I have used both SAS and R for projects large and small. Each has its own use, but I strongly disagree with the SAS marketing rep's argument that "We have customers who build engines for aircraft. I am happy they are not using freeware when I get on a jet." Actually, I would find it terrifying to think about the engineers using canned packages that are subject to no external review whatsoever, rather than R and its routines, which are freely available for all to see.
When choosing between the two, there are two questions I would ask: 1) What format does my data come in? 2) Is my data small enough to fit in memory? If the answer to 1 is "SAS dataset" or the answer to 2 is "NO" then I would use SAS. It keeps datasets on disk, so if you are handling TBs (or even GBs) of data, there is no better software package. A lot of big data dumps come in SAS, too, so while it is easy to dump to CSV, if you are repeatedly accessing the same data source, SAS makes sense. Also, if you already have significant infrastructure written in SAS (data processing, reporting, etc.) it may make sense to continue doing it that way.
In all other cases (and even in some of the above cases, when considering overall cost), R is better. Easier to program in; easier to write C/Fortran/Python/etc. extensions for; contains real functions (SAS just has macros); object oriented; and FREE (GPL and zero cost). That last bit is important because if for some reason the SAS Institute goes bust (stranger things have happened), and all of your code is in SAS, you are fucked. Whereas if you have been writing in R, you will always have your existing software and can, in principle, continue developing it yourself or hire someone to maintain/upgrade it for you.
R is great, even if it is a slightly awkward language. It easily blows Octave out of the water in almost every way, but is inferior (as a language) to python+scipy, although I believe that it has far more packages available for it. Just check out CRAN some day. It's amazing.
VaR is meaningless. As the article pointed out, all it says is that you won't lose more than X 99% (or some other percentage) of the time. VaR tells you nothing about the performance of your portfolio in really bad conditions (that 1%). Because of this, it actually encourages traders to take risky bets where most of the time the trade does fine and 1% of the time it is bad enough to wipe out the whole company. VaR only gives you the threshold. It says nothing of what happens once you cross the threshold. The "advantage" (curse) of VaR is that it is intuitive and easy to understand. Of course you cannot summarize the entire balance sheet of a company like Citigroup in a single number that is so easy to understand. There are certain risk measures that are more complicated to define, but give some description of the tail distribution (i.e., give some idea of how bad things will get in that 1%).
These are so-called Coherent Risk Measures and Convex Risk Measures. They encourage diversification (rather than discouraging it as VaR does) and penalize taking on huge amounts of risk for minimal profits. They are not perfect either--ideally one would want to have a sense of the distribution (which is a whole function), rather than just a single number--but they are far better than VaR. VaR is encouraged by regulators and is accepted by banks b/c it allows them to take big risks and make lots of money most of the time. Using better risk measures would go a long way to cleaning up the global financial system.
for python hackers, ipython is essential. it's a wrapper for the python shell which has tab completion of all class/function/method attributes and interactive access to documentation, plus all kinds of other fancy tools. it has made learning python so much easier.
export PAGER=/usr/bin/less export EDITOR=/usr/bin/vim # emacs if you like
# places i ssh to often: alias sshx='ssh user@server-x' # and if i have a command i frequently want to use as a 1-off: alias x-command='sshx command'
# i really hate the pc speaker bell, so i put this in my.profile to disable it xset -b
# also, for linux--get rid of it altogether (as root) by banning the driver module from your kernel: echo -e "#fucking pc speaker\nblacklist pcspkr" >>/etc/modprobe.d/blacklist
actually, yahoo and google (and i would guess a few others) recently started giving live streaming stock quotes without delay. and as of this summer, bloomberg stock quotes were still delayed 15 minutes.
if they are "bottom-feeders" and they are calling your company, what does that say about your employees?
honestly, if you pay your employees well and keep them happy, this is nothing to worry about. if you really are worried, get rid of your electronic phone directory and hire a secretary to screen calls to the switchboard.
while i might be willing to grant you that for individual trading firms, speed is more important than stability, you cannot make that argument for the whole stock exchange. when morgan stanley or some hedge fund loses connectivity, they stop making money for a few hours. no big deal really. if the NYSE goes down, it's a major economic catastrophe. stability and capacity are the most important things! obviously they need speed to keep up with the demands of the traders, but that just translates to high volume for the NYSE's servers.
the trades will be managed by aix and linux will just be used for "ftp transfers on the front end." this would be bulk data transfers, not data feeds and all i/o as other might have suggested. i can pretty much guarantee you that the nyse is not processing trades and sending out live market data (to bloomberg, retuters, etc.) by ftp.
also, i am somewhat concerned by this move in light of the trading disruption at the end of february where the existing (mainframe, i presume) trading systems could not handle all the trades and the data feeds were way behind the actual prices of the securities. i know the nyse is a public for-profit company now, so it's silly to talk about "public interest" but shouldn't there be some regulation about the capacity of their IT infrastructure to make sure that their cost-cutting doesn't cause another 4% decrease in stock market value on an abnormally high trading day?
this is actually the perfect example of begging the question. contrary to popular opinion, "begging the question" does not mean "demanding that the question be asked." it is a form of logical fallacy in which you assume what you are trying to prove.
using the fact that someone was accused of a crime to discredit their defense of that crime is a prime example of begging the question.
the example of "a catch-22" from the book catch-22 is the following: if a pilot is crazy, he will not have to fly more missions (since he will be placed on medical leave). if a pilot does not want to fly more missions, he is not crazy (since he values his own life, therefore he has to fly more missions). so if you're not crazy, you fly more missions. if you say you are crazy, the army assumes you are just trying to save your own life, therefore you are not crazy, and therefore you still fly more missions. that's the quick summary, anyway.
Seriously, time-wasting and silly forwards are a huge part of the Internet. Sure, youtube is listed, but the article emphasizes the usefulness, not the uselessness. The Internet is not such a serious place, after all.
mark cuban. the "internet billionaire" who sold broadcast.com to yahoo in the height of the dot-com bubble and whose job now is to prop up failing IT ventures and piss off NBA Commissioner David Stern. He still gets a lot of notoriety as a great businessman (and writes as if he was one, too) although it would appear that he was mostly just in the right place at the right time.
just curious, but does anyone know if there are any programmers who performed well in their summer of code projects and were subsequently offered jobs at google? i know google was (is) trying to curry favor with the open source community, but i expect they were also scouting talent to some extent as well.
I completely agree with you that AT&T is dead, but the amusing thing is that between SBC, BellSouth, Ameritech, AT&T Wireless, AT&T, and I don't know what else they have a large portion of the former AT&T Corporation that was broken up for antitrust reasons.
There was an article in the Wall Street Journal a few weeks ago about how iPod accessories are now a billion dollar market. Seriously. They indicated that Apple would be expanding into this business to increase its revenue streams from the iPod, so I guess that's what this is. Apple sure knows how to complement its own products with beautifully designed accessories. Others look clunky by comparison (although I must say that the Bose SoundDock does look better than the Apple iPod Hi-Fi, and it's cheaper).
Slashdot Mirror
I have used both SAS and R for projects large and small. Each has its own use, but I strongly disagree with the SAS marketing rep's argument that "We have customers who build engines for aircraft. I am happy they are not using freeware when I get on a jet." Actually, I would find it terrifying to think about the engineers using canned packages that are subject to no external review whatsoever, rather than R and its routines, which are freely available for all to see.
When choosing between the two, there are two questions I would ask:
1) What format does my data come in?
2) Is my data small enough to fit in memory?
If the answer to 1 is "SAS dataset" or the answer to 2 is "NO" then I would use SAS. It keeps datasets on disk, so if you are handling TBs (or even GBs) of data, there is no better software package. A lot of big data dumps come in SAS, too, so while it is easy to dump to CSV, if you are repeatedly accessing the same data source, SAS makes sense. Also, if you already have significant infrastructure written in SAS (data processing, reporting, etc.) it may make sense to continue doing it that way.
In all other cases (and even in some of the above cases, when considering overall cost), R is better. Easier to program in; easier to write C/Fortran/Python/etc. extensions for; contains real functions (SAS just has macros); object oriented; and FREE (GPL and zero cost). That last bit is important because if for some reason the SAS Institute goes bust (stranger things have happened), and all of your code is in SAS, you are fucked. Whereas if you have been writing in R, you will always have your existing software and can, in principle, continue developing it yourself or hire someone to maintain/upgrade it for you.
R is great, even if it is a slightly awkward language. It easily blows Octave out of the water in almost every way, but is inferior (as a language) to python+scipy, although I believe that it has far more packages available for it. Just check out CRAN some day. It's amazing.
Actually, calculations in R are just vectorized. Internally, there must be some looping, but the language hides it.
VaR is meaningless. As the article pointed out, all it says is that you won't lose more than X 99% (or some other percentage) of the time. VaR tells you nothing about the performance of your portfolio in really bad conditions (that 1%). Because of this, it actually encourages traders to take risky bets where most of the time the trade does fine and 1% of the time it is bad enough to wipe out the whole company. VaR only gives you the threshold. It says nothing of what happens once you cross the threshold. The "advantage" (curse) of VaR is that it is intuitive and easy to understand. Of course you cannot summarize the entire balance sheet of a company like Citigroup in a single number that is so easy to understand. There are certain risk measures that are more complicated to define, but give some description of the tail distribution (i.e., give some idea of how bad things will get in that 1%).
These are so-called Coherent Risk Measures and Convex Risk Measures. They encourage diversification (rather than discouraging it as VaR does) and penalize taking on huge amounts of risk for minimal profits. They are not perfect either--ideally one would want to have a sense of the distribution (which is a whole function), rather than just a single number--but they are far better than VaR. VaR is encouraged by regulators and is accepted by banks b/c it allows them to take big risks and make lots of money most of the time. Using better risk measures would go a long way to cleaning up the global financial system.
watching their customers dropping like flies...
see comment below about ARM shipping 1 billion processors last quarter
is there going to be a PC version of SFIV? I only saw ps3 and xbox360 versions. seeing as i have neither of those, but i do have a pc...
oh please tell me you are not toying with my emotions.
http://justfuckinggoogleit.com/search.pl?query=pagers
for python hackers, ipython is essential. it's a wrapper for the python shell which has tab completion of all class/function/method attributes and interactive access to documentation, plus all kinds of other fancy tools. it has made learning python so much easier.
try
du --max-depth=1
a lesson learned the hard way: don't drink and root
if you like vi and diff, you'll LOVE vimdiff
it brings up the two files next to each other and highlights all the differences. quite a beautiful thing.
sudo -s works
(brings up a shell)
export PAGER=/usr/bin/less
export EDITOR=/usr/bin/vim # emacs if you like
# places i ssh to often:
alias sshx='ssh user@server-x'
# and if i have a command i frequently want to use as a 1-off:
alias x-command='sshx command'
# i really hate the pc speaker bell, so i put this in my .profile to disable it
xset -b
# also, for linux--get rid of it altogether (as root) by banning the driver module from your kernel: /etc/modprobe.d/blacklist
echo -e "#fucking pc speaker\nblacklist pcspkr" >>
actually, i was going to say:
du -a --max-depth=1 | sort -n
does the same thing, but more explicitly. then if you want everything:
du -a | sort -n
or just things on your current filesystem:
du -ax | sort -n
for straight summaries, du -cks is crap. instead use:
du -sh
actually, yahoo and google (and i would guess a few others) recently started giving live streaming stock quotes without delay. and as of this summer, bloomberg stock quotes were still delayed 15 minutes.
if they are "bottom-feeders" and they are calling your company, what does that say about your employees?
honestly, if you pay your employees well and keep them happy, this is nothing to worry about. if you really are worried, get rid of your electronic phone directory and hire a secretary to screen calls to the switchboard.
while i might be willing to grant you that for individual trading firms, speed is more important than stability, you cannot make that argument for the whole stock exchange. when morgan stanley or some hedge fund loses connectivity, they stop making money for a few hours. no big deal really. if the NYSE goes down, it's a major economic catastrophe. stability and capacity are the most important things! obviously they need speed to keep up with the demands of the traders, but that just translates to high volume for the NYSE's servers.
the trades will be managed by aix and linux will just be used for "ftp transfers on the front end." this would be bulk data transfers, not data feeds and all i/o as other might have suggested. i can pretty much guarantee you that the nyse is not processing trades and sending out live market data (to bloomberg, retuters, etc.) by ftp.
also, i am somewhat concerned by this move in light of the trading disruption at the end of february where the existing (mainframe, i presume) trading systems could not handle all the trades and the data feeds were way behind the actual prices of the securities. i know the nyse is a public for-profit company now, so it's silly to talk about "public interest" but shouldn't there be some regulation about the capacity of their IT infrastructure to make sure that their cost-cutting doesn't cause another 4% decrease in stock market value on an abnormally high trading day?
this is actually the perfect example of begging the question. contrary to popular opinion, "begging the question" does not mean "demanding that the question be asked." it is a form of logical fallacy in which you assume what you are trying to prove.
using the fact that someone was accused of a crime to discredit their defense of that crime is a prime example of begging the question.
the example of "a catch-22" from the book catch-22 is the following: if a pilot is crazy, he will not have to fly more missions (since he will be placed on medical leave). if a pilot does not want to fly more missions, he is not crazy (since he values his own life, therefore he has to fly more missions). so if you're not crazy, you fly more missions. if you say you are crazy, the army assumes you are just trying to save your own life, therefore you are not crazy, and therefore you still fly more missions. that's the quick summary, anyway.
hamsterdance.com
Seriously, time-wasting and silly forwards are a huge part of the Internet. Sure, youtube is listed, but the article emphasizes the usefulness, not the uselessness. The Internet is not such a serious place, after all.
mark cuban. the "internet billionaire" who sold broadcast.com to yahoo in the height of the dot-com bubble and whose job now is to prop up failing IT ventures and piss off NBA Commissioner David Stern. He still gets a lot of notoriety as a great businessman (and writes as if he was one, too) although it would appear that he was mostly just in the right place at the right time.
just curious, but does anyone know if there are any programmers who performed well in their summer of code projects and were subsequently offered jobs at google? i know google was (is) trying to curry favor with the open source community, but i expect they were also scouting talent to some extent as well.
I completely agree with you that AT&T is dead, but the amusing thing is that between SBC, BellSouth, Ameritech, AT&T Wireless, AT&T, and I don't know what else they have a large portion of the former AT&T Corporation that was broken up for antitrust reasons.
There was an article in the Wall Street Journal a few weeks ago about how iPod accessories are now a billion dollar market. Seriously. They indicated that Apple would be expanding into this business to increase its revenue streams from the iPod, so I guess that's what this is. Apple sure knows how to complement its own products with beautifully designed accessories. Others look clunky by comparison (although I must say that the Bose SoundDock does look better than the Apple iPod Hi-Fi, and it's cheaper).
Half of that AOL article is about the failure ofthe AOL/Time Warner merger, a subject which could fill many libraries.