R语言-数据结构

主站：https://lartpang.github.io/

之前一阵子，在EDX上学习了R语言的一门基础课程，这里做个总结。这门课程主要侧重于R的数据结构的介绍，当然也介绍了它的基本的绘图手段。

工作空间相关

ls()

## character(0)

rm(a)

## Warning in rm(a): 找不到对象'a'

ls()

## character(0)

基本数据类型

logical
- TRUE/FALSE/NA/T/F(推荐使用完整形式)/某些时候的0与非0
numeric
- integer is numeric
- numeric not always integer
character

Other atomic types:

double: higher precision
complex: complex numbers
raw: store raw bytes

is.*()返回括号内内容是否是*对应类型。

# logical
TRUE

## [1] TRUE

class(TRUE)

## [1] "logical"

FALSE

## [1] FALSE

class(NA)

## [1] "logical"

T

## [1] TRUE

F

## [1] FALSE

# numeric
2

## [1] 2

class(2)

## [1] "numeric"

2.5

## [1] 2.5

class(2.5)

## [1] "numeric"

2L

## [1] 2

class(2L) 

## [1] "integer"

is.numeric(2)

## [1] TRUE

is.numeric(2L)

## [1] TRUE

#integer is numeric 
#numeric not always integer
is.integer(2)

## [1] FALSE

is.integer(2L)

## [1] TRUE

# character
 "I love data science!"

## [1] "I love data science!"

 class("I love data science!")

## [1] "character"

强制转换

as.*()返回括号内内容转化为*对应类型后的结果，有些情况无法转换。

as.numeric(TRUE)

## [1] 1

as.numeric(FALSE)

## [1] 0

as.character(4)

## [1] "4"

as.numeric("4.5")

## [1] 4.5

as.integer("4.5")

## [1] 4

as.numeric("Hello")

## Warning: 强制改变过程中产生了NA

## [1] NA

向量 Vector

Sequence of data elements
Same basic type
- Automatic coercion if necessary
character, numeric, logical
Single value = Vector

创建 `c()`或者利用`:`

# c()
drawn_suits <- c("hearts", "spades", "diamonds",  
                   "diamonds", "spades")
drawn_suits

## [1] "hearts"   "spades"   "diamonds" "diamonds" "spades"

is.vector(drawn_suits)

## [1] TRUE

# :
1:5

## [1] 1 2 3 4 5

is.vector(1:5)

## [1] TRUE

命名 `names()`

remain <- c(11, 12, 11, 13)
suits <- c("spades", "hearts", "diamonds", "clubs")
names(remain) <- suits
remain 

##   spades   hearts diamonds    clubs 
##       11       12       11       13

#or
remain <- c(spades = 11, hearts = 12,  
              diamonds = 11, clubs = 13)
remain

##   spades   hearts diamonds    clubs 
##       11       12       11       13

#or
remain <- c("spades" = 11, "hearts" = 12,  
              "diamonds" = 11, "clubs" = 13)
remain

##   spades   hearts diamonds    clubs 
##       11       12       11       13

单值仍为向量

my_apples <- 5 
my_oranges <- "six" 
is.vector(my_apples)

## [1] TRUE

is.vector(my_oranges)

## [1] TRUE

length(my_apples)

## [1] 1

length(my_oranges)

## [1] 1

强制变换

drawn_ranks <- c(7, 4, "A", 10, "K", 3, 2, "Q")
drawn_ranks

## [1] "7"  "4"  "A"  "10" "K"  "3"  "2"  "Q"

class(drawn_ranks)

## [1] "character"

基本运算

很自然的可以由单数的运算推广出来。

# with number: +-*/
earnings <- c(50, 100, 30)
earnings * 3

## [1] 150 300  90

earnings^2

## [1]  2500 10000   900

# with vector: +-*/
earnings <- c(50, 100, 30) 
expenses <- c(30, 40, 80) 
bank <- earnings - expenses
## sum() >
sum(bank)

## [1] 30

earnings > expenses

## [1]  TRUE  TRUE FALSE

## multiplication and division are done element-wise!
earnings * c(1, 2, 3)

## [1]  50 200  90

子集

三种索引方式

序号（R从1开始）
名字 —— names()的利用
逻辑值

remain <- c(spades = 11, hearts = 12,  
              diamonds = 11, clubs = 13)
remain[1]

## spades 
##     11

remain["spades"]

## spades 
##     11

remain[c(4, 1)] # 此法可以用来交换或者抽取特定位置的元素

##  clubs spades 
##     13     11

remain[c("clubs", "spades")]

##  clubs spades 
##     13     11

# 逻辑值索引，短的会被自动循环使用
remain[c(TRUE, FALSE)]

##   spades diamonds 
##       11       11

remain[c(TRUE, FALSE, TRUE, FALSE)]

##   spades diamonds 
##       11       11

# 负索引，“all but it”，返回除此之外的元素
remain[-1]

##   hearts diamonds    clubs 
##       12       11       13

remain[-c(1, 2)]

## diamonds    clubs 
##       11       13

#remain[-"spades"] #can't work

矩阵 Matrix

Vector: 1D array of data elements
Matrix: 2D array of data elements
Rows and columns
One atomic vector type

创建 `matrix()`

默认按列填充

# 直接创建
matrix(1:6, nrow = 2)

##      [,1] [,2] [,3]
## [1,]    1    3    5
## [2,]    2    4    6

matrix(1:6, ncol = 3)

##      [,1] [,2] [,3]
## [1,]    1    3    5
## [2,]    2    4    6

matrix(1:6, nrow = 2, byrow = TRUE)

##      [,1] [,2] [,3]
## [1,]    1    2    3
## [2,]    4    5    6

# 循环创建
matrix(1:3, nrow = 2, ncol = 3)

##      [,1] [,2] [,3]
## [1,]    1    3    2
## [2,]    2    1    3

matrix(1:4, nrow = 2, ncol = 3)

## Warning in matrix(1:4, nrow = 2, ncol = 3): 数据长度[4]不是矩阵列数[3]的整
## 倍数

##      [,1] [,2] [,3]
## [1,]    1    3    1
## [2,]    2    4    2

# 组合创建
cbind(1:3, 1:3)

##      [,1] [,2]
## [1,]    1    1
## [2,]    2    2
## [3,]    3    3

rbind(1:3, 1:3)

##      [,1] [,2] [,3]
## [1,]    1    2    3
## [2,]    1    2    3

m <- matrix(1:6, byrow = TRUE, nrow = 2)
rbind(m, 7:9)

##      [,1] [,2] [,3]
## [1,]    1    2    3
## [2,]    4    5    6
## [3,]    7    8    9

cbind(m, c(10, 11))

##      [,1] [,2] [,3] [,4]
## [1,]    1    2    3   10
## [2,]    4    5    6   11

命名

rownames(), colnames()

m <- matrix(1:6, byrow = TRUE, nrow = 2)
rownames(m) <- c("row1", "row2")
m

##      [,1] [,2] [,3]
## row1    1    2    3
## row2    4    5    6

colnames(m) <- c("col1", "col2", "col3")
m

##      col1 col2 col3
## row1    1    2    3
## row2    4    5    6

# 直接命名
m <- matrix(1:6, byrow = TRUE, nrow = 2,  
              dimnames = list(c("row1", "row2"),  
                              c("col1", "col2", "col3"))) 
m

##      col1 col2 col3
## row1    1    2    3
## row2    4    5    6

强制转换

num <- matrix(1:8, ncol = 2)
num

##      [,1] [,2]
## [1,]    1    5
## [2,]    2    6
## [3,]    3    7
## [4,]    4    8

char <- matrix(LETTERS[1:6], nrow = 4, ncol = 3)
char

##      [,1] [,2] [,3]
## [1,] "A"  "E"  "C" 
## [2,] "B"  "F"  "D" 
## [3,] "C"  "A"  "E" 
## [4,] "D"  "B"  "F"

num <- matrix(1:8, ncol = 2)
char <- matrix(LETTERS[1:6], nrow = 4, ncol = 3)
cbind(num, char)

##      [,1] [,2] [,3] [,4] [,5]
## [1,] "1"  "5"  "A"  "E"  "C" 
## [2,] "2"  "6"  "B"  "F"  "D" 
## [3,] "3"  "7"  "C"  "A"  "E" 
## [4,] "4"  "8"  "D"  "B"  "F"

子集运算

m <- matrix(sample(1:15, 12), nrow = 3)
rownames(m) <- c("r1", "r2", "r3") 
colnames(m) <- c("a", "b", "c", "d")
m

##     a  b  c  d
## r1  7  5  6 10
## r2  3  9 12  8
## r3 15 13  2  4

m[1,3]

## [1] 6

m[3,] 

##  a  b  c  d 
## 15 13  2  4

m[,3]

## r1 r2 r3 
##  6 12  2

m[4] # 默认按列计数 

## [1] 5

m[2, c(2, 3)]

##  b  c 
##  9 12

m[c(1, 2), c(2, 3)]

##    b  c
## r1 5  6
## r2 9 12

m[c(1, 3), c(1, 3, 4)]

##     a c  d
## r1  7 6 10
## r3 15 2  4

m["r2","c"]

## [1] 12

m[2,"c"]

## [1] 12

m[3, c("c", "d")]

## c d 
## 2 4

m[c(FALSE, FALSE, TRUE),  
    c(FALSE, TRUE, FALSE, TRUE)] 

##  b  d 
## 13  4

m[c(FALSE, FALSE, TRUE),  
    c(FALSE, TRUE)]

##  b  d 
## 13  4

矩阵运算

colSums(), rowSums()
Standard arithmetic possible
Element-wise computation

the_fellowship <- c(316, 556) 
two_towers <- c(343, 584) 
return_king <- c(378, 742) 
lotr_matrix <- rbind(the_fellowship, two_towers, return_king) 
colnames(lotr_matrix) <- c("US", "non-US") 
rownames(lotr_matrix) <- c("Fellowship", "Two Towers",  
                             "Return King") 
lotr_matrix

##              US non-US
## Fellowship  316    556
## Two Towers  343    584
## Return King 378    742

# 与数字 +-*/
lotr_matrix / 1.12 

##                   US   non-US
## Fellowship  282.1429 496.4286
## Two Towers  306.2500 521.4286
## Return King 337.5000 662.5000

lotr_matrix - 50

##              US non-US
## Fellowship  266    506
## Two Towers  293    534
## Return King 328    692

# 与矩阵 +-*/ (这里不是线性代数中的矩阵计算)
theater_cut <- matrix(c(50, 80, 100), nrow = 3, ncol = 2)
theater_cut

##      [,1] [,2]
## [1,]   50   50
## [2,]   80   80
## [3,]  100  100

lotr_matrix - theater_cut

##              US non-US
## Fellowship  266    506
## Two Towers  263    504
## Return King 278    642

# 与向量
lotr_matrix - c(50, 80, 100) #按列循环计算

##              US non-US
## Fellowship  266    506
## Two Towers  263    504
## Return King 278    642

因子 Factors

Factors for categorical variables
Limited number of different values
Belong to category

创建因子 `factor()`

blood <- c("B", "AB", "O", "A", "O", "O", "A", "B")
blood

## [1] "B"  "AB" "O"  "A"  "O"  "O"  "A"  "B"

blood_factor <- factor(blood) # 默认等级按照字母顺序定
blood_factor

## [1] B  AB O  A  O  O  A  B 
## Levels: A AB B O

str(blood_factor)

##  Factor w/ 4 levels "A","AB","B","O": 3 2 4 1 4 4 1 3

# 自定义level
blood_factor2 <- factor(blood, 
                          levels = c("O", "A", "B", "AB"))
blood_factor2

## [1] B  AB O  A  O  O  A  B 
## Levels: O A B AB

str(blood_factor2)

##  Factor w/ 4 levels "O","A","B","AB": 3 4 1 2 1 1 2 3

Rename factor levels

blood <- c("B", "AB", "O", "A", "O", "O", "A", "B")
#1.1
blood_factor <- factor(blood)
levels(blood_factor) <- c("BT_A", "BT_AB", "BT_B", "BT_O")
#1.2
blood <- c("B", "AB", "O", "A", "O", "O", "A", "B") 
blood_factor <- factor(blood) 
factor(blood,  
         levels = c("O", "A", "B", "AB"),  
         labels = c("BT_O", "BT_A", "BT_B", "BT_AB"))

## [1] BT_B  BT_AB BT_O  BT_A  BT_O  BT_O  BT_A  BT_B 
## Levels: BT_O BT_A BT_B BT_AB

#2
factor(blood, labels = c("BT_A", "BT_AB", "BT_B", "BT_O"))

## [1] BT_B  BT_AB BT_O  BT_A  BT_O  BT_O  BT_A  BT_B 
## Levels: BT_A BT_AB BT_B BT_O

Ordered factor

blood <- c("B", "AB", "O", "A", "O", "O", "A", "B")
blood_factor <- factor(blood) 
blood_factor[1] < blood_factor[2] 

## Warning in Ops.factor(blood_factor[1], blood_factor[2]): '<' not meaningful
## for factors

## [1] NA

# 下面比较大小才是有意义的
tshirt <- c("M", "L", "S", "S", "L", "M", "L", "M")
tshirt_factor <- factor(tshirt, ordered = TRUE, 
                          levels = c("S", "M", "L"))
tshirt_factor

## [1] M L S S L M L M
## Levels: S < M < L

tshirt_factor[1] < tshirt_factor[2]

## [1] TRUE

列表 List

Vector - Matrix - List

Vector: 1D, same type
Matrix: 2D, same type
List:
- Different R objects
- No coercion
- Loss of some functionality

创建列表 `list()`

list("Rsome times", 190, 5)

## [[1]]
## [1] "Rsome times"
## 
## [[2]]
## [1] 190
## 
## [[3]]
## [1] 5

song <- list("Rsome times", 190, 5)
is.list(song)

## [1] TRUE

命名列表

#1
song <- list("Rsome times", 190, 5) 
names(song) <- c("title", "duration", "track")
song

## $title
## [1] "Rsome times"
## 
## $duration
## [1] 190
## 
## $track
## [1] 5

#2
song <- list(title = "Rsome times",  
               duration = 190,  
               track = 5)
song

## $title
## [1] "Rsome times"
## 
## $duration
## [1] 190
## 
## $track
## [1] 5

str(song)

## List of 3
##  $ title   : chr "Rsome times"
##  $ duration: num 190
##  $ track   : num 5

列表嵌套

similar_song <- list(title = "R you on time?", 
                       duration = 230)
song <- list(title = "Rsome times", 
               duration = 190, track = 5,  
               similar = similar_song)
str(song)

## List of 4
##  $ title   : chr "Rsome times"
##  $ duration: num 190
##  $ track   : num 5
##  $ similar :List of 2
##   ..$ title   : chr "R you on time?"
##   ..$ duration: num 230

子集运算

[ versus [[

similar_song <- list(title = "R you on time?", 
                       duration = 230) 
song <- list(title = "Rsome times", 
               duration = 190, track = 5, 
               similar = similar_song) 
str(song)

## List of 4
##  $ title   : chr "Rsome times"
##  $ duration: num 190
##  $ track   : num 5
##  $ similar :List of 2
##   ..$ title   : chr "R you on time?"
##   ..$ duration: num 230

song[1]

## $title
## [1] "Rsome times"

song[[1]]

## [1] "Rsome times"

song[c(1, 3)] 

## $title
## [1] "Rsome times"
## 
## $track
## [1] 5

#song[[c(1, 3)]] #can't work
#song[[1]][[3]] #can't work
song[["duration"]]

## [1] 190

song["duration"]

## $duration
## [1] 190

song[c(FALSE, TRUE, TRUE, FALSE)]

## $duration
## [1] 190
## 
## $track
## [1] 5

#song[[c(FALSE, TRUE, TRUE, FALSE)]] # can't work
#song[[F]][[T]][[T]][[F]] #also

# list in list
song[[4]][[1]]

## [1] "R you on time?"

song[[c(4, 1)]]

## [1] "R you on time?"

song[c("duration", "similar")] 

## $duration
## [1] 190
## 
## $similar
## $similar$title
## [1] "R you on time?"
## 
## $similar$duration
## [1] 230

[[ or [ ? + [[ to select list element + [ results in
sublist + [[ and $ to subset and extend lists

列表扩展

这里引出了R中比较重要的一个符号$

similar_song <- list(title = "R you on time?", 
                       duration = 230) 
song <- list(title = "Rsome times", 
               duration = 190, track = 5, 
               similar = similar_song) 
#$
song$duration

## [1] 190

#extending
friends <- c("Kurt", "Florence",
                "Patti", "Dave")
song$sent <- friends #或者 song[["sent"]] <- friends
song$similar$reason <- "too long"
song

## $title
## [1] "Rsome times"
## 
## $duration
## [1] 190
## 
## $track
## [1] 5
## 
## $similar
## $similar$title
## [1] "R you on time?"
## 
## $similar$duration
## [1] 230
## 
## $similar$reason
## [1] "too long"
## 
## 
## $sent
## [1] "Kurt"     "Florence" "Patti"    "Dave"

数据框 Data Frame

Observations 观测值
Variables 变量
Example: people
- each person = observation
- properties (name, age …) = variables
Rows = observations (persons)
Columns = variables (age, name, …)

不同的变量的观测值可以类型不同，但是变量自己的所有观测值类型一致。

多在导入数据时使用。

创建数据框

name <- c("Anne", "Pete", "Frank", "Julia", "Cath") 
age <- c(28, 30, 21, 39, 35) 
child <- c(FALSE, TRUE, TRUE, FALSE, TRUE) 
df <- data.frame(name, age, child) 
str(df)

## 'data.frame':    5 obs. of  3 variables:
##  $ name : Factor w/ 5 levels "Anne","Cath",..: 1 5 3 4 2
##  $ age  : num  28 30 21 39 35
##  $ child: logi  FALSE TRUE TRUE FALSE TRUE

命名数据框

name <- c("Anne", "Pete", "Frank", "Julia", "Cath") 
age <- c(28, 30, 21, 39, 35) 
child <- c(FALSE, TRUE, TRUE, FALSE, TRUE) 
df <- data.frame(name, age, child)
names(df) <- c("Name", "Age", "Child") 
str(df)

## 'data.frame':    5 obs. of  3 variables:
##  $ Name : Factor w/ 5 levels "Anne","Cath",..: 1 5 3 4 2
##  $ Age  : num  28 30 21 39 35
##  $ Child: logi  FALSE TRUE TRUE FALSE TRUE

df <- data.frame(Name = name, Age = age, Child = child) #also
str(df)

## 'data.frame':    5 obs. of  3 variables:
##  $ Name : Factor w/ 5 levels "Anne","Cath",..: 1 5 3 4 2
##  $ Age  : num  28 30 21 39 35
##  $ Child: logi  FALSE TRUE TRUE FALSE TRUE

可见，这里的字符串向量，被自动转化为因子类型，所以可以设置参数来避免此隐含行为。

name <- c("Anne", "Pete", "Frank", "Julia", "Cath") 
age <- c(28, 30, 21, 39, 35) 
child <- c(FALSE, TRUE, TRUE, FALSE, TRUE)
df <- data.frame(name, age, child, 
                   stringsAsFactors = FALSE)
str(df)

## 'data.frame':    5 obs. of  3 variables:
##  $ name : chr  "Anne" "Pete" "Frank" "Julia" ...
##  $ age  : num  28 30 21 39 35
##  $ child: logi  FALSE TRUE TRUE FALSE TRUE

子集运算

Subset Data Frame * Subsetting syntax from matrices and lists * [
from matrices * [[ and $ from lists

name <- c("Anne", "Pete", "Frank", "Julia", "Cath") 
age <- c(28, 30, 21, 39, 35) 
child <- c(FALSE, TRUE, TRUE, FALSE, TRUE) 
people <- data.frame(name, age, child,  
               stringsAsFactors = FALSE)

# 类似矩阵的操作
people[3,2] 

## [1] 21

people[3,"age"]

## [1] 21

people[,"age"]

## [1] 28 30 21 39 35

people[3,] # 由于返回的是一个数据框，我的R notebook不显示数据框

##    name age child
## 3 Frank  21  TRUE

people[c(3, 5), c("age", "child")] # 同上

##   age child
## 3  21  TRUE
## 5  35  TRUE

# 类似列表的操作
people$age

## [1] 28 30 21 39 35

people[["age"]]

## [1] 28 30 21 39 35

people[[2]]

## [1] 28 30 21 39 35

## 由于返回的是一个数据框，我的R notebook不显示数据框
people["age"]

##   age
## 1  28
## 2  30
## 3  21
## 4  39
## 5  35

people[2]

##   age
## 1  28
## 2  30
## 3  21
## 4  39
## 5  35

扩展数据框

Extend Data Frame * Add columns = add variables * Add rows = add
observations

name <- c("Anne", "Pete", "Frank", "Julia", "Cath") 
age <- c(28, 30, 21, 39, 35) 
child <- c(FALSE, TRUE, TRUE, FALSE, TRUE) 
people <- data.frame(name, age, child,  
               stringsAsFactors = FALSE)
#Add column
height <- c(163, 177, 163, 162, 157) 
people$height <- height 
str(people)

## 'data.frame':    5 obs. of  4 variables:
##  $ name  : chr  "Anne" "Pete" "Frank" "Julia" ...
##  $ age   : num  28 30 21 39 35
##  $ child : logi  FALSE TRUE TRUE FALSE TRUE
##  $ height: num  163 177 163 162 157

##also
people[["height"]] <- height
str(people)

## 'data.frame':    5 obs. of  4 variables:
##  $ name  : chr  "Anne" "Pete" "Frank" "Julia" ...
##  $ age   : num  28 30 21 39 35
##  $ child : logi  FALSE TRUE TRUE FALSE TRUE
##  $ height: num  163 177 163 162 157

weight <- c(74, 63, 68, 55, 56) 
cbind(people, weight)

##    name age child height weight
## 1  Anne  28 FALSE    163     74
## 2  Pete  30  TRUE    177     63
## 3 Frank  21  TRUE    163     68
## 4 Julia  39 FALSE    162     55
## 5  Cath  35  TRUE    157     56

#Add row 这里要注意，有时候会出错
tom <- data.frame("Tom", 37, FALSE, 183)
#rbind(people, tom)
#会报错：
#Error : names do not match previous names
tom <- data.frame(name = "Tom", age = 37, 
            child = FALSE, height = 183)
rbind(people, tom) 

##    name age child height
## 1  Anne  28 FALSE    163
## 2  Pete  30  TRUE    177
## 3 Frank  21  TRUE    163
## 4 Julia  39 FALSE    162
## 5  Cath  35  TRUE    157
## 6   Tom  37 FALSE    183

排序

这里主要介绍了sort()与order()，其中，order()更适合用来为数据框调整顺序。

str(people)

## 'data.frame':    5 obs. of  4 variables:
##  $ name  : chr  "Anne" "Pete" "Frank" "Julia" ...
##  $ age   : num  28 30 21 39 35
##  $ child : logi  FALSE TRUE TRUE FALSE TRUE
##  $ height: num  163 177 163 162 157

#sort()直接对于向量元素进行了排序
sort(people$age)

## [1] 21 28 30 35 39

#order()会返回对应大小等级所实际在的位置
ranks <- order(people$age) 
ranks

## [1] 3 1 2 5 4

people$age

## [1] 28 30 21 39 35

people[ranks, ] #直接对行进行了排序

##    name age child height
## 3 Frank  21  TRUE    163
## 1  Anne  28 FALSE    163
## 2  Pete  30  TRUE    177
## 5  Cath  35  TRUE    157
## 4 Julia  39 FALSE    162

#或者如下可以实现降序排序
people[order(people$age, decreasing = TRUE), ] 

##    name age child height
## 4 Julia  39 FALSE    162
## 5  Cath  35  TRUE    157
## 2  Pete  30  TRUE    177
## 1  Anne  28 FALSE    163
## 3 Frank  21  TRUE    163

绘图 Graphics

这里主要介绍了graphics包的plot()与hist()

plot()会根据不同的数据类型，而画出不同的图像

plot() (categorical) 条形图例如：plot(countries$continent)
plot() (numerical) 散点图例如：plot(countries$population)
plot() (2x numerical) 散点图
例如：plot(countries$area, countries$population)、
plot(log(countries$area), log(countries$population))
plot() (2x categorical) 某种条形图的变形
例如：plot(countries$continent, countries$religion)

hist()可以绘制直方图例如： hist(africa$population)、
hist(africa$population, breaks = 10)

Other graphics functions * barplot() * boxplot() * pairs()

自定义绘图

这里就是修改参数了。无需多讲。

这里，引出了函数par()，这是一个绘图的公共参数列表，里面存放着常用的一些绘图的公共属性，可以实现绘制多幅图形时，基本属性的一次性确定。

例如：

par(col = "blue") 
plot(mercury$temperature, mercury$pressure)

常用的plot的属性有：

plot(mercury$temperature, mercury$pressure, 
       xlab = "Temperature", 
       ylab = "Pressure", 
       main = "T vs P for Mercury", #标题
       type = "o", 
       col = "orange", 
       col.main = "darkgray", 
       cex.axis = 0.6, #cex系列属性表示缩放程度
       lty = 5, #Line Type
       pch = 4  #Plot Symbol
       )

多图绘制

mfrow与mfcol参数可以在一个图形框里，用来放置多个图像，区别是，前者是将后面plot语句生成的图像按行填充，而后者是按列填充。

#按行填充
par(mfrow = c(2,2)) 
plot(shop$ads, shop$sales) 
plot(shop$comp, shop$sales) 
plot(shop$inv, shop$sales) 
plot(shop$size_dist, shop$sales)

#按列填充
par(mfcol = c(2,2)) 
plot(shop$ads, shop$sales) 
plot(shop$comp, shop$sales) 
plot(shop$inv, shop$sales) 
plot(shop$size_dist, shop$sales)

Reset the grid

par(mfrow = c(1,1))

相较于这个，layout()函数设置的更为灵活。

grid <- matrix(c(1, 1, 2, 3), nrow = 2, 
         ncol = 2, byrow = TRUE) 
layout(grid)
plot(shop$ads, shop$sales) #放在grid的1号位置
plot(shop$comp, shop$sales) #放在grid的2号位置
plot(shop$inv, shop$sales) #放在grid的3号位置

Reset the grid

layout(1) 
par(mfcol = c(1,1))

Reset all parameters

old_par <- par() 
par(col = "red") 
plot(shop$ads, shop$sales) 
par(old_par) 
plot(shop$ads, shop$sales)

线性拟合

引出函数lm() —— *linear
model*，**lm(a~b)就是对a=k*b+c进行线性拟合**

plot(shop$ads, shop$sales, 
      pch = 16, col = 2, 
      xlab = "advertisement", 
      ylab = "net sales")
lm_sales <- lm(shop$sales ~ shop$ads)
abline(coef(lm_sales), lwd = 2) #取模型系数，线宽为2，画直线

R语言-数据结构

工作空间相关

基本数据类型

强制转换

向量 Vector

创建 `c()`或者利用`:`

命名 `names()`

单值仍为向量

强制变换

基本运算

子集

矩阵 Matrix

创建 `matrix()`

命名

强制转换

子集运算

矩阵运算

因子 Factors

创建因子 `factor()`

Rename factor levels

Ordered factor

列表 List

创建列表 `list()`

命名列表

列表嵌套

子集运算

列表扩展

数据框 Data Frame

创建数据框

命名数据框

子集运算

扩展数据框

排序

绘图 Graphics

自定义绘图

多图绘制

线性拟合

lart

引用和评论

PyTorch之Checkpoint机制解析

R语言-数据结构

工作空间相关

基本数据类型

强制转换

向量 Vector

创建 c()或者利用:

命名 names()

单值仍为向量

强制变换

基本运算

子集

矩阵 Matrix

创建 matrix()

命名

强制转换

子集运算

矩阵运算

因子 Factors

创建因子 factor()

Rename factor levels

Ordered factor

列表 List

创建列表 list()

命名列表

列表嵌套

子集运算

列表扩展

数据框 Data Frame

创建数据框

命名数据框

子集运算

扩展数据框

排序

绘图 Graphics

自定义绘图

多图绘制

线性拟合

lart

引用和评论

PyTorch之Checkpoint机制解析

创建 `c()`或者利用`:`

命名 `names()`

创建 `matrix()`

创建因子 `factor()`

创建列表 `list()`