Letters in decreasing order of frequency #21410

MaziarAm · 2019-01-04T13:51:24Z

MaziarAm
Jan 4, 2019

Hey everone, so I had this exercise :

“Write a program that reads a file and prints the letters
in decreasing order of frequency. Your program should convert all the
input to lower case and only count the letters a-z. Your program should
not count spaces, digits, punctuation, or anything other than the letters
a-z.”

And I managed to solve it, and here’s a part of my code :

fname = input("Enter a file name: ")
if len(fname) < 1 : fname = "romeo.txt"
try :
    fhand = open(fname)
except :
    print("Enter a proper file name",fname )
    quit()
#read the file into a big string

words = fhand.read()
#lower the string

words = words.lower()
letters = list()

for i in words :

if i.isalpha() == True :

letters.append(i)

And it works just fine. However, I was looking up for other solutions online and I found one in the answer section of the book(Python for everybody), it’s pretty much like mine but it has an extra line :

words = fhand.read()
#lower the string, don't worry about digits, punctuation etc.

words = words.lower()
#change the string into single letters

twords = tuple(words)
letters = list()

for i in twords :

#we only choose the alphabet letters

if i.isalpha() == True :

letters.append(i)

I was wondering why the following line is added ? Because the code just works fine without it

twords = tuple(words)

Answered by Wabri

Jan 4, 2019

I dont think there is a real reason. I think the only one reason that i have in mind is maybe to split the tasks of words and twords. The output of letters with twords and words are the same (I didnt tried it but I’m sure of that). To test the output of words and twords you can do something like this:

fname = input("Enter a file name: ")
if len(fname) < 1 : fname = "romeo.txt"
try :
    fhand = open(fname)
except :
    print("Enter a proper file name",fname )
    quit()
#read the file into a big string

words = fhand.read()
#lower the string

words = words.lower()
letters = list()

for i in words :

if i.isalpha() == True :

letters.append(i)
twords = tuple(words)
letters2 = list()

for i in tw…

View full answer

fire-eggs · 2019-01-04T17:33:20Z

fire-eggs
Jan 4, 2019

Without being able to absolutely confirm this, I believe this is a historical oddity. The behavior of strings changed between Python 2 and Python 3; the tuple() line is likely necessary for Python 2 support with Unicode?

0 replies

Wabri · 2019-01-04T17:45:51Z

Wabri
Jan 4, 2019

I dont think there is a real reason. I think the only one reason that i have in mind is maybe to split the tasks of words and twords. The output of letters with twords and words are the same (I didnt tried it but I’m sure of that). To test the output of words and twords you can do something like this:

fname = input("Enter a file name: ")
if len(fname) < 1 : fname = "romeo.txt"
try :
    fhand = open(fname)
except :
    print("Enter a proper file name",fname )
    quit()
#read the file into a big string

words = fhand.read()
#lower the string

words = words.lower()
letters = list()

for i in words :

if i.isalpha() == True :

letters.append(i)
twords = tuple(words)
letters2 = list()

for i in twords :

if i.isalpha() == True :

letters2.append(i)
print(letters==letters2)

and if the output is True than the output are the same (I’m sure it will).

Hope to solve your doubts

-Gabriele-

0 replies

MaziarAm · 2019-01-06T12:46:19Z

MaziarAm
Jan 6, 2019
Author

Thanks!

I’m not sure but maybe it’s what you’re saying because in some of the book slides,there are references to Python 2.

0 replies

MaziarAm · 2019-01-06T12:47:28Z

MaziarAm
Jan 6, 2019
Author

Yeah I think it’s used maybe to explain a little more about what’s going on. And yes the output is exactly the same

Thanks !

0 replies

Wabri · 2019-01-06T15:21:08Z

Wabri
Jan 6, 2019

Dont forget to set it as solution 🙂

0 replies

pythonlearner18 · 2020-04-17T00:41:49Z

pythonlearner18
Apr 17, 2020

Where did you count the frequency of alphabets?

0 replies

vmatom · 2022-04-29T19:29:05Z

vmatom
Apr 29, 2022

Well here is no count. But it’s easy to add.

counts = dict() #create empty dictionary
disallowed_characters="!,.?:;'—...\n1234567890()-/+><#@$%^&*~№| " #add line of punctuation marks that we need to expel
try:
    op = open(input("Enter a file name:")).read().lower()
except FileNotFoundError:
    print('File cannot be opened:', fname)
    quit()
for character in disallowed_characters:
    op= op.replace(character,'')
#print(op)
#type(op)
letters=list()
#print(letters)
for i in op:
    counts[i]=counts.get(i,0)+1
#print(counts)
for k,v in counts.items():
    letters.append((v,k))
letters=sorted(letters,reverse=True)
for v,k in letters:
    print (k,v)

0 replies

ghost · 2023-04-09T06:26:09Z

ghost
Apr 9, 2023

Oh, everything turns out to be so simple, but I solved it using the methods of the py4e books + a little help on github, because I could not fully understand the assignment

import string

fileName = input('Enter a file name: ')
file = open(fileName)

count = 0
d = dict()
lst = list()

for line in file:
    line = line.translate(line.maketrans('', '', string.digits))
    line = line.translate(line.maketrans('', '', string.punctuation))
    line = line.lower()

    words = line.split()
    for word in words:
        for letter in word:
            count += 1
            d[letter] = d.get(letter, 0) + 1

for k, v in list(d.items()):
    lst.append((v / count, k))

lst.sort(reverse=True)

for k, v in lst:
    print(f'{v} {k:.3f}')

0 replies

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Letters in decreasing order of frequency #21410

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Letters in decreasing order of frequency #21410

Replies: 8 comments

MaziarAm Jan 6, 2019 Author

MaziarAm Jan 6, 2019 Author

MaziarAm
Jan 6, 2019
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MaziarAm
Jan 6, 2019
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