R Language Programming Art # data type vector (vector)

The most basic data type of R language-vectors (vector)

1, insert the vector element, all elements in the same vector must be the same pattern (data type), such as Integer, numeric (floating-point), character (string), logical, plural, and so on. View the type of the variable can be queried using the typeof (X) function.

> #插入向量元素 > x <-C (88,5,12,13) > X[1]  5 13> x <-C (x[1:3],168,x[4]) #插入168数字在13之前 > x[1]  8 8   5  12 168  

2, delete the elements in the vector, because the vector in R is continuously stored, it is not possible to insert or delete the element (so the above insert code actually re-creates a new vector and then points x to the new vector, similar to the pointer in C)

> #删除向量中的元素 ^_^ > X[1]   5  168  13> x <-C (88,5,168,13) > X[1]   5 168  

3, get the long vector

> #获取向量的长量 > X[1]   5 168  

4. Iterate through all the elements in the vector

> #第一种方法 because 1:length (x) = (1,0), actually made two iterations > first1function (x) {for (I in 1:length (x)) {    

> #第二种方法 generates a linear sequence with the SEQ function, with an element interval of 1, which solves the first inefficient method > First2 <-function (x) {+ for     (i in SEQ (x)) {+         if (x[i]==1) break+     }+     

5, vector and array, matrix array and matrix including the list, in a sense is actually a vector. It's just that they have extra class properties. such as: The Matrix has the number of rows and more.

> M <-Matrix (C (1,2,3,4), nrow = 2,byrow = T) > M     [, 1] [, 2][1,]    1    2[2,]    3    4> m + 10:13     [, 1] [, 2] [1,]   14[2,]   14   

Here the 2x2 matrix M is stored as a four-tuple vector, i.e. (1,2,3,4), and is stored as two lines, sorted by rows, and then added (10,11,12,13) to it, with the latest matrix, equivalent to the following code

> M <-Matrix (C (1,3,2,4), nrow = 2) > M     [, 1] [, 2][1,]    1    2[2,]    3    4> m + 10:13     [, 1] [, 2][ 1,]   14[2,]   14   

6, loop completion when using operators on two vectors, if the two vectors are required to have the same length, R automatically loops over (recycle), which repeats the shorter vector until it matches the length of another vector

> C (1,2,4) + C (6,0,9,20,22) [1]  7  2 24Warning message:in C (1, 2, 4) + C (6, 0, 9, 20, 22):  

Equivalent to the following code:

> C (1,2,4,1,2) + C (6,0,9,20,22) [1]  7  

#矩阵

> x <-Matrix (C (1,2,3,4,5,6), nrow = 3) > x     [, 1] [, 2][1,]    1    4[2,]    2    5[3,]    3    6> x + C (up to)     [, 1] [, 2] [1,]    2    6[2,]    4    6[3,]    4    

#矩阵循环补齐

> x <-Matrix (C (1,2,3,4,5,6), nrow = 3) > x     [, 1] [, 2][1,]    1    4[2,]    2    5[3,]    3    6> y <-Matrix (C (1,2,1,2,1,2), nrow = 3) > y     [, 1] [, 2][1,]    1    2[2,]    2    1[3,]    1    2> x + Y     [, 1] [, 2][1,]    2    6[2,]    4    6[3,]    4    

Equivalent:

　　　　

7. Common vector operations include arithmetic and logic operations, vector indexing, creating vectors, etc.

#R是一种函数式语言, it's every shipping symbol (+-*/...) ) are actually all functions

#加法 > 2+3[1] 5> "+" (2,3) [1] 5>>c (+) + C (3,4) >[1] 4  6>> "+" (2,3,4) Error in ' + ' (2, 3, 4): O Perator needs one or both arguments> #乘法 > C (+) * C (3,4) [1] 3 8> #减法 > C (3,4)-C (+) [1] 2 2> #除法 > C ( 3,4)/C (on) [1] 3 2> #取余 > C (3,4) percent C (2,3) [1] 1 1>

8. The most important and most common operator in the vector index R is the index, which is used to select the elements of a specific index in the directed amount to form a sub-vector. The format of the index vector is x[y] (x, y are vectors), which returns the result of those elements in X that are indexed as Y.

R Language Programming Art # data type vector (vector)