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Teaching courses in programming language R

With any phrase that is enclosed in two quotation marks (” or ”); In the programming language R, it behaves like a string. In fact, R stores all the strings inside the quotation mark;

Even when you put them in single quotes (ie ”).

Rules applied in string structure

  • The mark you put at the beginning and end of the string; Both must be a double quotation mark; Or be a single quotation mark. You cannot use one character as a binary and the other as a single character.
  • A double quote can be used for a string that itself is marked with a single quotation mark.
  • A single quote can be used for a string that itself is marked with a double quotation mark.
  • Binary quotes cannot be used for a string that itself is marked with a double quotation mark.
  • A single quote cannot be used for a string that itself is marked with a single quote.

Examples of authorized strings

The following examples better illustrate the rules for creating a string in R.

a <- ‘Start and end with single quote’

print (a)

b <- “Start and end with double quotes”

print (b)

c <- “single quote ‘in between double quotes”

print (c)

d <- ‘Double quotes ”in between single quote’

print (d)

When we run the above code; The following result is obtained:

[1] “Start and end with single quote”

[1] “Start and end with double quotes”

[1] “single quote ‘in between double quote”

[1] “Double quote \” in between single quote “

Examples of unauthorized strings

e <- ‘Mixed quotes ”

print (e)

f <- ‘Single quote’ inside single quote ‘

print (f)

g <- “Double quotes” inside double quotes ”

print (g)

When we run the above script; The following results could not be provided:

Error: unexpected symbol in:

“Print (e)

f <- ‘Single ”

Execution halted

Manipulation of strings

Connecting strings – paste () function

There are many strings in R that are combined using the paste () function. Using this function, any number of arguments can be combined.

Syntax

You can see the basic syntax for the paste function below:

paste (…, sep = ”“, collapse = NULL)

  • . Indicates that any number of arguments can be combine.
  • sep represents the separator between arguments. Its placement is optional.
  • collapse is used to limit the distance between two strings. But it does not change the distance between two words in a string.

Example

When we run the above code; The following result is obtain:

[1] “Hello How are you? “

[1] “Hello-How-are you? “

[1] “HelloHoware you? “

Formatting numbers and strings – function () format in language R

Numbers and strings can be formatted in a specific style using the format () function

Syntax

The basic syntax for the format function is as follows:

format (x, digits, nsmall, scientific, width, justify = c (“left”, “right”, “center”, “none”))

The following parameters are using:

  • x is the input vector.
  • digits is the total number of digits shown.
  • nsmall is the minimum number of numbers to the right of a decimal point.
  • scientific is set to TRUE to display scientific symbols.
  • width indicates the transverse minimum using the empty padding spaces at the beginning; is shown.
  • justify is used to display strings on the left, right or middle.

Example

# Total number of digits displayed. Last digit rounded off.

result <- format (23.123456789, digits = 9)

print (result)

# Display numbers in scientific notation.

result <- format (c (6, 13.14521), scientific = TRUE)

print (result)

# The minimum number of digits to the right of the decimal point.

result <- format (23.47, nsmall = 5)

print (result)

# Format treats everything as a string.

result <- format (6)

print (result)

# Numbers are pad with blank in the beginning for width.

result <- format (13.7, width = 6)

print (result)

# Left justify strings.

result <- format (“Hello”, width = 8, justify = “l”)

print (result)

# Justfy string with center.

result <- format (“Hello”, width = 8, justify = “c”)

print (result)

When we run the above code; The following result is obtained:

[1] “23.1234568”

[1] “6,000,000 e + 00” “1.314521e + 01”

[1] “23.47000”

[1] “6”

[1] “13.7”

[1] “Hello”

[1] “Hello”

Counting the number of characters in a string – ncahr () function in language R

This function is the number of characters in a string; Includes counting their distances.

Syntax

The basic syntax for the nchar () function is as follows:

nchar (x)

nchar (x)

The following are the parameters uses in this syntax:

  • x is a vector input.

Example

result <- nchar (“Count the number of characters”)

print (result)

When we execute the above code; The following result is obtain:

[1] 30

Case change – toupper () and tolower () functions

This function changes the characters of a string:

Syntax

The syntax of the toupper () and tolower () functions is as follows:

toupper (x)

tolower (x)

  • x is the vector input in the syntax above.

Example

# Changing to Upper case.

result <- toupper (“Changing To Upper”)

print (result)

# Changing to lower case.

result <- tolower (“Changing To Lower”)

print (result)

When we run the above code; The following results are obtain:

[1] “CHANGING TO UPPER”

[1] “changing to lower”

Extract parts of a string-function () substring

This function extracts parts of a string.

Syntax

The basic syntax for the substring () function is as follows:

substring (x, first, last)

The variables used in the above syntax are:

  • x is the vector input of the character.
  • first position is the first character to be extract.
  • last is the position of the last character to be extract.

Example

# Extract characters from 5th to 7th position.

result <- substring (“Extract”, 5, 7)

print (result)

When we run the above code; The following result is obtain:

[1] “act”

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