r lang初步学习记录(1)

num <- 10
class(num)
# [1] "numeric"
int <- 10L
class(int)
# [1] "integer"
string <- "My first R code"
class(string)
# [1] "character"
complex <- 3+2i
class(complex)
# [1] "complex"
boolean <- TRUE
class(boolean)
# [1] "logical"


# 创建向量vector
x <- vector("numeric", length=4)
# 创建向量vector 方法1
x1 <- 1:4
# 创建向量vector 方法2
x2 <- c(1L,2L,3L,4L)
# 创建向量vector 方法3
x3 <- c("a", "b", "c", "d")

#矩阵类型统一
c = matrix(c("a", 1L, "b", TRUE), nrow = 2, ncol = 2)
# Output
#      [,1] [,2]  
# [1,] "a"  "b"   
# [2,] "1"  "TRUE"
c1 = matrix(c(1, 1L, 2L, TRUE), nrow = 2, ncol = 2)
c1
# Output
#         [,1] [,2]
# [1,]    1    2
# [2,]    1    1

c1 = matrix(c(1, TRUE, 2.5, 3.2, TRUE, 20L, 5.0, 6, 7), nrow = 3, ncol = 3)
c1
# Output
#       [,1] [,2]  [,3]
# [1,]  1.0  3.2   5
# [2,]  1.0  1.0   6
# [3,]  2.5  20.0  7
# 按列转化: 整数(非L)有精度的会 同一列变成浮点数
# 转化优先级: 实数 > 浮点数 > 整数(L) > 字符串 > Logical

class(x)
#[1] "numeric"
class(x1)
#[1] "integer"
class(x2)
#[1] "integer"
class(x3)
#[1] "character"

m <- matrix(1:256, nrow=16, ncol=16)
# 创建16 x 16的矩阵

class(x1)
names(x1) <- c("a", "b", "c", "d")

x <- matrix(1:6, nrow = 2, ncol = 3)
dim(x)
attributes(x)

y <- 6:1
dim(y) <- c(2,3)
cbind(x, y)

x5 <- array(1:24, c(4,6))
x5

l <- list("a", 2, 10L, TRUE, 3+5i)
l2 <- list(a=1, b=2, c=3)
names(l2)

# l <- list("a", 2, 10L, 3+4i, TRUE)
# l2 <- list(a=1, b=2, c=3)
# l3 <- list(c(1,2,3), c(4,5,6,7))
# x <- matrix(1:6, nrow = 2, ncol = 3)
# dimnames(x) <- list(c("a", "b"), c("c", "d", "e"))
x <- character(26)

a = NaN
b=  NA

a1 <- c(1, NA, 2, NA, 3)
is.na(a)
is.nan(a)
# b

df <- data.frame(id = c(1,2,3,4), name = c("Mot","Michael","Sunny", "Yu"), gender = c(TRUE, TRUE, FALSE, TRUE))
df
data.matrix(df)

now <- date()
# class(now) : character
now2 <- Sys.Date()
# class(now2) : Date
now3 <- as.Date("2014-11-30")
#class(now3) : Date

weekdays(now3)
# Output:
# 星期四
quarters(now3)
# Output:
# Q4
julian(now3)
# Output:
# [1] 16404
# attr(,"origin")
# [1] "1970-01-01"
now2 - now3
# Output:
# Time difference of 1096 days