
      letter=letter.lower()
      result[letter]=1
    elif letter.isalpha()==False:
      pass
    else:
      result[letter]+=1

    ___
    # Add or increment the value in the dictionary
    ___
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_105960210

you can use the .isalpha() method to check if the character is an alphabet letter.

Then use the .get method to return the value from a specific key.

def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text.lower():
    # Check if the letter needs to be counted or not
    if(letter.isalpha()):
      result[letter] = result.get(letter,0)+1
    # Add or increment the value in the dictionary
    
  return result
user_152962380

if letter.isalpha() and letter != " ": checks if the letter is only a letter, not a number, a punctuation or a blank space.

def count_letters(text):
  result = {}
  # Go through each letter in the text
  text_lower=text.lower()
  # Go through each letter in the text
  for letter in text_lower:
    # Check if the letter needs to be counted or not
    if letter.isalpha() and letter != " ":
      if letter not in result:
        result[letter] = 0  
    # Add or increment the value in the dictionary
      result[letter] += 1
  return result
user_50286160 
def count_letters(text):
 r = {}
  # Go through each letter in the text
 for letter in text:
    # Check if the letter needs to be counted or not
     for letter in text:
# Check if the letter needs to be counted or not
 for alp in letter:
  # To check the letters are alphabets or not
  if alp in ascii_letters:
   #Converting into lowercase as python is case sensitive
    if alp.lower() in r and alp!=' ':
      r[alp.lower()]+=1
    elif alp.lower() not in r and alp!=' ':
      r[alp.lower()]=1
  # Add or increment the value in the dictionary
  return r

print(count_letters("AaBbCc"))
print(count_letters("Math is fun! 2+2=4"))
print(count_letters("This is a sentence."))
user_134886210 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if (letter.lower() not in result ) :
      if not letter.isalpha():
        continue
      result[letter.lower()] = 0
             # Add or increment the value in the dictionary
    result[letter.lower()] += 1
    continue
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_135485650 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text.lower():
    # Check if the letter needs to be counted or not
    if letter.isalpha() and letter not in result:
    # Add or increment the value in the dictionary
      result[letter] = text.lower().count(letter) 
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_135485650 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if letter.isalpha():
      result[letter.lower()]=result.get(letter.lower(),0)+1
    # Add or increment the value in the dictionary
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_136548230 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if letter.isalpha():
      if letter not in result:
        result[letter.lower()] = 1
      else:
        result[letter.lower()] +=1
    # Add or increment the value in the dictionary
    
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}
user_136687330

Well, in the second comment it says that you should : # Check if the letter needs to be counted or not

You did not check this. You checked only if the letter is in your dictionary named 'result', which is needed to add characters that don't exist already in the new dictionary. In this case, your program takes a blank space as a "letter". If we were to change the 'letter' variable as 'element', things would be more clear.

if letter.isalpha() == True:

You should use the above line to check only for the letters. For each element of the input text, this block would be skipped when the a non-letter character is met(blank space, number of special character).

All in all, your script should look like this:

def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if letter.isalpha() == True:
      if letter.lower() not in result:
        result[letter.lower()] = 1
    # Add or increment the value in the dictionary
      else:
        result[letter.lower()] += 1
    
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_139305150

This is what i did

def count_letters(text):
    result = {}
  # Go through each letter in the text
    text=text.lower()
    for letter in text:
    # Check if the letter needs to be counted or not
        if letter.isalpha():
    # Add or increment the value in the dictionary
            result[letter] = result.get(letter,0) + 1
        else:
            pass
    return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}
print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}
print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_140215790 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if type(letter)==str:
    # Add or increment the value in the dictionary
     if letter not in result:
       result[letter.lower()]=1
     else:
        result[letter.lower()]+=1


    
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_146044850 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text.lower():
    # Check if the letter needs to be counted or not
    if letter.isalpha() and letter not in result:
    # Add or increment the value in the dictionary
      result[letter] = text.count(letter)
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_151945750 
    def count_letters(text):
  result = {}
  # Go through each letter in the text
  text=text.casefold()
  for letter in text:
    # Check if the letter needs to be counted or not
    if (letter.isalpha()): 

    # Add or increment the value in the dictionary
      result.update({letter:text.count(letter)})
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_153768400 
def count_letters(text):
  result = {}
  for letter in text.lower():
    if letter.isalpha():
      lettercount = text.lower().count(letter)
      result[letter] = lettercount
  return result
user_162871500 
def count_letters(text):
    result = {}
    text = text.lower().replace(" ","")
    text = text.replace("", " ").split()
    dummy = []
    dummy1 = ""

    for x in text: # remove non-letter
        if x.isalpha():
            dummy.append(x)
            dummy1 = "".join(dummy)

    for letter in dummy1:
        if letter not in result:
            result[letter] = 0
        result[letter] += 1
    return result

print(count_letters("AaBbCc"))
print(count_letters("Math is fun! 2+2=4"))
print(count_letters("This is a sentence."))
user_139678300 
def  count_letters(text):
    result = {}
    for letter in text.lower():
        if letter == " " or letter.isalpha() == False:
            continue:
        if letter not in result:
            result[letter] = 0
        result[letter] += 1
    return result
user_106258010 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text.lower():
    # Check if the letter needs to be counted or not
     if letter.isalpha() and letter not in result:
       result[letter] = text.lower().count(letter)
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_174046620 
def count_letters(text):
  result = {}
  # Go through each letter in the text
  for letter in text:
    # Check if the letter needs to be counted or not
    if letter .isalpha() and letter not in result:
    # Add or increment the value in the dictionary
      result[letter.lower()]=text.lower().count(letter)
  return result

print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}

print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}

print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
user_118850850
Related