Count number characters python

Python – Count Number of Characters in Text File

You can count number of words in a text file, by first reading the text to a variable, and then counting the characters. We shall go through the sequence of steps required to count the characters.

Steps to Count Number of Characters

To count the number of characters in a text file, follow these steps.

1. Open the file in read mode
2. Read the text using read() function.
3. Get the length of the string, that should be the number of characters in the text file.
4. You can refine the count by cleaning the string like removing white space characters and punctuation marks.

Examples

1. Count characters in a given Text File

In this Python Example, we will read a text file and count the number of characters in it. Consider the following text file.

Welcome to www.pythonexamples.org. Here, you will find python programs for all general use cases.

Python Program

#open file in read mode file = open("C:\data.txt", "r") #read the content of file data = file.read() #get the length of the data number_of_characters = len(data) print('Number of characters in text file :', number_of_characters)

Number of characters in text file : 97

2. Count characters in a given Text File excluding spaces

In this Python Example, we will read a text file and count the number of characters in it excluding white space characters. Consider the following text file.

Welcome to www.pythonexamples.org. Here, you will find python programs for all general use cases.

Python Program

#open file in read mode file = open("C:\data.txt", "r") #read the content of file and replace spaces with nothing data = file.read().replace(" ","") #get the length of the data number_of_characters = len(data) print('Number of characters in text file :', number_of_characters)

Number of characters in text file : 84

Summary

In this tutorial of Python Examples, we learned how to count number of characters in text file, with the help of example programs.

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Count characters and strings in Python

This article explains how to count the number of specific characters (letters) or substrings within a string ( str ) in Python.

For details on how to read a text file as a string, calculate the length (the total character count) of a string, or search for a substring within a string, please refer to the following articles:

Count characters and substrings: count()

The count() method allows you to count the number of specific characters or substrings within a string.

s = 'abc_aabbcc_abc' print(s.count('abc')) # 2 print(s.count('a')) # 4 print(s.count('xyz')) # 0 

If the second argument start and the third argument end are specified, the range of the slice [start:end] is targeted.

print(s.count('a', 4, 10)) # 2 print(s[4:10]) # aabbcc print(s[4:10].count('a')) # 2 

Like slicing, a negative value can specify a position from the end. If end is omitted, the range is up to the end.

print(s.count('a', -9)) # 2 print(s[-9:]) # abbcc_abc print(s[-9:].count('a')) # 2 

count() only counts non-overlapping occurrences of the specified substring. Each character is counted only once.

s = 'abc_abc_abc' print(s.count('abc_abc')) # 1 

To count overlapping substrings, use the regular expression described below.

Count the number of words

For example, if you want to count «am» with the count() method, «Sam» is also counted.

s = 'I am Sam' print(s.count('am')) # 2 

To tally specific words, you can use the split() method, dividing the string into a list of words using a specified delimiter, such as spaces or punctuation. You can then use the count() method on the list to count exact word matches.

l = s.split() print(l) # ['I', 'am', 'Sam'] print(l.count('am')) # 1 

For long sentences, the Counter class of the standard Python library collections is useful for counting the frequency of each word. See the following article.

Keep in mind that using split() to divide a string into words is a basic approach. Since actual sentences may contain various symbols, it is safe to use a natural language processing library such as NLTK.

Count with regex: re.findall()

Use re.findall() to count substrings that match a regex pattern.

re.findall() returns a list of all substrings that match the pattern. Use the built-in len() function to get the total count of matched substrings.

import re s = '123-456-789' print(re.findall('9 ', s)) # ['123', '456', '789'] print(len(re.findall('5 ', s))) # 3 

In the example above, 6 is a regex pattern matching any three-digit number.

You can also count overlapping substrings using a lookahead assertion (? =. ) and grouping () .

s = 'abc_abc_abc' print(re.findall('(?=(abc_abc))', s)) # ['abc_abc', 'abc_abc'] print(len(re.findall('(?=(abc_abc))', s))) # 2 s = '12345' print(re.findall('(?=(5 ))', s)) # ['123', '234', '345'] print(len(re.findall('(?=(2 ))', s))) # 3 

For more information on the re module, see the following article.

Case-insensitive counting

s = 'abc_ABC' print(s.count('abc')) # 1 

For case-insensitive counting, you can convert the string to upper or lower case. Use upper() to make a string all uppercase and lower() to make it all lowercase.

print(s.lower()) # abc_abc print(s.lower().count('abc')) # 2 print(s.upper()) # ABC_ABC print(s.upper().count('ABC')) # 2 

With regex, you can set re.IGNORECASE as the flags parameter in functions like re.findall() for case-insensitive counting.

print(re.findall('abc', s, flags=re.IGNORECASE)) # ['abc', 'ABC'] print(re.findall('ABC', s, flags=re.IGNORECASE)) # ['abc', 'ABC'] 

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Python – Count Number of Characters in Text File

You can count number of words in a text file, by first reading the text to a variable, and then counting the characters. We shall go through the sequence of steps required to count the characters.

Steps to Count Number of Characters

To count the number of characters in a text file, follow these steps.

1. Open the file in read mode
2. Read the text using read() function.
3. Get the length of the string, that should be the number of characters in the text file.
4. You can refine the count by cleaning the string like removing white space characters and punctuation marks.

Examples

1. Count characters in a given Text File

In this Python Example, we will read a text file and count the number of characters in it. Consider the following text file.

Welcome to www.pythonexamples.org. Here, you will find python programs for all general use cases.

Python Program

#open file in read mode file = open("C:\data.txt", "r") #read the content of file data = file.read() #get the length of the data number_of_characters = len(data) print('Number of characters in text file :', number_of_characters)

Number of characters in text file : 97

2. Count characters in a given Text File excluding spaces

In this Python Example, we will read a text file and count the number of characters in it excluding white space characters. Consider the following text file.

Welcome to www.pythonexamples.org. Here, you will find python programs for all general use cases.

Python Program

#open file in read mode file = open("C:\data.txt", "r") #read the content of file and replace spaces with nothing data = file.read().replace(" ","") #get the length of the data number_of_characters = len(data) print('Number of characters in text file :', number_of_characters)

Number of characters in text file : 84

Summary

In this tutorial of Python Examples, we learned how to count number of characters in text file, with the help of example programs.

Источник

Count number of characters in a string in python

In this post, we will see how to count number of characters in a String in Python.

We can think of strings as a collection of characters, with every character at a given index.

Ways to count the number of characters in a string in Python

In this tutorial, we will find out the total number of characters in a string in Python.

Using the len() function

This function is the most straightforward method. The len() function returns the length of a given iterable in Python. We can use it to find the number of characters in a string.

Further reading:

How to compare String in Python

Loop through String in Python

Using the for loop

We can use the for loop to iterate over a string in Python. We can use a counter variable and increment it in every iteration. This variable will return the total number of characters in a string.

• The t variable is given a value of 0.
• We iterate over the string s using the for loop.
• In every iteration, we increment t and display its value after the loop ends.

Using the collections.Counter class

The collections.Counter class stores the elements of a string as key-value pairs. The keys are the characters of the string, and the value of each key is how many times this character occurs in the string.

We can sum up these values to find the total number of characters in the given string.

• We create an object of the Counter class ob .
• We create an object of all the values of the dictionary-like object ob with the values() function.
• The sum() function returns the sum of these values.

Conclusion

In this tutorial, we discussed how to get the characters in a given string in Python. The len() function is the simplest and most used method. We can also use the for loop and Counter class for a lengthy method.

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