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Expressions

1.1 Type anything in the dialog box and R will calculate it and output the answer. Let’s try some simple math. Type the following command.

1 + 1 
## [1] 2

[1] 2 Here is your result, 2. It is printed on the console immediately after your entry.

1.1 Type the string “Arr, matey!” (Don’t forget the quotation marks!).

"Arr, matey!"
## [1] "Arr, matey!"

Now try multiplying 6 times 7 (* is the multiplication operator).

6 * 7
## [1] 42

Boolean values

1.2 Some expressions return a “Boolean value”: TRUE or FALSE. (Many programming languages refer to these as “boolean” values.) Let’s try typing an expression that gives us a Boolean value:

3 < 4
## [1] TRUE

And another Boolean value (note that you need a double equal sign to check if two values are equal - a single equal sign will not work):

2 + 2 == 5
## [1] FALSE

T and F are abbreviations for TRUE and FALSE. Try this:

T == TRUE
## [1] TRUE

Variables

1.3 As in other programming languages, you can store values in a variable to access them later. Type x <- 42 to store a value in x.

x <- 42

x can now be used in expressions in place of the original result. Try dividing x by 2 (/ is the divide operator).

x / 2
## [1] 21

You can reassign any value to a variable at any time. Try assigning “Arr, matey!” to x.

x <- "Arr, matey!"

You can print the value of a variable at any time by simply typing its name in the console. Try printing the current value of x.

x
## [1] "Arr, matey!"

Now try assigning the logical value TRUE to x.

x <- TRUE

Functions

1.4 You call a function by typing its name followed by one or more arguments in parentheses. Let’s try using the sum function to add up several numbers. Enter:

sum(1, 3, 5)
## [1] 9

Some arguments have names. For example, to repeat a value 3 times, you would call the rep function and give it the times argument:

rep("Yo ho!", times = 3)
## [1] "Yo ho!" "Yo ho!" "Yo ho!"

Try calling the sqrt function to get the square root of 16.

sqrt(16)
## [1] 4

Help

help(functionname) displays help for the specified function. Try displaying help for the sum function:

help(sum)
## starting httpd help server ... done

suma pakiet:base Dokumentacja R

Suma elementów wektora

Opis:

 'sum' zwraca sumę wszystkich wartości występujących w jej argumentach.

Użycie:

 sum(..., na.rm = FALSE)

… (Don’t worry about that optional argument to.rm, we’ll deal with that later). example(functionname) displays examples of how to use the specified function. Try displaying examples for the min function:

example(min)
## 
## min> require(stats); require(graphics)
## 
## min>  min(5:1, pi) #-> one number
## [1] 1
## 
## min> pmin(5:1, pi) #->  5  numbers
## [1] 3.141593 3.141593 3.000000 2.000000 1.000000
## 
## min> x <- sort(rnorm(100));  cH <- 1.35
## 
## min> pmin(cH, quantile(x)) # no names
## [1] -2.18085241 -0.71792818  0.01370801  0.67766938  1.35000000
## 
## min> pmin(quantile(x), cH) # has names
##          0%         25%         50%         75%        100% 
## -2.18085241 -0.71792818  0.01370801  0.67766938  1.35000000 
## 
## min> plot(x, pmin(cH, pmax(-cH, x)), type = "b", main =  "Huber's function")

## 
## min> cut01 <- function(x) pmax(pmin(x, 1), 0)
## 
## min> curve(      x^2 - 1/4, -1.4, 1.5, col = 2)

## 
## min> curve(cut01(x^2 - 1/4), col = "blue", add = TRUE, n = 500)
## 
## min> ## pmax(), pmin() preserve attributes of *first* argument
## min> D <- diag(x = (3:1)/4) ; n0 <- numeric()
## 
## min> stopifnot(identical(D,  cut01(D) ),
## min+           identical(n0, cut01(n0)),
## min+           identical(n0, cut01(NULL)),
## min+           identical(n0, pmax(3:1, n0, 2)),
## min+           identical(n0, pmax(n0, 4)))

Now try calling help for the rep function:

help(rep) rep package:base R documentation

Replicate Elements of Vectors and Lists

Description:

 'rep' replicates the values in 'x'. This is a generic function, and the
 (internal) default method is described here.

…

Files

Typing commands every time you need them only works for short scripts, of course. R commands can also be saved in text files (with the “.R” extension, by convention) for execution later. They can be run directly from the command line or from a running instance of R.

Let’s make an object a<-“This is information” and then save it in the current directory under the name File1.r

a<-"To jest informacja"
save(a, file ="Plik1.r")

We can now see if File1.r exists in the current floder.

list.files()
##  [1] "Cw_1.docx"                "Cw_1.html"               
##  [3] "Cw_1.Rmd"                 "Cw_1_EN.html"            
##  [5] "Cw_1_EN.Rmd"              "Cw_1_EN_files"           
##  [7] "Cw_1n.nb.html"            "Cw_1n.Rmd"               
##  [9] "Cw_3.html"                "Cw_3.Rmd"                
## [11] "Cw_4.html"                "Cw_4.Rmd"                
## [13] "Cw_4_EN.docx"             "Cw_4_EN.html"            
## [15] "Cw_4_EN.pdf"              "Cw_4_EN.Rmd"             
## [17] "Cw_6_EN_AN.html"          "Cw_6_EN_AN.Rmd"          
## [19] "Cw_6_PL_AN.html"          "Cw_6_PL_AN.Rmd"          
## [21] "Cw_8_EN_PR_GC.html"       "Cw_8_EN_PR_GC.nb.html"   
## [23] "Cw_8_EN_PR_GC.Rmd"        "Cw_8_PL_PR_GC.html"      
## [25] "Cw_8_PL_PR_GC.Rmd"        "Cw1.Rhistory"            
## [27] "Cw2"                      "Cw2-EN-RynekBankowy.html"
## [29] "Cw2-EN-RynekBankowy.pdf"  "Cw2-EN-RynekBankowy.Rmd" 
## [31] "Cw2-RynekBankowy.html"    "Cw2-RynekBankowy.pdf"    
## [33] "Cw2 RynekBankowy.Rmd"     "Cw2_EN_RynekBankowy.html"
## [35] "Cw2_EN_RynekBankowy.pdf"  "Cw2_EN_RynekBankowy.Rmd" 
## [37] "Cw3"                      "Cw3_EN.html"             
## [39] "Cw3_EN.Rmd"               "Cw3_PL.html"             
## [41] "Cw3_PL.Rmd"               "Cw4 AuditMatieraltiy"    
## [43] "Kody pomocnicze"          "OB"                      
## [45] "path"                     "pentle.R"                
## [47] "Plik1.r"                  "Plik2.r"                 
## [49] "Plik3.r"                  "R Audit.Rproj"           
## [51] "references.bib"           "rmarkdown.pdf"           
## [53] "rsconnect"                "test.html"               
## [55] "test.Rmd"                 "Z1_A_MQT_Probkowanie.Rmd"
## [57] "Z1_MQT_Probkowanie.docx"  "Z1_MQT_Probkowanie.html" 
## [59] "Z1_MQT_Probkowanie.Rmd"

Further learning

R has a self-study system called Swirl [https://swirlstats.com/]. It is package with built-in learning courses, to use it you need to:

First, install the swirl package:

install.packages(“swirl”) from the console.

Then run it

library(swirl)
## 
## | Hi! I see that you have some variables saved in your workspace. To keep
## | things running smoothly, I recommend you clean up before starting swirl.
## 
## | Type ls() to see a list of the variables in your workspace. Then, type
## | rm(list=ls()) to clear your workspace.
## 
## | Type swirl() when you are ready to begin.

And from the console give the swirl() command to start the learning process. Mastering this package requires 2-3 weeks of work, but it’s worth it.