hadley

29 ms·

301.
by hadley 16y ago
I'd be interested to learn how to add missing value support into an existing language. It's pervasive in R, so important for statistics, and it seems like it would be hard to patch onto an existing language.
302.
by hadley 16y ago
Vectors are not the same as 1d matrices/arrays because a vector does not have direction (i.e. it's not a row vector or a column vector, but will work as either depending on circumstance). > all.equal(1:10, matrix(1:10, ncol = 1))
303.
by hadley 16y ago
The semantics are fairly straightforward once you figure out the two main differences. Vectors, matrices and arrays are atomic/homogeneous objects, and only differ in their dimensionality. Vectors are 1d, matrices 2d, and arrays are 3d or h
304.
by hadley 16y ago
As well as paying your (meagre) salary, the funding usually also covers your tuition. So while $25k / year will cover your salary, it won't also cover your tuition.
305.
by hadley 16y ago
Yup, that's the apple design philosophy right there.
306.
by hadley 17y ago
I don't doubt the quality of your final model, I just think you might have found it easier to get there with a better method.
307.
by hadley 17y ago
Best of all you don't need to understand your problem domain?! This sounds like a recipe for disaster to me - how do you tell if your model is giving you nonsense or not?
308.
by hadley 17y ago
But why genetic algorithms? It seems odd to start with something so complex and so slow instead of starting with simple (eg. generalized linear models) and then work your way up if they are not good enough. I suspect there are many classica
309.
by hadley 17y ago
Sorry, that's rubbish. It's the "advanced" statistical techniques that help you discover and control for these problems. Sure, a lot of people apply them incorrectly and without really thinking about what they're doing and what their resu
310.
by hadley 17y ago
I'd second the recommendation. But avoid the manga guide to statistics - it's nowhere near as good.
311.
by hadley 17y ago
The mean is asymptotically normal and the standard deviation is asymptotically scaled chi-square; the distribution of every "meta"-statistic will be different.
312.
by hadley 17y ago
Except that the sampling distribution of the standard deviation is a scaled chi-square, not a normal. The central limit theorem is only for the mean, not any statistic that you might dream up. It's trivial to think of many that would not c
313.
by hadley 17y ago
The statistics are a little bit off - the Chi-squared isn't appropriate for the example he gives (sample size too small), although it would be fine in practice. What you really want in that situation is the exact binomial test.
314.
by hadley 17y ago
Why does doesn't suck = as good as excel?
315.
by hadley 17y ago
Good suggestion. Done.
316.
by hadley 17y ago
There are a few minor errors: * the explanation of 8.6 is wrong - it's cbind that's coercing all columns to a common type, not data.frame * 8.7 is a bad example of good R code - use column names not indices! * in 9 (and elsewhere) it's not
317.
by hadley 17y ago
Wow - fantastic!
318.
by hadley 17y ago
This is fantastic. I do a load of data scraping of the web and this (plus selector gadget) is going to make my life sooooo much easier.
319.
by hadley 17y ago
Small size of the community? In comparison to what?
320.
by hadley 17y ago
Most younger R programmers use _ for multiword names. Using . is generally not recommended as it is more commonly used to identify generic methods in the S3 object system.
321.
by hadley 17y ago
The rules are pretty simple. It works everywhere, except in a function call, where = is used for named parameters, not creating new variables.
322.
by hadley 17y ago
Thanks!
323.
by hadley 18y ago
This is a pretty old idea - see http://www.boingboing.net/2007/07/01/flip-text-upsidedown.ht... and http://pne.livejournal.com/398399.html
324.
by hadley 18y ago
Why is wealth correlated with test scores? Is it because wealth is correlated with intelligence (in this case presumably mediated through diet)? Or is it some other factor? What is this scholarship and how is it expected to help the studen
325.
by hadley 18y ago
polish != Polish: polish = "make shiny" Polish = something related to Poland I think you need a different name.
326.
by hadley 19y ago
There are two! One in the northern hemisphere and one in the southern.