1. Tavis Rudd
  2. r_users_group_2

Source

r_users_group_2 / exercises / README.txt

                                README
                                ======

Author: Tavis Rudd
Date: 2011-05-17 17:01:35 PDT


Table of Contents
=================
1 hello world 
2 hello.world function 
3 create an anonymous version of the same function 
4 use Google to figure out what R's rules are for naming variables and functions 
5 hello(name) function 
6 hello(name) with a default argument 
7 create a `vector` of the following strings and assign it to a variable 
8 use help.search to find a function that can convert each element in that vector to uppercase 
9 find a function that will give you the length of the vector 
10 figure out the syntax to get the third element in the vector 
11 create a function that applies another function to each element in a vector 
12 find a function that will create a sequence of integers 
13 use that function and the `matrix` function to create a 4 x 5 matrix of the first 20 natural numbers 
14 figure out the syntax to get the matrix element at row 2, col 3 
15 multiply every element in the matrix by 3 
16 find a function that gives you the dimensions of the matrix 
17 convert this matrix to a vector 
18 create a Boolean matrix of the same size 
19 use the Boolean matrix to take a subset of our first matrix 
20 what is the type of the subset 
21 figure out how to create a random sample of 100 integers 
22 take a random sample of five elements from your first matrix 
23 find the built-in dataset `swiss` and the help information about it 
24 what are the `type`, `dimensions`, `structure`, and `dimension names` of this dataset 
25 figure out how to access each column of this dataset individually 
26 show the first and last six elements of this dataset 
27 what are the types of the columns in `swiss` 


1 hello world 
--------------
Start the R interpreter and print the string "hello world"

2 hello.world function 
-----------------------
Create a function called hello.world that does what you did manually
in the previous exercise. 

3 create an anonymous version of the same function 
---------------------------------------------------

4 use Google to figure out what R's rules are for naming variables and functions 
---------------------------------------------------------------------------------

5 hello(name) function 
-----------------------
Create a variant of the previous function that accepts a `name`
parameter and prints "Hello Mary", "Hello Lamb", etc. 

Hint: you'll need to figure out how to concatenate/join strings

6 hello(name) with a default argument 
--------------------------------------
Give the `name` argument a default value.

7 create a `vector` of the following strings and assign it to a variable 
-------------------------------------------------------------------------
"Mary", "had", "a", "little", "lamb"

8 use help.search to find a function that can convert each element in that vector to uppercase 
-----------------------------------------------------------------------------------------------

9 find a function that will give you the length of the vector 
--------------------------------------------------------------

10 figure out the syntax to get the third element in the vector 
----------------------------------------------------------------

11 create a function that applies another function to each element in a vector 
-------------------------------------------------------------------------------

12 find a function that will create a sequence of integers 
-----------------------------------------------------------
This is like the `range` function in Python.

13 use that function and the `matrix` function to create a 4 x 5 matrix of the first 20 natural numbers 
--------------------------------------------------------------------------------------------------------

14 figure out the syntax to get the matrix element at row 2, col 3 
-------------------------------------------------------------------

15 multiply every element in the matrix by 3 
---------------------------------------------

16 find a function that gives you the dimensions of the matrix 
---------------------------------------------------------------

17 convert this matrix to a vector 
-----------------------------------

18 create a Boolean matrix of the same size 
--------------------------------------------
... that indicates whether the elements in our first matrix are > 13

19 use the Boolean matrix to take a subset of our first matrix 
---------------------------------------------------------------
... where the condition is true
... and where it is false

20 what is the type of the subset 
----------------------------------

21 figure out how to create a random sample of 100 integers 
------------------------------------------------------------

22 take a random sample of five elements from your first matrix 
----------------------------------------------------------------

23 find the built-in dataset `swiss` and the help information about it 
-----------------------------------------------------------------------

24 what are the `type`, `dimensions`, `structure`, and `dimension names` of this dataset 
-----------------------------------------------------------------------------------------

25 figure out how to access each column of this dataset individually 
---------------------------------------------------------------------

26 show the first and last six elements of this dataset 
--------------------------------------------------------
hint: there are built in functions that will do this for you

27 what are the types of the columns in `swiss` 
------------------------------------------------