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Author: martin-martin

how-to-check-if-a-python-string-contains-a-substring/README.md

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+# How to Check if a Python String Contains a Substring
+
+If you're new to programming or come from a different programming language to Python, you may not know what's the best way to check whether a string contains another string in Python.
+
+In this tutorial you'll focus on the most pythonic approach to tackle this task, using the **membership operator `in`**. Additionally, you'll learn how to **identify the right string methods** for related, but different, use cases.
+
+Finally, you'll also learn how to **find substrings in pandas columns**. This is helpful if you need to search through data from a CSV file.
+
+Head over to Real Python to the full tutorial on [How to Check if a Python String Contains a Substring](https://realpython.com/python-string-contains-substring/).

how-to-check-if-a-python-string-contains-a-substring/check_case.py

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+file_content_title = """Hi There And Welcome.
+This Is A Special Hidden File With A Secret Secret.
+I Don'T Want To Tell You The Secret,
+But I Do Want To Secretly Tell You That I Have One.
+"""
+
+# Strings are case-sensitive
+print("secret" in file_content_title)  # False
+
+# Convert the input string to lowercase to generalize matching
+file_content = file_content_title.lower()
+
+print(file_content)
+
+print("secret" in file_content)  # True

how-to-check-if-a-python-string-contains-a-substring/check_substring.py

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+raw_file_content = """Hi there and welcome.
+This is a special hidden file with a SECRET secret.
+I don't want to tell you The Secret,
+but I do want to secretly tell you that I have one.
+"""
+
+# Use the membership operator for pythonic membership checks
+print("secret" in raw_file_content)
+
+# You can do the inverse with `not in`
+print("secret" not in raw_file_content)
+
+# Using `in` is a readable way to check if a string contains a substring
+if "secret" in raw_file_content:
+   print("Found!")

how-to-check-if-a-python-string-contains-a-substring/companies.csv

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+import pandas as pd
+
+
+# Read the CSV data into a pandas dataframe
+companies = pd.read_csv("companies.csv")
+
+# Check the size of the dataframe
+print(companies.shape)
+
+# Inspect the first 5 rows of the dataframe
+print(companies.head())
+
+# Filter for rows where the company slogan contains the word "secret"
+print(companies[companies.slogan.str.contains("secret")])
+
+# Apply a regex pattern to the string search to narrow the results
+print(companies[companies.slogan.str.contains(r"secret\w+")])

how-to-check-if-a-python-string-contains-a-substring/pandas_search.py

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+import re
+
+
+file_content = """hi there and welcome.
+this is a special hidden file with a secret secret.
+i don't want to tell you the secret,
+but i do want to secretly tell you that i have one.
+"""
+
+# Find words that start with "secret"
+print(re.search(r"secret\w+", file_content))
+
+# Inspect what methods on the Match object can give you
+m = re.search(r"secret\w+", file_content)
+print(m.group())  # "secretly"
+print(m.span())  # (128, 136)
+
+# Find the first word followed by certain punctuation characters
+print(re.search(r"secret[\.,]", file_content))
+
+# Find all words followed by certain punctuation characters
+print(re.findall(r"secret[\.,]", file_content))
+
+# Use a capture group to remove the punctuation character
+print(re.findall(r"(secret)[\.,]", file_content))
+
+# Iterate over all matches as Match objects
+for match in re.finditer(r"(secret)[\.,]", file_content):
+   print(match)

how-to-check-if-a-python-string-contains-a-substring/regex_search.py

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+file_content = """hi there and welcome.
+this is a special hidden file with a secret secret.
+i don't want to tell you the secret,
+but i do want to secretly tell you that i have one.
+"""
+
+# Use .index() to get the starting index of the first match
+print(file_content.index("secret"))
+
+# Pass a custom start index to .index() to search from a different point
+print(file_content.index("secret", 60))
+
+# Count the number of matches in the text
+print(file_content.count("secret"))
+
+# Use a for loop to inspect all matches
+for word in file_content.split():
+   if "secret" in word:
+       print(word)
+
+# Use a list comprehension and a conditional check for a one-liner
+print([word for word in file_content.split() if "secret" in word])