R语言关于变量的知识点总结

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
# Assignment using equal operator.
var.1 = c(0,1,2,3)   

# Assignment using leftward operator.
var.2 <- c("learn","R") 

# Assignment using rightward operator. 
c(TRUE,1) -> var.3   

print(var.1)
cat ("var.1 is ", var.1 ,"
")
cat ("var.2 is ", var.2 ,"
")
cat ("var.3 is ", var.3 ,"
")

1
2
3
4
[1] 0 1 2 3
var.1 is 0 1 2 3 
var.2 is learn R 
var.3 is 1 1

1
2
3
4
5
6
7
8
9
10
11
var_x <- "Hello"
cat("The class of var_x is ",class(var_x),"
")

var_x <- 34.5
cat(" Now the class of var_x is ",class(var_x),"
")

var_x <- 27L
cat(" Next the class of var_x becomes ",class(var_x),"
")

1
2
3
The class of var_x is character 
 Now the class of var_x is numeric 
  Next the class of var_x becomes integer

1
print(ls())

1
2
3
[1] "my var"  "my_new_var" "my_var"  "var.1"  
[5] "var.2"  "var.3"  "var.name" "var_name2."
[9] "var_x"  "varname"

1
2
# List the variables starting with the pattern "var".
print(ls(pattern = "var"))

1
2
3
[1] "my var"  "my_new_var" "my_var"  "var.1"  
[5] "var.2"  "var.3"  "var.name" "var_name2."
[9] "var_x"  "varname"

1
print(ls(all.name = TRUE))

1
2
3
[1] ".cars"  ".Random.seed" ".var_name" ".varname"  ".varname2" 
[6] "my var"  "my_new_var" "my_var"  "var.1"  "var.2"  
[11]"var.3"  "var.name"  "var_name2." "var_x"

1
2
rm(var.3)
print(var.3)

1
2
[1] "var.3"
Error in print(var.3) : object 'var.3' not found

1
2
rm(list = ls())
print(ls())

1
character(0)