Memo to self: I installed RMySQL using
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.
When you start using R, it can be confusing that if you assign something to an object you do not get visual feedback:
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.
For the record. I got an error running hyperref:
Paragraph ended before \Hy@setref@link was complete
This was due to having a regulare closing parenthesis directly after the curly bracket that closed a \ref, like this: (see section \ref{section-1}). Putting in a space between the closing curly bracket and parenthesis solved the problem: ... section-1} )
I don’t know the first thing about programming, but sometimes you see something and appreciate how elegant it is. This small solution from r-help is a good example. Someone wanted, given a vector c('p','p','t','t','t','p','k','t') to produce NA NA 1 2 3
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 want to set my signature when mailing to the r-help mailing list to contain information about the R version I have currently installed. Creating a bash script that directly echoes the several lines that I want to have in my signature and executing that in the muttrc using backticks gives a “broken pipe” error.
One solution (I’m sure there are others, maybe better ones) is to make the shell script create a temporary signature file and echo the path to that file, then execute the shell script using backticks.
Shell script (don’t forget to chmod 744):
#!/bin/bash thesigfile=~/.mutt/rsig echo "Marianne Promberger PhD, King's College London http://promberger.info" > $thesigfile R --version | head -n 1 >> $thesigfile cat /etc/issue | head -n 1 | cut -d " " -f 1-2 >> $thesigfile echo $thesigfile
muttrc:
send-hook '~t r-help' 'set signature=`~/.mutt/signature_r-help`'