如何获取 python 中字符串出现的计数？

Question

I created function to detect words I specify and display which line it is in, however, I also want to know how many times in the data do those particular words repeat more than once or their count

def search_multiple_strings_in_file(file_name, list_of_strings):
    """Get line from the file along with line numbers, which contains any string from the list"""
    line_number = 0
    list_of_results = []
    # Open the file in read only mode
    with open("Hello.csv", 'r') as read_obj:
        # Read all lines in the file one by one
        for line in read_obj:
            line_number += 1
            # For each line, check if line contains any string from the list of strings
            for string_to_search in list_of_strings:
                if string_to_search in line:
                    # If any string is found in line, then append that line along with line number in list
                    list_of_results.append((string_to_search, line_number, line.rstrip()))
 
    # Return list of tuples containing matched string, line numbers and lines where string is found
    return list_of_results

# search for given strings in the file 'sample.txt'

matched_lines = search_multiple_strings_in_file('hello.csv', ['pre existing ', 'exclusions','limitations','fourteen','authorize','frequency','automatic','renewal','provision','annual limit','fraud notice'])
 
print('Total Matched lines : ', len(matched_lines))
for elem in matched_lines:
    print('Word = ', elem[0], ' :: Line Number = ', elem[1], ' :: Line = ', elem[2])
  

Is there a way I can upload a sample csv on SO? im new here not sure i have seen how to add attachments. But this app would work with any dummy csv.

I just want my final output to also display the words and their count for example-

Words       Count
exclusions  10
renewal     22

Answer 1

A simple way to include a count in your current code is to use collections.defaultdict() and simple += the count of each matched string.

We can then pass the dict to a Dataframe.from_dict() to generate our output df .

---

import pandas as pd
from collections import defaultdict

def search_multiple_strings_in_file(file_name, list_of_strings):
    """Get line from the file along with line numbers, which contains any string from the list"""
    line_number = 0
    list_of_results = []
    count = defaultdict(lambda: 0)
    # Open the file in read only mode
    with open("Hello.csv", 'r') as read_obj:
        # Read all lines in the file one by one
        for line in read_obj:
            line_number += 1
            # For each line, check if line contains any string from the list of strings
            for string_to_search in list_of_strings:
                if string_to_search in line:
                    count[string_to_search] += line.count(string_to_search)
                    # If any string is found in line, then append that line along with line number in list
                    list_of_results.append((string_to_search, line_number, line.rstrip()))
 
    # Return list of tuples containing matched string, line numbers and lines where string is found
    return list_of_results, dict(count)


matched_lines, count = search_multiple_strings_in_file('hello.csv', ['pre existing ', 'exclusions','limitations','fourteen','authorize','frequency','automatic','renewal','provision','annual limit','fraud notice'])


df = pd.DataFrame.from_dict(count, orient='index').reset_index()
df.columns = ['Word', 'Count']

print(df)

---

Output

             Word  Count
0   pre existing       6
1        fourteen      5
2       authorize      5
3       frequency      5
4       automatic      5
5         renewal      5
6       provision      5
7    annual limit      6
8    fraud notice      6
9      exclusions      5
10    limitations      4

Answer 2

You can do it a number of ways I expect you'll be happy with something like the below. You can use a dictionary in place of a counter easy enough but the Counter is more convenient:

from collections import Counter

def search_multiple_strings_in_file(file_name, list_of_strings):
    """Get line from the file along with line numbers, which contains any string from the list"""
    line_number = 0
    list_of_results = []
    freq_count = Counter()
# Open the file in read only mode
    with open("Hello.csv", 'r') as read_obj:
        # Read all lines in the file one by one
        for line in read_obj:
            line_number += 1
            # For each line, check if line contains any string from the list of strings
            for string_to_search in list_of_strings:
                if string_to_search in line:
                    # If any string is found in line, then append that line along with line number in list
                    list_of_results.append((string_to_search, line_number, line.rstrip()))
                    freq_count[string_to_search] +=line.count(string_to_search)
 
    # Return list of tuples containing matched string, line numbers and lines where string is found
    return (list_of_results, freq_count)

Edit: I realised that I was returning the number of lines that contained the strings instead of the total number of occurrences. I fixed this by adding line.count(string_to_search) instead of just adding 1 per line when a string was contained in the line. It would be a bit more efficient to calculate the count once and test if it's 0 instead of using the if in construct but it is unlikely to be meaningful for your task.

Answer 3

You want your function to return a dictionary here. Iterate word by word to be more efficient.

def search_multiple_strings_in_file(file_name, list_of_strings):
    mapping = {s: [] for s in list_of_strings}

    with open(file_name, 'r') as read_obj:
        for i, line in enumerate(read_obj):
            for word in line.split(' '):
                if word in mapping:
                    mapping[word].append(i)

    return mapping

Demo

with open('fakefile.txt', 'w') as f:
    f.write("Lorem ipsum dolor sit amet\n")
    f.write("consectetur adipiscing elit\n")
    f.write("sed do eiusmod tempor incididunt ut labore et dolore magna aliqua\n")
    f.write("Lorem ipsum dolor sit amet\n")


search_multiple_strings_in_file('fakefile.txt', ['ipsum', 'adipiscing', 'dolor'])
# {'ipsum': [0, 3], 'adipiscing': [1], 'dolor': [0, 3]}