Concatenate string in r

Concatenate string in r

How can two strings be concatenated?

  • Enter two custom strings. Store it in a variable, for example str1 and str2. Here you need to merge str2 with str1
  • Find the length of the string str1 and store it in a variable, say i = length_of_string.
  • Go to the end of str2 and copy each character from index i to str1.

How to concatenate strings into one?

An easy way to concatenate multiple strings into one is to use the +: operator, and the + operator works with both string literals and string variables. Example: Similar to the + operator, you can use the += operator to combine multiple strings into one:.

What is string r?

R Strings: Any value enclosed in single or double quotes in R is treated as a string. Internally, R stores any string in double quotes, even if you construct it in single quotes.

What is concatenation in programming?

Concatenation, in the context of programming, is the process of joining two strings together. The term concatenation literally means to put two things together. Also known as string concatenation.

How can two strings be concatenated together

The add function appends the string add(variable) to the end of the initialization string. This is the easiest way to merge 2. The + operator simply adds the string 2 and returns the concatenated string.

How do I concatenate strings in Python?

In Python you can concatenate strings in several ways. The method to use depends on the stage or source of the channel. Here are the ways to concatenate strings in Python: Use + (plus) Use the concatenation operator + =. The join method is for iterators. Using StringIO. Space between string literals.

:brown_circle: How do you combine strings in Excel?

To insert a space or other character, you can insert a string in a formula. Select the cell where you want to merge data. Type = (equal sign) to start the formula. Click in the first cell. Enter the & operator. Enter a string for the desired character between words, for example:.

How can two strings be concatenated in 1

Use CONCATENATE, one of the text functions, to concatenate two or more strings of text on one line. Important: In Excel 2016, Excel Mobile, and Excel for the web, this function has been replaced by the CONCAT function. While the CONCATENATE function is still available for backwards compatibility, you should use CONCAT from now on.

:eight_spoked_asterisk: How can two strings be concatenated in c

A common task to do with any language is to join or combine strings. This process is known as chaining. The best way to describe this is to merge two separate strings stored in the interpreter into one string.

:diamond_shape_with_a_dot_inside: How do you find the length of a string in C?

To find out the length of a string in C++ programming you have to ask the user for a string and then use the strlen function in the library to find the length of that string and the value of the length of the pipe display on the screen of output As shown below. The program is displayed.

What is concatenate function in C?

  • Syntax. Pointer to the string you want to change.
  • Return. The strcat function returns a pointer to s1 (where the resulting concatenated string is found).
  • Header required.
  • Refers to
  • example straight.
  • Similar features:

:eight_spoked_asterisk: What is string function in C?

String functions in C. The standard library of the C programming language has a number of functions that implement operations on strings (strings of characters and bytes). Various operations such as copy, merge, segment and search are supported.

How can two strings be concatenated in 3

Method 3: Using the "+" operator syntax: string newstring = start-string + append-string This is the simplest method of combining two + operators, simply adding two strings and returning the concatenated string.

How to concatenate cells and retain date format?

  • (1) Check the Merge Columns option in the Merge Selected Cells section according to the following options.
  • (2) Check the separators option in the "Specify separators" section (in your example, they will check the "Spaces" option).
  • (3) Specify where you want to place the concatenation result.

:diamond_shape_with_a_dot_inside: How do I change cell names?

  • Select the cell you want to name.
  • Go to the name field and enter the desired name.
  • Press Enter on your keyboard.

How to concatenate only visible cells in Excel?

  • Hold down Alt+F11 to open the Microsoft Visual Basic for Applications window.
  • Click Insert > Module and paste the following code into the module window.
  • Then save and close this code, go back to your worksheet and enter the following formula: =concatenated(B2:B10,)(B2:B10 is the filtered data range you want to concatenate.

Series 24

How to concatenate first letters of names/cells in Excel?

  • Click in the first cell of the column where you want the combined names to appear (C2).
  • Type an equal sign (=).
  • Select the cell with the first name (A2) followed by an ampersand (&)
  • Select the cell with the last name (B2).
  • Press Enter.

:eight_spoked_asterisk: How to concatenate strings in excel

1. Select the range you want to merge, and click Kutools > Merge & Split > Merge Rows, Columns or Cells without data loss. See screenshot: 2. In the dialog box that pops up, please do as follows: (1) In the section "Merge selected cells with the following options", specify the merge option according to your needs.

:eight_spoked_asterisk: How to put concatenate formula in Excel?

  • Select a blank cell where you want to place the concatenation result, and enter the formula =CONCATENATE(B1:J1 &,).
  • Highlight B1:J1 & in the formula and press F9 to replace the cell references with the contents of the cell.
  • Remove the braces {and} from the formula and press Enter. See screenshot:

How to combine strings in Excel?

  • Select the cell where you want to enter the formula.
  • Type =CONCATENATE( in this cell or in the formula bar.
  • Hold down the Ctrl key and click each cell you want to merge.
  • Release the Ctrl key, type a closing parenthesis in the formula bar and press Enter.

How to concatenate strings into one column

Select the cell where you want to paste the combined data. Enter = and select the first cell you want to merge. Type and use quotation marks with spaces. Select the next cell you want to merge and press Enter. An example formula would be = A2 & & B2. Select the cell where you want to paste the combined data. Type = CONCADOR (.

:brown_circle: How do you combine two columns together in Excel?

How to combine two pillars in 4 easy steps. Download and install Merge Cells for Excel. Select all the cells in the two columns you want to combine and go to the Data tab. Click the Merge Cells button to launch the add-in. In the Merge Cells dialog box, select the following options: Merge Selected Cells: Line by Line.

:diamond_shape_with_a_dot_inside: How to merge two columns into one in Excel?

  • Add a new column to your table. Place your cursor in the column header (in your case column D), right click and select Paste.
  • Type the following formula in cell D2: =CONCATENATE(B2, ,C2) B2 and C2 are the addresses of the first and last names, respectively.
  • Copy the formula to all other cells in the Full Name column.
  • So they have combined the names of two columns into one, but the formula remains the same.
  • Now you need to convert the formula to a value so that you can remove the unnecessary columns from the Excel sheet.
  • Delete the First Name and Last Name columns that you no longer need.

:brown_circle: How to combine columns separated by comma in Excel?

1. Select the column list you want to convert to comma separated list, and click Kutools > Merge & Separate > Merge Rows, Columns or Cells without data loss. 2. In the "Combine Columns or Rows" dialog box that opens: 3. Click OK.

On-Chain Governance

:brown_circle: How to join two columns in Excel?

  • The first step is to download and install Excel Ultimate Suite.
  • After installing the package, select 2 or more columns to merge.
  • In the Excel header, select Data > go to the Merge group, and then select the Merge Cells option > select the Merge Columns option from the menu.

What is the best way to concatenate strings in JavaScript?

  • + operator. The same + operator that you use to add two numbers can be used to join two strings together.
  • Array#join The Array#join function creates a new string by joining all the elements of an array. The first parameter to be bound is called the separator.
  • String#concat JavaScript strings have a built-in concat method.

:brown_circle: How do I combine strings in Java?

Using the + operator is the most common way to concatenate two strings in Java. You can specify a variable, a number, or a string literal (always enclosed in double quotes). For example, to combine the strings "I" and "student", you would type: I + student.

How can I compare two strings in Java?

In Java, the equalsIgnoreCase method is similar to the equals method, but more liberal than equals, comparing two strings regardless. That is, if two strings contain the same characters and in the same order, regardless of capitalization, the equalsIgnoreCase method always returns true.

Series Business Unit (SBU)

:brown_circle: How do you format a string in Java?

The Java String Format method returns a string formatted according to the specified locale, format, and arguments. If you do not specify a locale in a method, the default is used when the method is called.

How to concatenate strings into one pdf

Acrobat converts pages from different files to consecutive pages of the same PDF file. Choose Tools > Merge Files. The file merging interface appears with a toolbar at the top. Drag and drop files or emails directly into the file merging interface.

:eight_spoked_asterisk: How do you combine two PDF files together?

Merge two PDF files Open the PDF in Preview mode. Choose View > Thumbnails to display the page thumbnails in the sidebar. Select the page thumbnail to indicate where to insert another document. Choose Edit > Insert > Page from File*, select the PDF you want to add and click Open. Choose File > Export as PDF to save.

How to combine two PDF files together?

1) In the "Options" dialog box, specify the necessary conversion options and click "OK". 2) When you are done organizing the pages, click Merge. The status window shows the progress of the file conversion. Some native applications start and close automatically.

Regex starts with

What is the best free software to combine PDF files?

Adobe Acrobat is undoubtedly the most popular application for viewing, editing and modifying PDF files. Acrobat XI is Adobe's leading software package for combining and merging PDF documents. As expected, it offers next-level PDF Merge that allows you to merge multiple PDF files into a single PDF file.

:diamond_shape_with_a_dot_inside: How to combine multiple PDFs into 1?

  • Choose Tools > Organize Pages > Insert > Blank Page.
  • In the Insert Pages dialog box, specify where you want to insert a blank page.
  • You can also use the context menu to add a blank page between pages. Choose Tools > Organize Pages to view a thumbnail of the page. On the page

:diamond_shape_with_a_dot_inside: How to concatenate strings into one text

Easily merge cells with the same value with Kutools for Excel (a few clicks). Select the column with the same value that you want to merge and click the "Primary Key" button. ) Select the column whose cells you want to merge, click the "Merge" button, and then specify the separator in the context menu (here I specify a comma). ) Click OK.

Why is the concatenate Excel formula not working?

  • The cells are formatted as text. Now let's see the solutions for the above reasons why Excel formula is not working.
  • You accidentally typed CTRL + `. Often in Excel, when they are in a hurry, they tend to enter keys that are not needed, and this:
  • The values ​​are different and the result is different.
  • Do not put numbers in double quotes.

How do I merge data from two columns?

Download and install Merge Cells for Excel. Select all cells in the two columns you want to merge and go to the Data tab. Click the Merge Cells button to launch the plugin. In the Merge Cells dialog box, select the following options. Merge selected cells: line by line.

:diamond_shape_with_a_dot_inside: How to concatenate columns with Alt?

  • (1) Check the "Merge Rows" option in "Merge Selected Cells" based on the following options.
  • (2) Activate New Rule option in Specify separators section
  • (3) Activate one of the required parameters in the Parameters section. In my case, I check the "Remove content from list boxes" box.
  • (4) Click the OK button.

How to concatenate strings into one file

An easy way to concatenate multiple strings is to use the + operator: s = String + Concatenation Print(s) Code Language: PHP (php) And the + operator works for both string literals and string variables.

What is string concatenation?

String concatenation is a way to add two or more strings to a single string, either character by character or with a special transfer character. There are many ways to concatenate strings.

Combining functions

How to concatenate strings into one table

Using this function on individual lines is the same as using the & operator. The Concat function concatenates the result of a formula applied to all records in a table into a single row. Use this function to group strings into an array, much like the Sum function for numbers.

How do you concatenate a table with multiple columns in SQL?

The merge function merges a mixture of individual rows and a table of rows with a column. When used with individual strings, this function is equivalent to using the & operator. You can use a formula containing the ShowColumns function to create a single-column array from a multi-column array.

What is the use of concatenation in MySQL?

Concatenates individual strings and strings in arrays. The Concat function concatenates the result of a formula applied to all records in a table into a single row.

:brown_circle: What are the examples of concatenation in tableau?

Examples 1 Combination of a function and the & operator. For these examples, set the Text property of the Label control to the formula in the first column of the following table. 2 Join into a single column table. 3 concat function 4 Cut the end. 5 Divide and merge everything together.

Series 3

:diamond_shape_with_a_dot_inside: What does R mean in a string?

2 Answers The r means that the string should be treated as a raw string, which means that escape codes are ignored.

:diamond_shape_with_a_dot_inside: What is a character string in R?

The class of an object containing strings in R is called "char". A string in R can be enclosed in single or double quotes. You can create an empty string with empty_str = or an empty character vector with empty_chr = character(0).

How do I convert a string to an integer?

The easiest way to convert a string to an integer is to use the Integer class and then call the parseInt method. There are two methods to convert a string to an integer. One method is to use a method that returns a primitive int value.

What is an example of a string?

A string is a data type used in programming; However, it is used to represent text, not numbers. It consists of a string of characters, which can include spaces and numbers. For example, the word "hamburger" and the sentence "I ate 3 burgers" are strings.

Series B financing

What is string r in java

There are two ways to create a Java String object: By String Literal: A Java string literal is created with double quotes. For example: String s="Welcome" By new keyword: A Java string is created with the keyword "new". For example: String s=new String("Welcome").

What does exactly does in Java?

  • Definition and Use. The substring method extracts characters from a string between two specified indexes and returns a new substring.
  • Browser Compatibility
  • Syntax
  • Parametric values. The position to start the extraction. The position (up to but not including) where to stop the extraction.
  • Technical details
  • More examples

:brown_circle: What are different ways to create a string object in Java?

  • Assignment of a string value encapsulated in a variable of type string.
  • - Create an object of the String class with the new keyword and pass the value of the string as a parameter to its constructor.
  • − Pass a string of characters to the String constructor.

:eight_spoked_asterisk: What is string r programming

R Strings Any value encoded by a pair of single ( ) and double ( ) quotes in R programming is called a string. In it, R stores all strings in double quotes, even if you use single quotes to construct them.

:eight_spoked_asterisk: What are strings in R?

Strings are basically a collection of character variables. This is a one-dimensional string of characters. One or more characters between a pair of matching single or double quotes can be considered a string in R. Strings are text content and can contain numbers, spaces, and special characters.

What is string manipulation in R?

What is string manipulation in R? General programming in an OpenCL program is limited to using a string processing engine, in which the program is created as a string at runtime. It is then passed to the OpenCL driver, which eventually compiles and compiles the kernel at runtime.

Can a single quote be a string in R?

Any value enclosed in single or double quotes in R is treated as a string. Internally, R stores any string in double quotes, even if you construct it in single quotes. String construction rules Quotation marks at the beginning and end of a string must be single or double.

What is an empty string in R?

Strings are basically a collection of character variables. This is a one-dimensional string of characters. One or more characters between a pair of matching single or double quotes can be considered a string in R. Strings are text content and can contain numbers, spaces, and special characters. An empty string is represented by "".

How to calculate ratio

:brown_circle: What is string r in python

The prefix r in strings means "raw strings". Standard strings use a backslash instead of escape characters: "n" is a newline, not a backslash.

:eight_spoked_asterisk: What does the are mean in Python?

In Python, r^$ is a regular expression that matches an empty string. This is similar to the regular expression (regex) commonly used in Django URL configurations. The leading r tells Python that the expression is a raw string. Escape strings are not parsed into a raw string. For example, \ is a single character for a newline.

How do I create a string in Python?

Python strings are sequences of Unicode characters. A sign is just a symbol. To create a string, use characters enclosed in single quotes ("") or double quotes ("").

:diamond_shape_with_a_dot_inside: How do you convert a number to a string in Python?


Step 1 Start the Python editor. Enter "st (number)". Press the Enter key. "Performs a string function to convert an integer to a string. The following example prompts the user for a number. Use the int function to convert a number to an integer." = record number = int (response) addFive = number +5.

Chain of command

How do I find the length of a string in Python?

To calculate the length of a string in Python 3, you need to use a function called the len function. For example: l=len(s1) # The length function is used to calculate the length of a string. The printed result returns 12, the length of the string stored by the user in a variable called s1.

:eight_spoked_asterisk: What is string r in html

Definition and Usage The metacharacter r is used to match a carriage return character. r returns the position where the carriage return character was found.

:eight_spoked_asterisk: What is string r in c

The stringr package provides a consistent set of functions to make working with strings as easy as possible. If you are unfamiliar with strings, it is best to start with the chapter on strings in R for data science.

What do the symbols n and R mean in a string?

These are common characters like a, or others. Only (invisible) entries in the chain. r moves the cursor to the beginning of the line. n goes down one line. As for his replacement, he did not say what language he was using. Here's a sketch: (rn, n) .replace(r, n).

Time series

How does the htmlstring function work?

Basically it finds all instances of the template in htmlString, replaces them with an empty string and returns the result. You need to look for pattern matching regular expressions.

:eight_spoked_asterisk: How do I find the carriage return character of a string?

The metacharacter is used to match a carriage return character. returns the position where the carriage return character was found. If no match is found, 1 is returned.

What is raw string in C++ with example?

As of C++11, you can use raw strings where escape characters (such as nt or ) are not parsed. The raw string syntax is that the literal value starts with R"( and ends with )". Let's take an example to see a raw string in C++: // A C++ program to demonstrate how a raw string works.

What is an array of strings in C?

Strings in C. Strings are defined as a sequence of characters. The difference between an array of characters and a string is that the string ends with the special character "0".

:diamond_shape_with_a_dot_inside: What is string r in excel

R (carriage return) -> move the cursor to the beginning of the line without going to the next line n (line break) -> move the cursor to the next line without returning to the beginning of the line - In the neighborhood * nothing n goes to the beginning of the line. rn (end of line) -> combination of r and n.

:eight_spoked_asterisk: What is a string in Excel?

A string, also known as a string or simply text, is a group of characters used as data in a spreadsheet. Although strings are usually words, they can also contain characters such as: Letters. numbers. Special characters such as period (.), hyphen ( ), or hash ( # ).

How do I read Excel data from a file in R?

Reading from an Excel file The R and functions can be used to read the contents of an Excel spreadsheet into an R file. The difference between the two functions is that the data type is preserved.

:diamond_shape_with_a_dot_inside: How do you extract characters from a string in R?

RIGHT function The RIGHT function returns consecutive characters from a string starting at the right (back). Simply put, the RIGHT function allows you to extract characters from the string on the left. Text: The text or number from which you want to extract characters.

Off-Chain Transactions (Cryptocurrency)

What is xlsx in R?

The Xlsx package is one of the powerful R packages for reading, writing and formatting Excel files. It is a Java based solution available for Windows, Mac and Linux. Works with Excel 2007 and Excel 97/2000/XP/2003 file formats (xls and xlsx file formats). Unfortunately the xlsx package is not very well documented.

:brown_circle: What is string r in c++

In short, a raw string literal is a string in which C++ escape characters (such as or ) are not parsed. A raw literal string starting with R (and ending with ) introduced in C++11.

What is difference between string and string in C#?

In C#, string is an alias for the String class in the .NET Framework. In fact, every C# type has a .NET equivalent. As another example, short and int in C# correspond to Int16 and Int32 in .NET. So there is technically no difference between string and string, but it is common to declare a variable using C# keywords.

How to create a string in C?

The general syntax to declare a variable as a string in C is: char string_variable_name The classical string declaration can be done like this: char string_name = string The size of the array must be defined when declaring the C-String variable as it is used to calculate the numeric characters to store in the string variable C. Here are some valid examples of string declarations:.

How do you make a string in C?

In C, strings are stored in an array of characters with a terminating null \ 0 character. In other words, to create a string in C, you create a string of characters and set each element of the string to the character value that makes up the string.

What is string literal in C?

The latest version of this section is available for C string literals. A string literal is a string from the original character set, enclosed in quotation marks . String literals are used to represent a sequence of characters that make up a zero-terminating string.

:diamond_shape_with_a_dot_inside: What is string r in r

The r at the beginning of a string literal indicates a raw string literal. It's not an operator, it's a prefix. In a normal string literal, you must escape certain characters to make them part of the string, for example: Federation.

How does concatenation operator work on list in Python?

The concatenation operator creates a new list in Python using the original lists in the order they were added. This is not an easy process. This gives the result: there are other ways to combine 2 lists. The easiest way to use the expand function is when you want to expand an existing list.

:brown_circle: What is a concatenation in Python?

Python has several ways of concatenating or concatenating strings. The newly created string is called a String object. This is obvious because everything in Python is an object, which is why Python is an object-oriented language.

What is array in C programming language?

In the C programming language, an array is a collection of values ​​of a particular data type. Arrays can be created from any C data type, such as int, float, and char. Arrays can only contain data of the specified type: for example, an integer array can contain only integer values.

:brown_circle: What is string C programming?

In C++ / C programming. A string is a set of characters treated as a whole. The string can contain letters, numbers, and various special characters. In C, string constants / string literals are enclosed in double quotes, for example:.

:brown_circle: What is concatenation in programming language

In formal language theory and computer programming, string concatenation is the operation of joining strings together from beginning to end. For example, the combination of the words "snow" and "ball" is a snowball. In some formalizations of concatenation theory, also called string theory, string concatenation is a primitive concept.

Python comment block

What is concatenation in programming styles

Concatenation is the act of concatenating multiple strings to create a new one, concatenating the strings as needed. In C#, the concatenation operator is the + sign. The + operator concatenates two string operands (left and right) into a new string.

What is string concatenation in C++?

The string concatenation operator creates a new string by appending the second operand to the end of the first operand. The string concatenation operator can concatenate not only strings, but also primitive values.

What is concatenative programming?

Concatenation programming replaces the use of functions common in other styles of programming with function composition as the standard method for creating subroutines. A sequence of operations in an application language such as the following: For example, in a concatenated language, a sequence of functions with no parameters is written:.

How to concatenate two strings in Java?

The string concatenation operator creates a new string by appending the second operand to the end of the first operand. The string concatenation operator can concatenate not only strings, but also primitive values.

Series 63

How do you concatenate a string in teststringconcatenation?

In Java, string concatenation is implemented by the StringBuilder (or StringBuffer) class and its Append method. The string concatenation operator creates a new string by appending the second operand to the end of the first operand.

What is concatenation in programming design

String Operators (Concatenation) It is often necessary to concatenate strings in a program to create a new text string. This is called concatenation.

What is concatenation in programming definition

Concatenation, concatenation, or concatenation is a term that describes the concatenation of a sequence of characters, text, or other data in a sequence without spaces. In programming languages, a function such as strcat (sequence concatenation in C) or an operator is used to indicate concatenation.

:brown_circle: Concatenate string in r form

Use the paste function to concatenate strings in r programming. The syntax of an insertion function used to concatenate two or more strings. paste (, sep =, Collar = NULL) true When concatenating strings in R, you can choose the separator and the number of input strings.

Series 65

:diamond_shape_with_a_dot_inside: How to concatenate strings?

  • Select the cell where you want to enter the formula.
  • Enter = CONCATENATE (in this cell or in the formula bar.
  • Hold down the Ctrl key and click each cell you want to merge.
  • Release the Ctrl key, type the closing parenthesis in the formula bar and press Enter.

:brown_circle: Concatenate string in r software

Use the paste function to concatenate strings in r programming. The syntax of an insertion function used to concatenate two or more strings.

What is the correlation function in R?

Pearson's correlation (r), which measures the linear relationship between two variables (x and y). It is also known as a parametric correlation test because it depends on the distribution of the data. Can only be used if x and y come from a normal distribution. The graph y = f(x) is called a linear regression curve.

Can you concatenate within a formula?

Now press F9 in the formula bar to replace the formula with the calculated values. Now type =CONCATENATE for the cell references in the formula bar, put an opening and closing parenthesis and press Enter. The CONCATENATE function returns the result as a string. The function converts numbers to text when connected.

Series 6

Can I concatenate name?

Use the JOIN function or the ampersand operator (&) to combine first and last names. Important: In Excel 2016, Excel Mobile, and Excel for the web, this function has been replaced by the CONCAT function. While the CONCATENATE function is still available for backwards compatibility, you should use CONCAT from now on.

:brown_circle: What is the abbreviation for concatenate?

How do you shorten the concatenation? CAT stands for association. CAT is very often defined as a concatenation.

Concatenate string in r pdf

You can merge them with the insert function of R. Example > insert (I, Love, R, sep=) I Love R If you want to specify characters between words, you can do so with a collapsing argument like this -> xx I love R > insert (x, contract =) ILoveR.

How to concatenate strings in R?

In this lesson you will learn how to join strings in the R programming language. Use the insert function to join strings in r programming. Insert function syntax used to combine two or more strings.. entry lines separated by commas. You can specify any number of rules.

Combine columns in excel

How to concatenate more than two strings in JavaScript?

The paste function allows you to create a concatenation with different types of separators, such as spaces or special characters. You can concatenate more than two strings with the paste function.

:brown_circle: What is R-concatenate strings?

A - Insert concatenated lines is the keyword. input lines separated by commas. Every sep share is a signal adding up.

Concatenate string in r example

Use the insert function to concatenate strings in r programming. Insert function syntax used to combine two or more strings.. entry lines separated by commas. You can specify any number of rules.

:brown_circle: How to concatenate two strings in C?

As you know, the best way to join two strings in C programming is with the strcat function. However, in this example, you're manually concatenating the two strings. Here the two strings s1 and s2 are concatenated and the result is stored in s1.

Time Series Analysis

:diamond_shape_with_a_dot_inside: What is a string operator?

String Operators (Transact-SQL) SQL Server provides the following string operators. String concatenation operators can concatenate two or more strings or binary strings, columns, or a combination of strings and column names into a single expression.

concatenate string in r