R language Learning (ii)

1. Vector of complex numbers: generating complex vectors with the complex () function

EX:

> X<-seq (-PI,PI,BY=PI/10)%x value

> Y<-sin (x)%y value
> Z<-complex (re=x,im=y)%re as the real part, IM for the complex part

> Plot (z); lines (z)% drawing graphics

Run as follows:

2. Subscript operation of vectors

The R software provides very flexible access to vector elements and functions to the quantum set, and an element of the x vector can be accessed in the X[i] format

EX:

> x<-c (1,4,7)
> X[2]
[1] 4
> (c (1,3,5) +5) [2]
[1] 8

You can change the value of an element individually

> x[2]<-125
> x
[1] 1 125 7
> x[c (1,3)]<-c (144,169)
> x
[1] 144 125 169

3. Logical vector

V and x equal-length logical vectors, x[v] represent the removal of all elements of the V as Truth, Ex:

> x<-c (1,4,7)
> x<5
[1] True True FALSE
> X[x<5]
[1] 1 4

Vector missing data can be assigned to 0

EX:

> z<-c ( -1,1:3,na)
> z[is.na (z)]<-0
> Z
[1]-1 1 2 3 0

You can assign the non-missing data in the vector to another vector

EX:

> Y<-z[!is.na (z)]
> y
[1]-1 1 2 3

Do the corresponding calculations

> (z+1) [(!is.na (z)) &z>0]->x
> x
[1] 2 3 4

4. Positive integer operation of subscript

V is a vector, the subscript value between 1 to Length (v), the value allowed to repeat, EX:

V<-10:20

V[c (1,3,5,9)]

[1] 10 12 14 18

5. Negative integer operations on the underlying

V is a vector, the subscript value is between-lenght () and-1, EX:

> v<-10:20
> v[-(1:5)]
[1] 15 16 17 18 19 20

Represents the deduction of the corresponding element

6. Small-scale operation with a character value

> ages<-c (li=33,zhang=29,liu=18)
> Ages
Li Zhang Liu
33 29 18

> ages["Zhang"]
Zhang
29

You can add a name to a vector.

> fruit<-c (5,10,1,20)

> Names (Fruit) <-c ("Orange", "banana", "apple", "peach")
> Fruit
Orange Banana Apple Peach
5 10 1 20

R language Learning (ii)