![]() ![]() When specifying a slice you can omit start and end points. Note that strings can be sliced as well as lists and tuples. The above lines of code take a slice from the 4th element in the sequence up to but not including the 7th element. The output of each statement will be included in a comment after it starting with ‘>’. Throughout this post we will be using the variables defined in the below example but to avoid clutter they will only be included in this first example. Thinking this way will make understanding slicing a lot easier. The diagram above shows how to picture sequence indexes and the values they reference. The slice will be between these walls, which of course will not include the value behind the end wall because we only go up to the wall and don’t pass it. Then the start and end points reference these walls, not the values behind them. For the more visual folks another way is to to picture a wall before each value in the sequence. In other words the slice will be from the start point up to but not including the end point. One way to remember this is that the start point is inclusive and the end point is exclusive. For example if you choose the starting point to be 0 and the end point to be 5, the slice will include indexes 0, 1, 2, 3 and 4. However it doesn’t work the way you might first assume it to. Slicing has incredibly simple syntax after a sequence type variable inside square brackets you define a start point, an end point and a step, separated by colons like so var. Slicing has more uses than I can think of or list here, but some of many useful applications include string manipulation and various mathematical uses when using NumPy you will encounter slicing a lot. It gives you to ability to manipulate sequences with simple and concise syntax. Also, with a slice if you do not specify the start or stop index than Python will go all the way to the beginning or end of the string, respectively.Slicing is an incredibly useful and powerful feature of python. If you are getting one too many or too few characters with a slice it is probably because of a misunderstanding in how it is used. This is important to pay attention to the inclusive start index and the exclusive end index. In Python the first number of the slice is the start and the last number is where python stops slicing exclusively. A slice operator is a type of notation that tells the language what index to start at and what index to stop at. To do this we will use what Python calls a slice operator. That is it, regardless if you are trying grab the first character of the string or any of the last characters of a string it is important to verify the index will exist so that an exception is not thrown Last n characters of a stringĪnother one of the different ways available is to grab a set of characters. print( "The last character of testString is: %s " % lastChar) > testString = "" > if len(testString) > 0: In the case of the index at -1 Python will select the last index of the string. One other cool feature of Python is that we can also index in reverse! Just use a negative number starting at -1 to select a character in the string. Why is the last index in the string 22 and not 23? That is because Python starts counting the first index at 0 making the second character at index 1. Given the 23 characters, the letter “h” is located at index position 22. ![]() So in the example of “stand firm in the faith” there are 23 total characters. In Python, you can use the square brackets with a number or a slice notation to tell Python what piece of the string you want to grab. ![]() To understand all the following examples we must first understand how indexing in Python works. There are many ways to get the last character of a string in a Python program. ![]() Below are several techniques showing how to get the last character and last n characters from a string in Python. However, there are many other ways to get the last value of as string in python some may be more useful in your situation than others. >print( "The last character of testString is: %s " % lastChar) >testString = "stand firm in the faith" >lastChar = testString ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |