# Built-in R Features - Data Structures¶

R contains quite a few useful built-in functions to work with data structures. Here are some of the key functions to know:

- seq(): Create sequences
- sort(): Sort a vector
- rev(): Reverse elements in object
- str(): Show the structure of an object
- append(): Merge objects together (works on vectors and lists)

In [8]:

    # seq(start,end,step size)
    seq(0, 100, by = 3)

Out[8]:

1. 0
2. 3
3. 6
4. 9
5. 12
6. 15
7. 18
8. 21
9. 24
10. 27
11. 30
12. 33
13. 36
14. 39
15. 42
16. 45
17. 48
18. 51
19. 54
20. 57
21. 60
22. 63
23. 66
24. 69
25. 72
26. 75
27. 78
28. 81
29. 84
30. 87
31. 90
32. 93
33. 96
34. 99

In [10]:

    v <- c(1,4,6,7,2,13,2)

In [14]:

    sort(v)

Out[14]:

1. 1
2. 2
3. 2
4. 4
5. 6
6. 7
7. 13

In [15]:

    sort(v,decreasing = TRUE)

Out[15]:

1. 13
2. 7
3. 6
4. 4
5. 2
6. 2
7. 1

In [18]:

    v2 <- c(1,2,3,4,5)
    rev(v2)

Out[18]:

1. 5
2. 4
3. 3
4. 2
5. 1

In [20]:

    str(v)

     num [1:7] 1 4 6 7 2 13 2

In [22]:

    append(v,v2)

Out[22]:

1. 1
2. 4
3. 6
4. 7
5. 2
6. 13
7. 2
8. 1
9. 2
10. 3
11. 4
12. 5

In [23]:

    sort(append(v,v2))

Out[23]:

1. 1
2. 1
3. 2
4. 2
5. 2
6. 3
7. 4
8. 4
9. 5
10. 6
11. 7
12. 13

### Data Types¶

- is.*(): Check the class of an R object
- as.*(): Convert R objects

In [1]:

    v <- c(1,2,3)
    is.vector(v)

Out[1]:
TRUE
In [2]:

    is.list(v)

Out[2]:
FALSE
In [3]:

    as.list(v)

Out[3]:

1. 1
2. 2
3. 3

In [4]:

    as.matrix(v)

Out[4]:

1
2
3

Great! That's if for the built-in data structure functions! These will com ein handy so try to remember them for the exercises!