In stephlocke/Rtraining: Training Materials on R

library(foreach)

Basic operators

Action | Operator | Example ------------- | ------------- | ------------- Subtract | - | 5 - 4 = r 5 - 4 Add | + | 5 + 4 = r 5 + 4 Multiply | * | 5 * 4 = r 5 * 4 Divide | / | 5 / 4 = r 5 / 4 Raise to the power | ^ | 5 ^ 4 = r 5 ^ 4 Modulus | %% | 10 %% 4 = r 10 %% 4 Absolute remainder | %/% | 9 %/% 4 = r 9 %/% 4 Basic sequence | : | sum(1:3) = r sum(1:3)

Comparison operators

Action | Operator | Example ------------- | ------------- | ------------- Less than | < | 5 < 5 = r 5 < 5 Less than or equal to | <= | 5 <= 5 = r 5 <= 5 Greater than | > | 5 > 5 = r 5 > 5 Greater than or equal to | >= | 5 >= 5 = r 5 >= 5 Exactly equal | == | (0.5 - 0.3) == (0.3 - 0.1) is r (0.5 - 0.3) == (0.3 - 0.1), 2 == 2 is r 2==2 Not equal | != | (0.5 - 0.3) != (0.3 - 0.1) is r (0.5 - 0.3) != (0.3 - 0.1), 2 != 2 is r 2!=2 Equal | all.equal() | all.equal(0.5 - 0.3,0.3 - 0.1) is r all.equal(0.5 - 0.3,0.3 - 0.1)

States

States | Representation
------------- | ------------- True | TRUE 1 False | FALSE 0 Empty | NULL Unknown | NA Not a number e.g. 0/0| NaN Infinite e.g. 1/0 | Inf

Logical operators

Action | Operator | Example ------------- | ------------- | ------------- Not | ! | !TRUE is r !TRUE And | & | TRUE & FALSE is r TRUE & FALSE, c(TRUE,TRUE) & c(FALSE,TRUE) is r c(TRUE,TRUE) & c(FALSE,TRUE) Or | | | TRUE | FALSE is r TRUE | FALSE, c(TRUE,FALSE) | c(FALSE,FALSE) is r c(TRUE,FALSE) | c(FALSE,FALSE) Xor | xor() | xor(TRUE,FALSE) is r xor(TRUE,FALSE) Bitwise And | && | c(TRUE,TRUE) && c(FALSE,TRUE) is r c(TRUE,TRUE) && c(FALSE,TRUE) Bitwise Or | || | c(TRUE,FALSE) || c(FALSE,FALSE) is r c(TRUE,FALSE) || c(FALSE,FALSE) In | %in% | "Red" %in% c("Blue","Red") is r "Red" %in% c("Blue","Red") Not in | !( x %in% y) or Hmisc::%nin% | "Red" %nin% c("Blue","Red") = r !("Red" %in% c("Blue","Red"))

Control constructs

Type | Implementation | Example ------------- | ------------- | ------------- If | if(condition) {dosomething} | if(TRUE) { 2 } is r if(TRUE) { 2 } If else | if(condition) {do something} else {do something different} or ifelse(condition, do something, do something else) | if(FALSE) { 2 } else { 3 } is r if(FALSE) { 2 } else { 3 } ifelse(FALSE, 2, 3) is r ifelse(FALSE, 2, 3) For loop | for(i in seq) {dosomething} or foreach::foreach(i=1:3) %do% {something} | foreach(i=1:3) %do% {TRUE} is r rep(TRUE,3) While loop | while(condition) {do something } | a<-0 ; while(a<3){a<-a+1} ; a is r a<-0 ; while(a<3){a<-a+1} ; a Switch | switch(value, ...) | switch(2, "a", "b") is r switch(2, "a", "b") Case | memisc::cases(...) | cases("pi<3"=pi<3, "pi=3"=pi==3,"pi>3"=pi>3) is r memisc::cases("pi<3"=pi<3, "pi=3"=pi==3,"pi>3"=pi>3)

NB: If you find yourself using a loop, there's probably a better, faster solution

Assignment operators

Action | Operator | Example ------------- | ------------- | ------------- Create / update a variable | <- | a <- 10

NB: There are others you could use, but this is the best practice

Accessors

Action | Operator | Example ------------- | ------------- | ------------- Use public function from package | :: | memisc::cases() Use private function from package | ::: | optiRum:::pounds_format() Get a component e.g a data.frame column | $ | iris$Sepal.Length Extract a property from a class | @ | Won't be used in this course Refer to positions in a data.frame or vector | [ ] | iris[5:10,1] Refer to item in a list | [[ ]] | list(iris=iris,mtcars=mtcars)[["iris"]]

Meta-operators

Action | Operator | Example ------------- | ------------- | ------------- Comment | # | # This is my comment Help | ? | ?data.table Identifier | ` | `r 'irisDT[ , \x60:=\x60(CreatedDate = Sys.Date())]'`

stephlocke/Rtraining documentation built on May 30, 2019, 3:36 p.m.