invalid argument to unary operator

It happened when I was specifying custom labels with scale_y_continuous but it turns out this was irrelevant and it hinged on a line break. It turnsout (at least when stepping through the code with ESS in Emacs using C-c C-c, bound to ess-eval-function-or-paragraph-and-step, you need to have the + of tying different ggplot bits together on the end of the preceding line.

This won’t work:

ggplot(longdata, aes(x=x, y = y))
+ geom_jitter(alpha = 0.6)

This will:

ggplot(longdata, aes(x=x, y = y)) +
geom_jitter(alpha = 0.6)

(Or, put it all on one line).

If you show us your data/code/output as has been requested, then we may be able to tell which it is. Without that information you are expecting either R or the members of the list to read your mind. I keep making notes to my future self to use the timetravel package (not written yet, that’s why I need my future self to use it) to send a copy of the esp package (also not written yet) back in time to me so I can use it for situations like this. But so far that has not worked (maybe my future self is even more lazy than my present self, or my near future self does something to offend my far future self enough that he is unwilling to do this small favor for my current past self, darn, either way means I should probably do better on the diet/exercise).

Time for lunch.

sudo aptitude install r-cran-rmysql

because when I used

install.packages("RMySQL")

it asked my to specify the MySQL libraries and headers and whatnot and don’t know where they are.

x <- rep(1:3,5)

You have to then type x to see it:

> x
 [1] 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

You can exploit this fact for doing a quick-and-dirty lottery. Assume you have a file with email addresses, one per line, called "entries.txt". First, read them and assign them to an object:

entries <- readLines("entries.txt")

Next, create an index of numbers of the same length but in random order:

index <- sample(1:length(entries),length(entries))

Note that you don't see it unless you type index. Combine index and emails in a dataframe (also not directly visible):

dat <- data.frame(cbind(index,entries))

Now, go to random.org and draw a number from the index. Type dat to reveal who you drew. This method makes it a bit more "blind" and a bit less likely that you'll cheat.

test <- c('p','p','t','t','t','p','k','t')
v <- cumsum(ind <- test == 't')
v[!ind] <- NA

I didn't know you could assign something to an object and use it at the same time. Very neat. So if you wanted this all at once, you could also do:

v <- ifelse(cumsum(ind <- test=='t')==0,NA,cumsum(ind))

or

ifelse((v <- cumsum(test=='t'))==0,NA,v)

Maybe Dimitris' solution is in fact preferred for R, using indexing instead of if/ else, but I don't know enough about R to know whether that makes a difference.

I have a data frame “test”:

test<-data.frame(x=c(1,2,3,4,5,6,7,8),y=c(2,3,4,5,6,7,8,9),total=c(7,7,8,8,9,9,10,10))
test

I have a vector "needed":

needed<-c(7,9)
needed

I need the result to look like this:

1 2 7
2 3 7
5 6 9
6 7 9

When I do the following:

result<-test[test["total"]==needed,]
result

I only get unique rows that have 7 or 9 in "total":

1 2 7
6 7 9

[...]

The solution is to use %in% instead:

test[test$total %in% needed,]

A quick aside: note that you don't select the column "total" by using test["total"], instead, you need to index correctly and use test[,"total"], or, more succinctly, use test$total for dataframes. Check also identical(test["total"],test$total) and identical(test[,"total"],test$total).

Why doesn't == work here? It works just fine if you want to find all rows where the column total equals 7:

test[test$total == 7,]

The trick is that to R, test$total, needed and 7 are all vectors. == compares them element by element. Since 7 and needed are shorter than test$total, they are recycled as often as needed to give the same length as test$total. (Note, by the way, that you can of course directly look at the logical index by typing: test$total==needed.) So what R is doing is comparing this:

> test$total
[1]  7  7  8  8  9  9 10 10

to this:

> rep(needed,length.out=length(test$total))
[1] 7 9 7 9 7 9 7 9

The two vectors just happen to coincide at test$total[1] and test$total[6]. The recycling is of course no problem when you look for matches with a single number, because:

> rep(7,length.out=length(test$total))
[1] 7 7 7 7 7 7 7 7

will do just fine.

To get the help text on %in% by the way, you need to quote it:

?"%in%"

install.packages("RGoogleDocs", repos = "http://www.omegahat.org/R")

RGoogleDocs requires RCurl, and will automatically install it. However, for me, this resulted in the error message:

checking for curl-config... no
Cannot find curl-config

and RGoogleDocs was not installed. This is in fact in the RCurl FAQ. The solution may differ for your system, but on Xubuntu Jaunty I needed to get:

sudo aptitude install libcurl4-gnutls-dev

This fixed the RCurl problem, but I installation of XML (also required, and also automatically installed when you install RGoogleDocs) failed with:

checking for xml2-config... no
Cannot find xml2-config
ERROR: configuration failed for package �XML�

You guessed it:

sudo aptitude install libxml2-dev

So here’s the whole thing for cut-and-paste:

sudo aptitude install libcurl4-gnutls-dev libxml2-dev

Then:

sudo R

Then, inside R:

install.packages("RGoogleDocs", repos = "http://www.omegahat.org/R")

Addendum

Just had to install RGoogleDocs again and had a different issue. It complained that it couldn’t get package bitops which seems to be a depenency for RCurl. First step (which I just learned):

install.packages("RGoogleDocs", repos = "http://www.omegahat.org/R", dependencies = TRUE)

was not sufficient in my case. Had to manually first

install.packages("bitops")

Addendum

Version 0.4.0, which you get from Omegahat, doesn’t work but throws an authentication failure when you try to load a spreadsheet.
Try version 0.4.1 (downloads a .tar.gz file). To install the file:

install.packages("~/downloads/RGoogleDocs_0.4-1.tar.gz",repos=NULL)

(of course, replace ~/downloads/ with the appropriate directory).
Doesn’t work for me (22/2/2011). I still get “unauthorized” when trying to access a document (I can access the list of documents just fine).

If you use R, you most likely want ESS (Emacs Speaks Statistics) for your GNU Emacs. If you use LaTeX, you will also want AucTeX.

I highly recommend you use Vincent Goulet’s modified Emacs version. As an additional benefit, it comes as a convenient self-installing .exe file.

Thanks Vincent!

p.s. To get LaTeX on Windows, you will want to get MiKTeX. MiKTeX is very nice and can auto-install missing packages on the fly when you want to use them in a document.