Working with Strings in Python

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It is somewhat difficult to define a string. In some ways, a string is text such as what is found in a book or even in this blog.  Strings are made up of characters such as letters and even symbols such as %#&@**. However, the computer does not use these characters but converts them to numbers for processing.

In this post, we will learn some of the basics of working with strings in Python. This post could go on forever in terms of what you can do with text so we will only address the following concepts

  • Finding individual characters
  • Modifying text

Finding Individual Characters

Finding individual characters in a string is simple. You simply need to type the variable name and after the name use brackets and put the number of the location of the character in the string. Below is an example

example="Educational Research Techniques"

print(example[0])
E

As you can see, we created a variable called “example” the content of “example” is the string “Educational Research Techniques”. To access the first letter we use the “print” function, type the name of the variable and inside brackets put the letter 0 for the first position in the string. This gives us the letter E. Remeber that Python starts from the number 0 and not 1.

If you want to start from the end of the string and go backward you simply use negative numbers instead of positive as in the example below.

example="Educational Research Techniques"
print(example[-1])
s

You can also get a range of characters.

example="Educational Research Techniques"
print(example[0:5])
Educa

The code above is telling python to take from position 0 to 4 but not including 5.

You can do even more creative things such as pick characters from different spots to create new words

example="Educational Research Techniques"
print(example[0:2] + example[20:25])
Ed Tech

Modifying Strings

It is also possible to modify the text in the string such as making all letters upper or lower case as shown below.

example.upper()
'EDUCATIONAL RESEARCH TECHNIQUES'

example.lower()
'educational research techniques'

The upper() function capitalizes and the lower() function make small case.

It is also possible to count the length of a string and swap the case with the len() and swapcase() functions respectively.

len(example)
31

example.swapcase()
'eDUCATIONAL rESEARCH tECHNIQUES'

Python allows you to count how many times a character appears using the count() function. You can also use the replace() to find characters and change them.

example.count('e')
4

example.replace('e','q')
'Educational Rqsqarch Tqchniquqs'

As you can see, the lower case letter ‘e’ appears four times. In the second line, python replaces all the lower case ‘e’s with the letter ‘q’.

Conclusion

Of course, there is so much more than we could do with strings. However, this post provides an introduction to what is possible.

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