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Type the string "Arr, matey!". (Don't forget the quotes!)
> "Arrm matey!" [1] "Arrm matey!"
Now try multiplying 6 times 7 (* is the multiplication operator).
6 * 7
As in other programming languages, you can store values into a variable to access it later. Type x <- 42 to store a value in x.
代入は x <- 42 または x = 42 のように書きます。
x can now be used in expressions in place of the original result. Try dividing x by 2 (/ is the division operator).
> x/2 [1] 21
合計は SUM を使います。
> sum(1, 3, 5) [1] 9
次のデータは8匹のペットハムスターの体長です。
7.6, 8.2, 9.6, 7.1, 10.3, 8.5, 9.3, 10.6
この体長の合計を求めなさい。（室淳子，石村貞夫『平均・分散・標準偏差』東京図書，p4）
7.6 + 8.2 + 9.6 + 7.1 + 10.3 + 8.5 + 9.3 + 10.6で求めることができます。しかし，ここでは体長という変数を用意し，SUM関数で処理してみましょう。
> 体長 = c(7.6, 8.2, 9.6, 7.1, 10.3, 8.5, 9.3, 10.6) > sum(体長) [1] 71.2
したがって，8匹のペットハムスターの体長の合計は 71.2 cm です。
> 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(functionname) brings up help for the given function. Try displaying help for the sum function:
> help(sum)
sum package:base R Documentation
Sum of Vector Elements
Description:
'sum' returns the sum of all the values present in its arguments.
Usage:
sum(..., na.rm = FALSE)
...
example(functionname) brings up examples of usage for the given 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 ...
We've stored a couple sample scripts for you. You can list the files in the current directory from within R, by calling the list.files function. Try it now:
> list.files() [1] "bottle1.R" "bottle2.R"
To run a script, pass a string with its name to the source function. Try running the "bottle1.R" script:
> source("bottle1.R")
[1] "This be a message in a bottle1.R!"
A vector's values can be numbers, strings, logical values, or any other type, as long as they're all the same type. Try creating a vector of numbers, like this:
> c(4,7,9) [1] 4 7 9
The c function (c is short for Combine) creates a new vector by combining a list of values.
Now try creating a vector with strings:
> c('a','b','c')
[1] "a" "b" "c"
Vectors cannot hold values with different modes (types). Try mixing modes and see what happens:
> c(1,TRUE,"three") [1] "1" "TRUE" "three"
All the values were converted to a single mode (characters) so that the vector can hold them all.
If you need a vector with a sequence of numbers you can create it with start:end notation. Let's make a vector with values from 5 through 9:
> 5:9 [1] 5 6 7 8 9
A more versatile way to make sequences is to call the seq function. Let's do the same thing with seq:
> seq(5,9) [1] 5 6 7 8 9
seq also allows you to use increments other than 1. Try it with steps of 0.5:
> seq(5,9,0.5) [1] 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
Now try making a vector with integers from 9 down to 5:
> 9:5 [1] 9 8 7 6 5
The barplot function draws a bar chart with a vector's values. We'll make a new vector for you, and store it in the vesselsSunk variable.
Now try passing the vector to the barplot function:
> vesselsSunk <- c(4, 5, 1) > barplot(vesselsSunk)
If you assign names to the vector's values, R will use those names as labels on the bar plot. Let's use the names assignment function again:
> names(vesselsSunk) <- c("England", "France", "Norway")
Now, if you call barplot with the vector again, you'll see the labels:
> barplot(vesselsSunk)
Now, try calling barplot on a vector of integers ranging from 1 through 100:
> barplot(1:100)
リンクはご自由にどうぞ。
Last modified: 2016-11-12 14:23:08