An Introduction To Python - Processing Strings
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This document covers an introduction to processing strings in Python, including methods to check character case and count occurrences of characters. It provides examples for counting uppercase letters and vowels, as well as locating positions of matches within a string. The session also notes what was covered in previous classes and highlights topics for the next class, focusing on lists and their algorithms.
![Finding All Matches
• You may need to find the position of each match within a string. For example,
suppose you are asked to print the position of each uppercase letter in a sentence.
• You cannot use the for statement that iterates over all characters because you
need to know the positions of the matches. Instead, iterate over the positions
(using for with range) and look up the character at each position:
sentence = input("Enter a sentence: ")
for i in range(len(sentence)) :
if sentence[i].isupper() :
print(i)](https://image.slidesharecdn.com/13-python-150222080812-conversion-gate01/85/An-Introduction-To-Python-Processing-Strings-5-320.jpg)
An Introduction To Python - Processing Strings
- 1. An Introduction To Software Development Using Python Spring Semester, 2014 Class #13: Processing Strings
- 2. Processing Strings • One of the main usages of loops is to process strings. • Examples: – Count the occurrence of one or more characters in a string – Verify that the contents of a string meet a criteria • All of this requires basic string processing algorithms
- 3. 4 String Processing Methods • variable.isupper – Test to see if current character is upper case – Returns True or False • variable.islower – Test to see if current character is lower case – Returns True or False • variable.upper – Converts current character to upper case • variable.lower – Converts current character to lower case
- 4. Counting Matches • We often want to count the number of values that meet a given condition. • Example: count the number of upper case characters in a string uppercase = 0 for char in string : if char.isupper() : uppercase = uppercase + 1 • Sometimes, you need to count the number of occurrences of multiple characters within a string. • Example, suppose we would like to know how many vowels are contained in a word. vowels = 0 for char in word : if char.lower() in "aeiou" : vowels = vowels + 1 a & b Note: using “.lower” allows us to limit the number of characters that must be specified in the literal string
- 5. Finding All Matches • You may need to find the position of each match within a string. For example, suppose you are asked to print the position of each uppercase letter in a sentence. • You cannot use the for statement that iterates over all characters because you need to know the positions of the matches. Instead, iterate over the positions (using for with range) and look up the character at each position: sentence = input("Enter a sentence: ") for i in range(len(sentence)) : if sentence[i].isupper() : print(i)
- 6. What We Covered Today 1. Tables 1. Creating 2. Accessing 3. Neighbors 4. Summing 2. List Algorithms Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/
- 7. What We’ll Be Covering Next Time 1. Lists, List algorithms Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/
Editor's Notes
- #2: New name for the class I know what this means Technical professionals are who get hired This means much more than just having a narrow vertical knowledge of some subject area. It means that you know how to produce an outcome that I value. I’m willing to pay you to do that.