Python string concatenation not working

Python string concatenation not working. This type of error may pass unnoticed, causing hard-to-debug issues in your code. – Keith May 1, 2023 · How can I make it work? It should skip the missing value and only concatenate the non-missing values. edited Dec 4, 2019 at 19:24. title”. May 25, 2024 · Another way of concatenating multiple strings in Python is just by writing string literals consecutively: a = "Red""Green""Blue" print(a) RedGreenBlue. The Python . Sep 5, 2023 · 1. 2. It is to take an iterable of strings, for a example, a list, and join them all together. Jun 20, 2019 · The one that exists is 'y_trainvalid' (39209, 43), which stands for 39209 images in 43 classes. This new way of formatting strings lets you use embedded Python expressions inside string constants. Format method in String contains curly braces {} as placeholders which can hold arguments according to position or keyword to specify the order. ### Overview of String Concatenation Techniques. The fact that you can print them individually doesn't make a difference, you can't concatenate a string and a tuple, you have to convert either one of Remember, being proficient in string concatenation is not just about knowing the syntax but also about knowing when and how to use it to write better, more efficient Python code. The default version takes strings of the form defined in PEP 3101, such as “0 [name]” or “label. I have a list of pd. format() method works similar to f-strings in that it uses curly braces to insert variables into strings. Using any form of string concatenation for huge or many strings would be bad practice just as using str. If you want to append to a string you have as variable, simply use If you want to append to a string you have as variable, simply use Feb 19, 2013 · I'm working on a python project. It’s one of the basic built-in data types, so knowing how to work with strings in Python efficiently is key to becoming a good programmer. What you showed here is the concatenation of string with string, not string with bool. Like this (a, b and c are strings): something = a + b + (c if &lt;condition&gt;) But Python does not Feb 20, 2022 · Please always include the numpy tag when asking NumPy questions. 7. In Python, text data is represented by the string data type. This mistake introduces a subtle bug into your programs. split(). what I am working on should input the vocabulary from a set of text files at start up, generating the same result as the first program. For the readability of the logs I need to concatenate strings, but at the beginning and not at the end. To concatenate, or combine, two strings you can use the + operator. When you however concatenate it with a string, it is time to keep its promise, and it thus presents a string, and it no longer can thus, when needed, check the active language. String concatenation takes place on the next line in python. >>> print ("red" + " " + str (13)) red 13. Nov 5, 2014 · 6. Here’s a simple example to give you a feel for the feature: Python. valList is probably the result of calling readlines() on a file object, so each element in it will have a trailing \n. The case where you're just formatting things as a string is the simple case, but f-strings or format() allow for lots of detailed controls -- padding, format conversion, etc. Mar 19, 2024 · In Python, string concatenation is the process of combining multiple strings into a single string. mpg) Oct 26, 2017 · They are not fully equivalent however. Strings are Arrays. answered Nov 12, 2010 at 16:20. 0. Here’s an example of the + operator in practice: Jun 21, 2019 · dhke - as far as I can tell, all of the data coming through is numeric and in the expected format. def mod3 (ad): result = "" testAd =ad. >>> f'Hello, {name}!' 'Hello, Bob!'. g. Actually, "". format(color=self. You can filter out the are and concatenate with "". Dec 18, 2008 · Be wary of concatenating strings in a loop! The cost of string concatenation is proportional to the length of the result. If a single space is needed, change the string compared with value in line 4. concatenation of Apr 4, 2019 · They both are not working for me. 01:12 I press Enter to confirm we get the string batman stuck together. split() work on the original string, not on the list result of the first call to . Because Python doesn’t find the separating comma, it triggers automatic string literal concatenation, joining both items in a single string, 'SculptingGardening'. The first and most basic way to concatenate two or more Python strings is by using the + operator. That means that every concatenation of a string results in a new string object being created and two (the source objects) being thrown away. join() is that adding strings together means creating a new string (and potentially destroying the old ones) for each addition. In many programming languages, you have to do a lot of the heavy lifting by yourself. join to 'em will break. Concatenate a String and an Int in Python with format. Mar 27, 2023 · Python String Concatenation: An Introduction: A tutorial on DigitalOcean introducing string concatenation in Python with examples. So when you know you need to concatenate multiple strings SQLite 3. In Python, Strings are arrays of bytes representing Unicode characters. For a larger number of strings, the standard Python approach Oct 2, 2021 · No you can NOT concatenate string with a bool value. But we can't do it for ints and, as a result, this code fails when a=b=0 and the polynomial reduces to an integer constant! But: "All of them are based on the string methods in the Python standard library. join is not to concatenate two strings. join([string, "World"]), however, you would probably Sep 3, 2015 · The problem here is that the format method is only being called for the final string in the 3 strings being added together. String. – String literals prefixed by r are meant for easier writing of regular expressions. join will be faster with a list, than with a generator expression. Nov 25, 2018 · The "+" operator is using for concatenate strings, adding numbers, etc. Now the last task was to concatenate them with Sep 4, 2016 · Quoting the string literal documentation (from the section on raw string literals): String quotes can be escaped with a backslash, but the backslash remains in the string; for example, r"\"" is a valid string literal consisting of two characters: a backslash and a double quote; r"\" is not a valid string literal (even a raw string cannot end in Mar 5, 2023 · The main problem is that _('translatethis') is not a string, but something that promises, when necessary, to be a string. Memory allocation is expensive enough to make this matter a lot. giant_concat_df = pd. May 29, 2023 · The simplest way to append to a string in python is to use the + (plus) operator. 9. Recap: String Concatenation in Python In this comprehensive guide, we’ve explored various methods to concatenate strings in Python, a fundamental operation that comes in handy in a wide range of programming scenarios. See full list on pythontutorial. This is an easy and convenient way to slice a string using list slicing and Array slicing both syntax-wise and execution-wise. May 14, 2017 · I'm working with SymPy, so I have code like this: 'Consider the polynomial ' + (a*x**2 + b*x + c) This works 99% percent of the time because we overloaded the '+' for SymPy expressions and strings. 55. Instead of functioning as a mathematical addition, in Python the + operator is used to concatenate strings together. This f-string feature is useful for inserting quick debugging checks in your code. If you can use list comprehension, that's the easiest and fast as well. Try this instead: Sep 24, 2016 · In most cases it makes more sense to use str. In this course you’ll learn some of the most fundamental string operations: splitting, concatenating, and joining. For three strings of length 100000, concatenation is 0. 4 but about version 2. Use them based on your requirements. format() method to combine a string and an integer in Python. So i am a fairly new python user and i'm trying to make a game of rock paper scissors where you can either play against the AI or a simulation vs 2 real people (local gamee) but i keep getting this error: TypeError: can only concatenate str (not "tuple") to str Here's the line(s) of code where the problem occured: Oct 14, 2015 · Python string concatenation not working as expected. May 21, 2024 · Returns a tuple (obj, used_key). In Python, indexing syntax can be used as a substitute for the slice object. Try this: Feb 19, 2024 · learn python. Python String formatting can be done in several ways. Oct 27, 2020 · Python string concatenation not working as expected. \n is an escape sequence that only works in string literals. This means that you can use it to append one string to another. df. 98911 times faster than f-strings. Optimized list append seems very good in most situation. It’s available in versions as far back as Python 2. 7, Hatem Nassrat has tested (July 2013) three concatenation techniques where + is faster when concatenating less than 15 strings but he recommends the other techniques: joinand %. encode()` method to convert the string to bytes. you can also use f-strings if you have python 3. (Mind you - if you're storing silly stuff in a DF/array, then that's a whole different problem in itself :p) Jan 6, 2016 · 9. Consider os. You can make it even more readable by using format with named arguments: def display_car(self): print "This is a {color} {model} with {mpg} MPG. One of their features is that backslash characters do not have to be escaped. >>> string1 = "I like". Here, "". For example, let’s define two variables of type string and concatenate them using the + operator. For a larger number of strings, the standard Python approach Mar 30, 2020 · I am new to Python. Python can sometimes optimize this away, but str. Concatenate a list of strings on new lines. Nov 2, 2018 · Here is a simple illustration. There are numerous ways of concatenating strings in Python. str. encode('hex') or a one-liner using str. Apr 13, 2016 · A javascript string is immutable so concat can only return a new value, not change the initial one. concat(list_of_dfs,0) You can use turn all of the dataframes to a list of dictionaries and then make a new data frame from these lists (merged with chain) Nov 13, 2010 · The reason for using str. join means that, join the strings returned by the generator expression with no filling character. So as you can see here, I’m using the plus operator ( + ), which if you use it with strings, it concatenates them together, so it’ll literally stick bat and man together without any space in between. A start, end, and step have the same mechanism as the slice () constructor. Mar 12, 2013 · Well I would agree that a CS101 student would probably not get this, but this isn't a difficult concept for those a little ways into python. For just two strings, big-O is irrelevant, as there is nothing you can do to improve it. Feb 25, 2019 · The problem is that you are not working with strings. Query: SELECT CONCAT(locationname, '<p>') FROM location; May 17, 2019 · if some_file_name isn't a string, the f string or format method are easier to use. Nov 7, 2012 · The default is to return None, but by specifying an empty string your concatenation will work even if CDO_TBLPATH is not defined. concatbefore('it works') Finally, I want that str has the following value : 'it works'+'bla[]'. Some languages will optimize concatenation to the most recently allocated string, but it's risky to count on the compiler to optimize your quadratic algorithm down to linear. net Jan 5, 2024 · Last Updated : 05 Jan, 2024. 5. python string concatenation confusion. format, which will take care of casting the variables to string for you: def info_msg(self): return "{0}#{1}#{2}". The return value used_key has the same meaning as the key parameter to get_value(). This functions basically concatenate many strings and create a dictionary with a single entry that contains the concatenated string. May 18, 2023 · Create a string containing line breaks. So if you just use the standard library you can write code that doesn't depend on numpy. You can create a string result where you can concatenate your each iteration result and print that. Another way is to use the `bytes. join() would be bad practice for short and few strings, in my own opinion. Split a string into a list by line breaks: splitlines() Remove or replace line breaks. In Python, on the other hand, you have several built-in functions in the standard library to help Jun 16, 2017 · The concatenation itself doesn't add the \n for sure. See this question for details about the difference between a string and the string's representation. But that's the beauty of SO, the people will decide. However, Python does not have a character data type, a single character is simply a string with a length of 1. decode()` method to convert the byte array to a string. For three strings of length 1000000, concatenation is 0. Use it to quickly convert numbers, decimals, and other objects into Dec 11, 2021 · In the next section, you’ll learn how to use the . Not only will you learn how to use these tools, but you’ll walk away with a deeper understanding of how they work under the hood in Python. (this current comment is just to confirm the @tonfa's comment above). not related to your problem but take advantage of the fact that if char in string tests for occurence to simplify your conditions. When I use f-strings formatting, the result is aggregating the whole column Amount as a series instead of using the value of a particular row for string concatenation: df['Description'] = f'Amount is {df["Amount"]. Aug 20, 2013 · I think you see that both versions are more readable than your's with string concatenation. However, not all methods can concatenate strings and numbers. If you have two strings (string1 and string2) you can concatenate them using the expression string1 + string2. An option might be to work with a lazy object Python string concatenation not working as expected. The first thing to notice is that this showcases the immutability of strings in Python: subsequent calls to . 0 and newer supports CONCAT function: concat (X,) The concat () function returns a string which is the concatenation of the string representation of all of its non-NULL arguments. Python includes an operator that can be used to concatenate, or combine, two strings together, one after another. The second—and the main—thing you should see is that the bare . If you need 1 to 10 concatenation (average) with length 1 to 100, list append, '+' both takes same (almost, note that times are scaled) time. 60201 times faster than f-strings. in your case you trying to add two integers but in your dictionary "salaries" the values are strings. Python also provides the format () method to concatenate multiple strings together. split () for word in testAd: modAd = "" i = 0 for char in word: if i == 0: modAd For three strings of length 10000, concatenation is 1. join, then all the elements will be joined by ,. You'll have to do your own processing of such escapes Apr 4, 2019 · They both are not working for me. astype(str)}'. Why am I getting this python concatenation error? 3. Out[2]: Product Id Amount Description. I'm doing logs of what happen on my project. Here is what I want to do : str=''. Jun 27, 2019 · Because the format method is only applied to the last string within the double quotes e. Concatenate strings in Python? 0. Feb 28, 2021 · With Python you can concatenate strings in different ways, the basic one is with the + operator. – Nov 5, 2014 · 6. So, append + " " to your result variable as well. hidden) Share Mar 27, 2023 · Method 2: Using the List/array slicing [ :: ] method. join, like this. content, self. I had a line of code to print strings along with variables. Aug 31, 2012 · 0. If you prefix with print, you'll get what you expect. Nov 13, 2010 · The reason for using str. May 7, 2024 · Strings in Python or string data type in Python can be formatted with the use of format() method which is a very versatile and powerful tool for formatting Strings. format(info, self. Output with print() without a trailing newline. Mar 28, 2011 · Python string concatenation not working as expected. With join you would need something like ' '. To do what you are attempting, you need to treat x as a string, and append the string literals '0' and '1' to it. String concatenation is the process of joining two or more strings together and forming one single string. It also calls str() function when an object argument is used as field replacement. : DB_PREFIX = 'prod_' INDEX_PREFIX = 'index_' CRM_IDX_PREFIX = DB_PREFIX + INDEX_PREFIX + 'crm_' But most of the cases the format function and operators are used to concatenate with variable content Nov 2, 2022 · Using this method will convert a number into a string. Concatenate strings and numbers . list_of_dfs = [df_a, df_b] And instead of running. I decided to instead, assign what I had in the print statement to a variable, so I could print that information elsewhere. Python itself has an array module that is quite different from these arrays. If all arguments are NULL, then concat () returns an empty string. What’s Included: Jun 6, 2020 · 5. If you have ",". __add__ because + treats strings specially in both Python 2 and Python 3. While it's true that __add__ special method is normally used to implement the + operator, + ( BINARY_ADD bytecode instruction) does not call str. On these archives, the number set to 1 if it matches the class and 0 if it doesn't. The str () method simplifies the process of converting different types of data into string objects. . Call variable from two concatenated strings Python. join('a', '/b'), which actually returns /b. Unable to concatenate strings in Python2. Mar 22, 2021 · String manipulation is one of those activities in programming that we, as programmers, do all the time. . Jun 6, 2020 · 5. String concatenation in Python is the process of joining two or more strings end-to-end to create a new string. the issue is that the result is just a print of the text file content, instead of using it to generate random sentence, and it prints Jul 21, 2020 · 1 Answer. Concatenate. head(3) df2 = df2. >>> string2 = "Python". You need to add spaces after each addition of words. For this, we invoked the join() method on a string containing the space character and passed a list of all the input strings. join, make sure path components don't unexpectedly have a leading slash. Sorted by: 1. In the above example, we have concatenated three strings using the space character. Python has many built-in data types. color, model=self. One way is to use the `str. Like many other popular programming languages, strings in Python are arrays of bytes representing unicode characters. args and kwargs are as passed in to vformat(). Dec 26, 2023 · There are a few ways to work around the limitation of not being able to concatenate a string to a byte array. Close the parentheses. Jul 23, 2019 · I have tried using single quotes, and looking up correct syntax for string concatenation, but I think that something different happens when you are concatenating a string and a str (var) function. Looping leads you straight to the land of N-squared. Previous articles (check references) have already explored this issue of taking a list of strings and concatenating all elements together. When concatenating strings, it’s important to remember that strings are immutable, meaning the original strings are not modified; instead, a new string is created. Python String Concatenation - Unexpected Behavior. Suppose input1 is . for(bla in bli): str+=bla. The point of str. We can use the plus symbol + between two strings to concatenate them together into a single string, making it much simpler to build more complex strings and outputs. The new label archive I'm trying to add is 'new_file_label' (23, 43). You should use the class StringBuilder instead. The + operator is commonly used for this purpose. Jackie Wilson 4 Lessons 18m basics python. path. Conclusion. 7+ like so: If the intention is to just concatenate it. you can convert the value to int, adding the numbers and then convert to string to store the value. join() but there are times when concatenation is just as viable. Newline character \n (LF), \r\n (CR + LF) Triple quote ''', """. You should either apply the format operation AFTER you have concatenated the strings, or use a single string format that accepts line breaks (so you don't have to concatenate strings in the first place). You converted that boolean value to string first so it's not a boolean value anymore. The last time that comes through before the code bombs is 1495477260000, so not sure why adding 60K to it wouldn't work May 23, 2018 · The OP asked for Python 2. Python Concatenating Strings. You can get around this issue with a 'manual' concatenation, in this case your. Once I assigned it to a variable it won't concatenate the string with the other variables. I happen to think its pretty elegant, though not necessarily the most efficient. Apr 5, 2021 · TypeError: can only concatenate str (not "NoneType") to str How can I concatenate my function age ( age is an input() function declaration) to a string or strings? The age function is an input() and I want to add it to the appropriate name or string. Jul 21, 2020 · 1 Answer. Jan 6, 2016 · I guess that, if all the terms to concatenate are constants, the concatenation with the + operator might be optimized by python for performance. So, this would be OK: r'C:\Program Files (x86)\LibreOffice 5\program\soffice. answered Dec 4, 2019 at 19:12. Jun 13, 2020 · 1. A\tB\r\n C\t\r\n Here, A, B, C are ordinary words and \t is tab. This is a special Python method that works with many different types of objects. join() quickly becomes clearer, more obvious and significantly faster. get_value(key, args, kwargs) ¶. You are first creating an empty tuple for x, and then overwriting that with an integer value later. answered Aug 31, 2012 at 15:33. Mar 15, 2024 · String Concatenation using f-string = Hello World Pankaj age is 34 and d=Data[10] Python f-string is cleaner and easier to write when compared to format() function. Oct 24, 2021 · Yes, because you are using " "which is not an empty string. + is a lot more variable in how it behaves across types, and offers far less control. String Concatenation. Here's a sample of both of them: print(y_trainvalid) This new way of formatting strings lets you use embedded Python expressions inside string constants. If you just want to concatenate two strings then use the concatenation operator: string + "world". You can use the + operator, or use a built-in function like str. If you want the whole string result, you should call the format method on only one string: Jun 11, 2020 · sorry for not specifying, the first program simply generates the sentence. 5. The outcome should look like this: Oct 18, 2023 · When Python runs the f-string, it builds an expression-like string containing the variable’s name, the equal sign, and the variable’s current value. ". join is a much better way to add a common delimiter to a list of items. :-) – Jun 30, 2023 · The first string is: Python The second string is: For The third string is: Beginners The concatenated string is: Python For Beginners. a + b is fine; you can't amortize the growth, so you can just concatenate them, performing one allocation for the new string, and two copies into that single allocation, one from each source. 44. Feb 28, 2021 · Python also provides the format () method to concatenate multiple strings together. join , which is faster than concatenation: There are two solutions from Concatenate tab-delimited txt files vertically. Ex. May 25, 2019 · obviously objects are strings - Not quite true they're objects that aren't of a numpy type they could be (although unlikely in most cases) be anything rather than string - hence applying str. Square brackets can be used to access elements of the string. 7, so Using a string. input() does not take a string literal, it takes the text the user inputs and doesn't do any processing on it so anyone entering \ followed by n produces a string of two characters, a backslash and the letter n, not a newline. split () for word in testAd: modAd = "" i = 0 for char in word: if i == 0: modAd Jan 28, 2013 · The console is printing the representation, not the string itself. concat doesn't change the string it is called on - it returns a new string which is the string and the argument concatenated together. split() call extracts the words in the sentence and discards any whitespace. head(3) Feb 8, 2014 · Strings are immutable objects in Python, so you cannot modify existing strings. These pieces were written a while ago and in Python 2, so I was curious to see the differences with the most recent version of Python 3, currently at 3. 27484 times faster than f-strings. Feb 3, 2020 · Python 3. By the way: string concatenation using concat or += is not very performant. As I am getting errors, I began to investigate: From two of the DataFrames in the list, I took a subset of rows and columns; and reset the index: df1 = all_predictions[1] df2 = all_predictions[2] df1 = df1. Dec 29, 2016 · I want to concat few strings together, and add the last one only if a boolean condition is True. join () to concatenate two strings. In this article, we’ll show you Python string fundamentals with plenty of hands-on examples. The first functions does it directly on the entry "d [key] += str (num)" and the second on a string "out_str += str (num)". DataFrames all_predictions that I want to concatinate. 6. X\tY input2 is. "{} = {}". model, mpg=self. It negates the need to have to check for being on the last item before adding the delimiter, or in your case attempting to strip off the last one added. Super-simplified, the representation is what you'd type in source code to get that string. With indent. Test setup Aug 31, 2010 · does not work. As you can see, this prefixes the string constant with the letter “ f “—hence the name “f-strings. Python uses + to concatenate strings because that's how core developers of Python defined that operator. A simple example is shown below: Oct 24, 2017 · An other option is to use str. May 25, 2013 · In python you can loop over the string itsellf, so no need of slicing in your example: hs = '' for c in s: hs += c. concatenating strings? 1. ”. So if you're mixing these methods, or converting from string concatenation to os. exe' However, that wont work for a string ending in backslash: r'\' - this is a syntax error; So, this is Sep 4, 2016 · If you have a string list available, string 'join' method is best and fastest. gp am vk vj ja dc bv jd rc us