Can we use comma to concatenate in python?
To answer the general question first, you would use printing in general to output information in your scripts to the screen when you're writing code to ensure that you're getting what you expect. Show
As your code becomes more sophisticated, you may find that logging would be better than printing, but that's information for another answer. There is a big difference between printing and the return values' representations that are echoed in an interactive session
with the Python interpreter. Printing should print to your standard output. The echoed representation of the expression's return value (that show up in your Python shell if not 1. PrintingIn Python 2, we had print statements. In Python 3, we get a print function, which we can also use in Python 2. Print Statements with Commas (Python 2)The print statement with commas separating items, uses a space to separate them. A trailing comma will cause another space to be appended. No trailing comma will append a newline character to be appended to your printed item. You could put each item on a separate print statement and use a comma after each and they would print the same, on the same line. For example (this would only work in a script, in an interactive shell, you'd get a new prompt after every line):
Would output:
Print FunctionWith the built-in print function from Python 3, also available in Python 2.6 and 2.7 with this import:
you can declare a separator and an end, which gives us a lot more flexibility:
The defaults are
2. String ConcatenationConcatenation creates each string in memory, and then combines them together at their ends in a new string (so this may not be very memory friendly), and then prints them to your output at the same time. This is good when you need to join strings, likely constructed elsewhere, together.
will print
Be careful before you attempt to join in this manner literals of other types to strings, to convert the literals to strings first.
prints
If you attempt to concatenate the integer without coercing it to a string first:
This should demonstrate that you should only ever attempt to concatenate variables that are known to be strings. The new way of formatting demonstrated next handles this issue for you. 3. String InterpolationThe formatting you're demonstrating is the old style of string interpolation, borrowed from C. It takes the old string and one time creates a new one. What it does is fairly straightforward. You should use this when you may seem likely to building up a fairly large template (at 3+ lines and 3+ variables, you definitely should be doing it this way). The new way of doing that would be to do this (using the index of the arguments):
or in python 2.7 or 3 (using the implied index):
or with named arguments (this is semantically easy to read, but the code doesn't look very DRY (i.e. Don't Repeat Yourself))
The biggest benefit of this over
New in Python 3.6, format literalsPython 3.6 will have format literals, with a more elegant syntax (less redundancy). The simple syntax is something like:
The format literals can actually execute code in-place: There are few guarantees in life: death, taxes, and programmers needing to deal with strings. Strings can come in many forms. They could be unstructured text, usernames, product descriptions, database column names, or really anything else that we describe using language. With the near-ubiquity of string data, it’s important to master the tools of the trade when it comes to strings. Luckily, Python makes string manipulation very simple, especially when compared to other languages and even older versions of Python. In this article, you will learn some of the most fundamental string operations: splitting, concatenating, and joining. Not only will you learn how to use these tools, but you will walk away with a deeper understanding of how they work under the hood. Splitting StringsIn Python, strings are represented as Have you guessed how those two features of strings relate to splitting functionality in Python? If you guessed that What about string immutability? This should remind you that string methods are not in-place operations, but they return a new object in memory. Splitting Without ParametersBefore going deeper, let’s look at a simple example: >>>
This is actually a special case of a Another feature of the bare call to >>>
The first thing to notice is that
this showcases the immutability of strings in Python: subsequent calls to The second—and the main—thing you should see is that the bare Specifying Separators
Where there are multiple consecutive separators (such as between “this” and “is” and between “is” and “my”), the first one will be used as the separator, and the subsequent ones will find their way into your result list as empty strings. Limiting Splits With Maxsplit
>>>
As you see above, if you set What happens
when you give a negative number as the
You were recently handed a comma-separated value (CSV) file that was horribly formatted. Your job is to extract each row into an list, with each element of that list representing the columns of that file. What makes it badly formatted? The “address” field includes multiple commas but needs to be represented in the list as a single element! Assume that your file has been loaded into memory as the following multiline string:
Your output should be a list of lists:
Each inner list represents the rows of the CSV that we’re interested in, while the outer list holds it all together. Here’s my solution. There are a few ways to attack this. The important thing is that you used
We call The first
element is What does The final part might be new: In all, we iterate through a list of strings, where each element represents each line in the multiline input string except for the very first line. At each string, we call Concatenating and Joining StringsThe other fundamental string operation is the opposite of splitting strings: string concatenation. If you haven’t seen this word, don’t worry. It’s just a fancy way of saying “gluing together.” Concatenating With the + OperatorThere are a few ways of doing this, depending on what you’re trying to achieve. The simplest and most common method is to use the plus symbol ( >>>
In keeping with the math theme, you can also multiply a string to repeat it: Remember, strings are immutable! If you concatenate or repeat a string stored in a variable, you will have to assign the new string to another variable in order to keep it. >>>
If we didn’t have immutable strings, Another note is that Python does not do
implicit string conversion. If you try to concatenate a string with a non-string type, Python will raise a >>>
This is because you can only concatenate strings with other strings, which may be new behavior for you if you’re coming from a language like JavaScript, which attempts to do implicit type conversion. Going From a List to a String in Python With .join()There is another, more powerful, way to join strings together. You can go from a list to a string in Python with the The common use case here is when you have an iterable—like a
list—made up of strings, and you want to combine those strings into a single string. Like This is a bit of a trick question. Remember that when you use >>>
Here, we join each element of the How could you make the output text more readable? One thing you could do is add spacing: >>>
By doing nothing more than adding a space to our join string, we’ve vastly improved the readability of our output. This is something you should always keep in mind when joining strings for human readability.
>>>
Using our web scraping tutorial, you’ve built a great weather scraper. However, it loads string information in a list of lists, each holding a unique row of information you want to write out to a CSV file:
Your output should be a single string that looks like this:
For this solution, I used a list comprehension, which is a powerful feature of Python that allows you to rapidly build lists. If you want to learn more about them, check out this great article that covers all the comprehensions available in Python. Below is my solution, starting with a list of lists and ending with a single string:
Here we use Tying It All TogetherWhile this concludes this overview of the most basic string operations in Python (splitting, concatenating, and joining), there is still a whole universe of string methods that can make your experiences with manipulating strings much easier. Once you have mastered these basic string operations, you may want to learn more. Luckily, we have a number of great tutorials to help you complete your mastery of Python’s features that enable smart string manipulation:
What happens when you join two strings together using the comma in Python?You can concatenate a list of strings into a single string with the string method, join() . Call the join() method from 'String to insert' and pass [List of strings] . If you use an empty string '' , [List of strings] is simply concatenated, and if you use a comma , , it makes a comma-delimited string.
How do I concatenate in Python?Use the + operator. str1="Hello". str2="World". print ("String 1:",str1). print ("String 2:",str2). str=str1+str2.. print("Concatenated two different strings:",str). What is the difference in using a comma or plus (+) when performing concatenation?concatenation means you are combining both variables(only strings) into one. But when you use comma it prints both the output separately but you can't see it on the output console. concatenation can only be made between strings.
What is the best way to concatenate strings in Python?One of the most popular methods to concatenate two strings in Python (or more) is using the + operator. The + operator, when used with two strings, concatenates the strings together to form one.
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