Pythonにおけるfindメソッドを使った文字列検索の実例14選

text = "Python is an easy to learn, powerful programming language."
word = "powerful"
position = text.find(word)
print(f"The word '{word}' is found at index {position}.")

text = "Python is an easy to learn, powerful programming language."
substring = "java"
position = text.find(substring)
if position == -1:
    print(f"The substring '{substring}' is not found in the text.")
else:
    print(f"The substring '{substring}' is found at index {position}.")

text = "Python is an easy to learn, powerful programming language."
substring = "python"
position = text.lower().find(substring.lower())
if position != -1:
    print(f"The substring '{substring}' is found at index {position} (case-insensitive).")
else:
    print(f"The substring '{substring}' is not found in the text (case-insensitive).")

text = "Python is an easy to learn, powerful programming language. Python is often used for web development, data analysis, artificial intelligence, and more."
substring = "Python"

positions = []
start = 0
while True:
    position = text.find(substring, start)
    if position == -1:
        break
    positions.append(position)
    start = position + 1

if positions:
    print(f"The substring '{substring}' is found at positions: {positions}")
else:
    print(f"The substring '{substring}' is not found in the text.")

with open("sample.txt", "r", encoding="utf-8") as file:
    content = file.read()
    substring = "Python"
    position = content.find(substring)
    if position != -1:
        print(f"The substring '{substring}' is found in the file at index {position}.")
    else:
        print(f"The substring '{substring}' is not found in the file.")

strings = ["apple", "banana", "cherry", "date", "elderberry"]
substring = "er"
for string in strings:
    if string.find(substring) != -1:
        print(f"The substring '{substring}' is found in '{string}'.")
    else:
        print(f"The substring '{substring}' is not found in '{string}'.")

The substring 'er' is not found in 'apple'.
The substring 'er' is not found in 'banana'.
The substring 'er' is found in 'cherry'.
The substring 'er' is not found in 'date'.
The substring 'er' is found in 'elderberry'.

text = "This is a sample text."
first_space = text.find(" ")
last_space = text.rfind(" ")
print(f"The first space is found at index {first_space}.")
print(f"The last space is found at index {last_space}.")

The first space is found at index 4.
The last space is found at index 15.

text = "Python is an easy to learn, powerful programming language."
substrings = ["easy", "powerful", "programming"]
for substring in substrings:
    position = text.find(substring)
    if position != -1:
        print(f"The substring '{substring}' is found at index {position}.")
    else:
        print(f"The substring '{substring}' is not found in the text.")

The substring 'easy' is found at index 12.
The substring 'powerful' is found at index 26.
The substring 'programming' is found at index 36.

import re

text = "The price is $10.50."
pattern = r"\$\d+\.\d+"
match = re.search(pattern, text)
if match:
    start = match.start()
    end = match.end()
    print(f"The price is found at index {start} to {end - 1}.")
else:
    print("No price found in the text.")

def search_substring(text, substring):
    try:
        if substring in text:
            position = text.find(substring)
            print(f"The substring '{substring}' is found at index {position}.")
        else:
            print(f"The substring '{substring}' is not found in the text.")
    except TypeError:
        print("Invalid input. Please provide strings for both text and substring.")

# 使用例
search_substring("Hello, world!", "world")
search_substring("Hello, world!", "python")
search_substring(42, "hello")

The substring 'world' is found at index 7.
The substring 'python' is not found in the text.
Invalid input. Please provide strings for both text and substring.

text = "Hello, world!"
substring = "world"
start = 0
end = len(text)
position = text.find(substring, start, end)  # 正しい引数の数

number = 42
position = str(number).find("4")  # 整数を文字列に変換

text = "Hello, world!"
substring = "python"
try:
    position = text.find(substring)
    print(f"The substring '{substring}' is found at index {position}.")
except ValueError:
    print(f"The substring '{substring}' is not found in the text.")

import requests

url = "https://example.com"
response = requests.get(url)
html_content = response.text

keyword = "Python"
if keyword in html_content:
    position = html_content.find(keyword)
    surrounding_text = html_content[position - 20:position + 20]
    print(f"The keyword '{keyword}' is found in the HTML content.")
    print(f"Surrounding text: ...{surrounding_text}...")
else:
    print(f"The keyword '{keyword}' is not found in the HTML content.")

The keyword 'Python' is found in the HTML content.
Surrounding text: ...earning <strong>Python</strong> programming...

import pandas as pd

data = [
    {"id": 1, "text": "Python is a versatile language."},
    {"id": 2, "text": "It is easy to learn Python."},
    {"id": 3, "text": "Python has a large community."},
    {"id": 4, "text": "I enjoy coding in Python."}
]

df = pd.DataFrame(data)

keyword = "Python"
df["contains_keyword"] = df["text"].apply(lambda x: keyword in x)
df["keyword_position"] = df["text"].apply(lambda x: x.find(keyword))

print(df)

   id                              text  contains_keyword  keyword_position
0   1    Python is a versatile language.              True                 0
1   2       It is easy to learn Python.              True                18
2   3    Python has a large community.              True                 0
3   4         I enjoy coding in Python.              True                16

log_file = "application.log"
error_keyword = "ERROR"

with open(log_file, "r") as file:
    for line in file:
        if error_keyword in line:
            error_position = line.find(error_keyword)
            error_message = line[error_position:].strip()
            print(f"Error found: {error_message}")

Error found: ERROR: Division by zero
Error found: ERROR: File not found

import nltk
from nltk.sentiment import SentimentIntensityAnalyzer

text = "Python is a great programming language. It is easy to learn and has a wide range of applications. However, sometimes it can be slow compared to compiled languages."

sentences = nltk.sent_tokenize(text)
sia = SentimentIntensityAnalyzer()

for sentence in sentences:
    if "Python" in sentence:
        sentiment_scores = sia.polarity_scores(sentence)
        print(f"Sentence: {sentence}")
        print(f"Sentiment scores: {sentiment_scores}")
        print()

Sentence: Python is a great programming language.
Sentiment scores: {'neg': 0.0, 'neu': 0.508, 'pos': 0.492, 'compound': 0.6249}

Sentence: However, sometimes it can be slow compared to compiled languages.
Sentiment scores: {'neg': 0.13, 'neu': 0.87, 'pos': 0.0, 'compound': -0.2263}