* Resources
- http://www.statmethods.net/index.html (or google quick-r)
- type ? followed by a function name to see built-in help
- help.search function
* hello world
Start the R interpreter and print the string "hello world"
* hello.world function
Create a function called hello.world that does what you did manually
in the previous exercise.
* create an anonymous version of the same function
* use Google to figure out what R's rules are for naming variables and functions
* 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
* hello(name) with a default argument
Give the `name` argument a default value.
* create a `vector` of the following strings and assign it to a variable
"Mary", "had", "a", "little", "lamb"
* use help.search to find a function that can convert each element in that vector to uppercase
* find a function that will give you the length of the vector
* figure out the syntax to get the third element in the vector
* create a function that applies another function to each element in a vector
* find a function that will create a sequence of integers
This is like the `range` function in Python.
* use that function and the `matrix` function to create a 4 x 5 matrix of the first 20 natural numbers
* figure out the syntax to get the matrix element at row 2, col 3
* multiply every element in the matrix by 3
* find a function that gives you the dimensions of the matrix
* convert this matrix to a vector
* create a Boolean matrix of the same size
... that indicates whether the elements in our first matrix are > 13
* use the Boolean matrix to take a subset of our first matrix
... where the condition is true
... and where it is false
* what are the type and dimensions of the subset
* figure out how to create a random sample of 100 integers
* take a random sample of five elements from your first matrix
* find a way to sort the result of that sampling
* create a `list` that contains the letters of English and
... and their position in the alphabet as separate fields
hint: letters is a constant built-in to R
* find the built-in dataset `swiss` and the help information about it
* what are the `type`, `dimensions`, `structure`, and `dimension names` of this dataset
* figure out how to access each column of this dataset individually
* show the first and last six elements of this dataset
hint: there are built in functions that will do this for you
* what are the types of the columns in `swiss`
* create a subset of swiss that only includes the columns Catholic and Fertility
* create a subset only showing the regions that are at least 50% Catholic
* use the functions that Isabella mentioned to examine the swiss data
* look at the `airquality` built-in dataset and create a subset without the NA Ozone values removed
* plot the various dimensions of the airquality dataset
* advanced exercise
** work in groups to choose some line-based log data (like apache logs, syslog, etc.)
** use `awk`, `perl`, `sed` or similar to select a subset (match a regular expression) and output csv
** save the output into a csv file and then import into R
** use what you've learnt so far to explore, summarize and plot the data