Various ways to iterate over sequences The sequence functions illustrated in 4. We can randomize the contents of a list s before iterating over them, using random. We can convert between these sequence types. For example, tuple s converts any kind of sequence into a tuple, and list s converts any kind of sequence into a list.
You can think of regular expressions as wildcards on steroids.
But you can do much more with regular expressions. Any email address, to be exact. NET languageor a multitude of other languages. Regular Expressions Quick Start If you just want to get your feet wet with regular expressions, take a look at the one-page regular expressions quick start.
While you can't learn to efficiently use regular expressions from this brief overview, it's enough to be able to throw together a bunch of simple regular expressions. Each section in the quick start links directly to detailed information in the tutorial.
Complete Regular Expressions Tutorial Do not worry if the above example or the quick start make little sense to you. Any non-trivial regex looks daunting to anybody not familiar with them.
But with just a bit of experience, you will soon be able to craft your own regular expressions like you have never done anything else.
This tutorial is quite unique because it not only explains the regex syntax, but also describes in detail how the regex engine actually goes about its work. You will learn quite a lot, even if you have already been using regular expressions for some time.
This will help you to understand quickly why a particular regex does not do what you initially expected, saving you lots of guesswork and head scratching when writing more complex regexes. Replacement Strings Tutorial A replacement string, also known as the replacement text, is the text that each regular expression match is replaced with during a search-and-replace.
In most applications, the replacement text supports special syntax that allows you to reuse the text matched by the regular expression or parts thereof in the replacement. This website also includes a complete replacement strings tutorial that explains this syntax.
While replacement strings are fairly simple compared with regular expressions, there is still great variety between the syntax used by various applications and their actual behavior. If you are a programmer, you can save yourself lots of time and effort.
You can often accomplish with a single regular expression in one or a few lines of code what would otherwise take dozens or hundreds. Many applications and programming languages have their own implementation of regular expressions, often with slight and sometimes with significant differences from other implementations.
When two applications use a different implementation of regular expressions, we say that they use different "regular expression flavors". Unlike most other regex tutorials, the tutorial on this website covers all the popular regular expression flavors, and indicates the differences that you should watch out for.
Not Only for Programmers If you are not a programmer, you can use regular expressions in many situations just as well. They make finding information a lot easier. You can use them in powerful search and replace operations to quickly make changes across large numbers of files.
A simple example is gr[ae]y which finds both spellings of the word gray in one operation, instead of two. There are many text editors and search and replace tools with decent regex support. Further Reading If you're hungry for more information on regular expressions after reading this website, there are a variety of books on the subject.
Make a Donation Did this website just save you a trip to the bookstore? Please make a donation to support this site, and you'll get a lifetime of advertisement-free access to this site!4 Writing Structured Programs.
By now you will have a sense of the capabilities of the Python programming language for processing natural language. Using Expressions in DynamoDB. In Amazon DynamoDB, you use expressions to denote the attributes that you want to read from an item.
You also use expressions when writing an item, to indicate any conditions that must be met (also known as a conditional update), and to indicate how the attributes are to be updated.
In the Language of Algebra, an equation is the basic number "sentence". An equation is a mathematical expression that contains an equals sign. Click on the sentences below to translate them into equations. Loading DocCommentXchange Loading DocCommentXchange. Back in the late 90s, in the process of reading for my MA dissertation, I put together a collection of hundreds of sentence frames that I felt could help me with my academic writing later on.
I love coming up with fiction writing prompts or exercises, and I think this list is particularly good for character development. You learn a lot about someone from how they behave in their most embarrassing moments, and this is a great way to create a sympathetic character.