Dear Olivia,
Could you please add Eddie Malesky (also an academy fellow who is auditing
the class) to the class email list (emalesky(a)wcfia.harvard.edu).
Thank you!
Gretchen
----- Original Message Follows -----
Hi, everyone.
Kate had some good questions. For a program template, look at Zelig,
Chapter 6, Section 2.1. For those of you who find this oenerous, the
program looks like this:
check <- function(p, q) {
result <- (p-q)/q
result
}
check(4, 5) # or check(p = 4, q = 5)
Several things to note:
* The curly braces {} enclose the commands that the program will
perform.
* The parentheses () are to define the arguments that go into the
function (or for mathematical operations, as in line 2).
* The <- stores symbols. So line 1 stores the function as check (we
run the function by typing check and the arugments), but the second
arrow in line 2 stores information only within the function itself (you
can't find results once you exit the function), so you have to make
sure that you return the function's output in the last line of the
function (as in line 3).
* When writing code, more spaces are better -- this makes your code
readable.
* Please comment your code so I know what's going on. If your
function bombs but you comment your code, you will get partial credit.
* If you want to check your OLS function, you can use zelig(....,
model = "ls").
On Kate's second question, you can use any text editor (Notepad, Wordpad
, Microsoft Word), but this makes formatting your code more difficult.
One of the neat things about XEmacs is that it highlights your braces
and indents your code so you can see where you're going wrong.
Also, I discovered that the set up on the course web site for Windows
XEmacs lets you export your graphics to a file that you can put in a
Word document, if you don't want to use latex. If you go through the
process of setting up Windows XEmacs, you'll still learn to use R
properly, but you'll be able to use Word (until you learn TeX).
Keep the questions coming. 8)
Yours, Olivia
----- Original Message -----
From: "Kate Emans" <emans(a)fas.harvard.edu>
To: <olau(a)fas.harvard.edu>
Sent: Friday, September 24, 2004 3:32 PM
Subject: request for simple program example
Hi Olivia!
1) I've been pondering R and trying to filter all the information. I
think (and I suspect others will agree) that it is not too hard to
figure out how to use individual commands. But it is difficult w/
out knowing R set-up, what is the basic syntax for a simple
"program."
>
I'm wondering if you could send us an
example, sort of a template, for
a very simple R program that we could use as an example? Of course I
don't want you to give away how to do anything in the prob set, so it
could be a program that does something simple: like make two
matricies and multiply them. But I think it would really help just
to see the basic set up from start to finish of a simple program and
what exactly this looks like; what are the good basic commands to
start and end with and how do they string together. THis is hard to
get from the
manual. >
2) Also, a specific question: can we use any text
editor to create a
program of R commands? Obviously learning Emacs is desirable but if
we can't do it quite yet, will any text editor work, or just that
one? >
THanks very much for your help. I send this to
you and not hte whole
list so if you think question one is unreasonable you will not be
pressured to do it! But if you answer you can send to the whole list
along w/ my question.
:) Kate
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