Answer fans' questions | count the number and frequency of letters in the text

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​1 Preface ​

In recent days, , Xiaobian received a message from a fan , Want to know how to use python Count the number and frequency of English letters in the text . So close up this article article To answer questions for this fan .

chart 1 Fans of the message

​2 Problem solving ​

This problem can be divided into two parts , One is to use python Realize the operation of text file , Two is python Count the string . For your convenience , Xiaobian will talk about the second part first and then the first part .

​2.1 use python Count the number and frequency of English letters in a given string .​

There are many ways to count the number of occurrences of English letters in a string , Xiaobian will introduce you to a relatively simple , Easy to understand .

“ Statistics ”. To count the number of occurrences of a character , stay python Can be used directly in count() function , For example, the characters to be counted are i, String is text_file, See code for its usage .

count = text_file.count(i) # Count the letters in original text Number of occurrences in this

Through this line of code , You can count the number of occurrences of the desired character in the string , Then the frequency of its occurrence can be directly divided by the number of occurrences divided by the total number of characters . The next step is to count multiple English letters .

“ Filter ”. To count multiple letters , You need to keep performing the first step , So we need to use for loop ,i Just traverse... In the target string . Because you only need to count the English letters , So you can also use python Its own judgment function isalpha(). In addition, in order not to repeat the statistics of the characters during traversal , So you need to do a process on the target string , use python Of set() Function can convert a string into a collection （ Automatically filter duplicate characters ）. See the code for details. .

text_file_set = sorted(set(text_file)) # Sort the text and return the set without duplicate characters for i in text_file_set: # Traversal of the resulting text collection     if i.isalpha(): # Determine whether it is an English letter         count = text_file.count(i) # Count the letters in original text Number of occurrences in this         frequency = count/text_count # Calculate the frequency of the letter         print("%s:%d;%.4f" % (i,count,frequency)) # Output what you want （ Keep the frequency to four decimal places ）

​2.2python Realize the operation of text file .​

Go through the above steps , The letter statistics of the given string has been realized , The given way is to input , Of course, it's troublesome to input by yourself , Even paste and copy is troublesome , So we need to use python Built in functions for open() To help open the target text file . Here's a brief introduction to the following open() Function usage .

open(‘file.name’,’mode’,......)

There are many parameters after the quotation marks , I won't go into details here , Just remember the common ones mode Type and function .

w： Open... In write mode

a： Open... In append mode

r： Open in read-only mode

r+： Turn on in read-write mode

w+： Turn on in read-write mode

rb： Open in binary read mode

wb： Open in binary write mode

ab： Open in binary append mode

rb+： Open in binary read-write mode

wb+： Open in binary read-write mode

ab+： Open in binary append mode

Then use this line of code to open the target text file .

text = open('test.txt','r') # Open target text

​ Be careful ： there test.txt Is under the same path as the code , If not , You need to enter the full path name .​

After opening the file , It can't be used directly , Because its type is not str, So you need to add another line of code to text Convert to an operable string type （str）.

text_file = text.read() # Read target text （ Convert to string type ）

And then you can use type Function to see if str type .

print(type(text),type(text_file)) <class '_io.TextIOWrapper'> <class 'str'>

It can be found that the text has been changed from the original txt Type to str type . Then you can put the code together , Then the problem is solved .

​3 Complete code ​

text = open('test.txt','r') # Open target text text_file = text.read() # Read target text （ Convert to string type ） text_count = len(text_file) # Returns the total number of characters in the text text_file_set = sorted(set(text_file)) # Sort the text and return the set without duplicate characters for i in text_file_set: # Traversal of the resulting text collection     if i.isalpha(): # Determine whether it is an English letter         count = text_file.count(i) # Count the letters in original text Number of occurrences in this         frequency = count/text_count # Calculate the frequency of the letter         print("%s:%d;%.4f" % (i,count,frequency)) # Output what you want （ Keep the frequency to four decimal places ）

Let's see some running effects ：

chart 2 original text Contents of this

chart 3 Run... Part of the effect

​4 summary ​

The problem itself is not difficult , The code is also simple , The small is written in such detail for everyone to understand , I hope that no matter what problems you encounter in the future, you can solve them in this way of thinking step by step .

After the above explanation , I wonder if this fan understands ？ If not, please leave a message below . And if you have any problems that you can't solve or don't understand , You can leave a message in the official account , All the editors of official account will try their best to answer your questions .

END

Lord   Ed    |    Wang Wenxing

responsibility   Ed    |    Jianglaihong

​ where2go The team ​

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