Installing a LaTeX package

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Let’s say you want to create a A0 poster with LaTeX. You find an example on the internet that starts like this: 

\documentclass[final]{beamer}
\usepackage[orientation=landscape,size=a0,scale=1]{beamerposter}
\usepackage{lipsum} % lorem ipsum

You download the example ‘example.tex’, run pdflatex on it and it fails like this:

me@mycomputer: pdflatex example.tex
This is pdfTeX, Version 3.1415926-2.3-1.40.12 (TeX Live 2011)
 restricted \write18 enabled.
entering extended mode
(./example.tex
LaTeX2e <2011/06/27>
Babel  and hyphenation patterns for english, dumylang, nohyphenation, lo
aded.
(/usr/share/texlive/texmf-dist/tex/latex/beamer/beamer.cls

[...]

! LaTeX Error: File `beamerposter.sty' not found.

Type X to quit or  to proceed,
or enter new name. (Default extension: sty)

Enter file name:

This means, that this particular LaTeX package ‘beamerposter’ is not installed on your machine. Bad luck.

What to do if you have admin permissions

On linux, open your favourite package manager (e.g., Synaptic), type the name of the LaTeX package (in this case ‘beamerposter’). If the result shows a linux package like ‘texlive-latex-extra’ install it and be happy.

What to do if you do not have admin permissions

1. Download the package

Go to CTAN. Search for the missing package name and click on the best result. In the beamerposter case, you will end up here. To get to a page where you can actually download the package, you need to follow the link listed under CTAN path in the box at the bottom of the page. Click on ‘Download’ and save the ‘beamerposter.zip’ somewhere on your computer.

We will also assume that the second package, ‘lipsum’, is also missing, you would find it on CTAN here.

2. Extract the package to the correct location

The READMEs of LaTeX package usually contain "Put it in your tex folder" or "Put it somewhere where LaTeX can find it" (if they contain anything on installation at all). What this actually means is, that there are several possibilities. LaTeX searches for sources in a few directories, depending on your system and LaTeX distribution. Some examples for linux and texlive are:

/usr/share/texmf/
/usr/share/texlive/texmf/
/usr/local/share/texmf/tex/latex/
~/texmf/

If you don’t have admin permissions, the easiest is to create a folder ‘texmf’ in your home directory (~). You will need in this folder a subfolder ‘tex’, and then ‘latex’. So in total you should have:

~
   |- texmf/
      |- tex
         |- latex

In this folder, i.e., ~/texmf/tex/latex/, you can put any style files and latex will find them. It is advisable to create separate folders for separate packages, so we will extract the ‘beamerposter.zip’ that we downloaded into the folder ~/texmf/tex/latex/beamerposter/ and ‘lipsum.zip’ into the folder ~/texmf/tex/latex/lipsum/. This is what the folder looks like now:

~
   |- texmf/
      |- tex
         |- latex
            |- beamerposter
               |- beamerposter.pdf
               |- beamerposter.sty
               |- beamerposter.tex
               |- example.tex
               |- README
            |- lipsum
               |- lipsum.dtx
               |- lipsum.ins
               |- lipsum.pdf
               |- README

As you can see, we now have a ‘beamerposter.sty’. So if this were the only package we needed, we could skip step 3. Unfortunately we are still missing ‘lipsum.sty’, so this is what step 3 is about.

3. Create a style file

As we see, there is no style file ‘lipsum.sty’. There is only a ‘lipsum.ins’ and a ‘lipsum.dtx’ file. The .dtx file is only to create the documentation and we can ignore it here. To create the style file, run latex (latex, not pdflatex!) on ‘lipsum.ins’:

me@mycomputer: latex lipsum.ins

The result should look like this:

~
   |- texmf/
      |- tex
         |- latex
            |- beamerposter
               |- ...
            |- lipsum
               |- lipsum.dtx
               |- lipsum.ins
               |- lipsum.log
               |- lipsum.pdf
               |- lipsum.sty
               |- README

4. Try pdflatex again

And it should work (unless of course a different package is missing…).

Updating the Database

If you install fonts and in some other cases you need to update the LaTeX package database. On linux/texlive this is done with ‘texhash’: 

me@mycomputer: texhash

More

This works for regular LaTeX packages. Bibtex packages go to texmf/bibtex. If there are fonts involved, you will need to put them in texmf/fonts and it might get tricky.

LaTeX at Wikibooks

Typesetting text in math mode

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In information retrieval and text classification, tf-idf plays a big role. Read the Wikipedia article to learn what it is about, here I want to deal with the problem of typesetting the formula in LaTeX.

The formula is log-weighted term frequency tf times inverse document frequency idf, if we naivly write this down, we arrive at this:

tf-idf_{t,d} = (1 +\log tf_{t,d}) \cdot \log \frac{N}{df_t}

When you look at the LaTeX output, you will see that several things go wrong. In math mode, LaTeX interprets two letters next to each other as a product of two variables. So the name tf becomes the mathematical expression “t times f” and is typeset accordingly. Also, in case of tf-idf, the name contains a hyphen. In math mode a hyphen between two expression is interpreted as a minus sign. So this is definitely not what we want.

How do we solve the problem? What we want is that this part is interpreted as normal text. One possibility to add text to equations is the command \mbox{} (another is the command \text{} which requires the amsmath package). So this is it:

\mbox{tf-idf}_{t,d} = (1 +\log \mbox{tf}_{t,d}) \cdot \log \frac{N}{\mbox{df}_t}

Which process has an open handle on my file x (fuser, lsof or Process Explorer)?

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Here’s how to find out if a file is locked because of another process that still has an open file handle.

On Linux/Unix just use: fuser or lsof

lsof | grep
fuser -v

On Windows the Sysinternals Process Explorer is a great answer to this (and many other questions):

Just Ctrl+F and enter the name or part of it and search

Stanford Tokenizer options for MATE Parser

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These are the options I use for the Stanford tokenizer to preprocess my data for parsing with the MATE Parser:

normalizeParentheses=false,
normalizeOtherBrackets=false,
untokenizable=allKeep,
escapeForwardSlashAsterisk=false

This is the explanation of the options from the documentation:

  • normalizeParentheses: Whether to map round parentheses to -LRB-, -RRB-, as in the Penn Treebank
  • normalizeOtherBrackets: Whether to map other common bracket characters to -LCB-, -LRB-, -RCB-, -RRB-, roughly as in the Penn Treebank
  • untokenizable: What to do with untokenizable characters (ones not known to the tokenizer). Six options combining whether to log a warning for none, the first, or all, and whether to delete them or to include them as single character tokens in the output: noneDelete, firstDelete, allDelete, noneKeep, firstKeep, allKeep. The default is “firstDelete”.
  • escapeForwardSlashAsterisk: Whether to put a backslash escape in front of / and * as the old PTB3 WSJ does for some reason (something to do with Lisp readers??).

Backup slides in LaTeX beamer

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Sometimes you have a LaTeX beamer presentation and want to have some "backup" slides that you may show if the audience is really interested in this detail, but otherwise not. There is a simple solution for that, the package appendixnumberbeamer.

You need to load the package in the preamble:

\usepackage{appendixnumberbeamer}

Then you just need to use "appendix" before the slides you want to have as backup:

\begin{frame}
Thank you for your attention!
\end{frame}

\appendix
% start backup slides here

\begin{frame}
\frametitle{Detailed Results of User Study}
...
\end{frame}

Remember to run pdflatex twice for the changes to take effect!

The slides in the appendix will not count towards the total slide number that is displayed for the normal slides. Backup slides will have their own slide numbers and total slide numbers counted anew from the start of the appendix. Very handy!

You can organize your backup slides in sections, these section will not appear in the table of content. If you use a beamer template with navigation (miniframes like in Szeged, or split like in Malmoe), the backup slides will not appear in the navigation. A cool thing is that on the backup slides, the navigation will show the structure of the backup slides, so you can easily change to the slide you want. A disadvantage is of course that everybody will see that you have more backup slides than actual slides 😉

Change the encoding of a file

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My favourite topic is "encoding" (of course that was sarcasm). So my first post is about how to change the encoding of some text file from Latin-1 to UTF-8 on command line:

iconv -f latin1 -t utf8 source_file > target_file

Of course we need to know what encoding the file is in… which may be a topic for some future post.

Hello world!

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hro: Welcome to our new blog. We’ll use this site to dump anything too useful to trash but too hard to remember at our next cup of coffee…

swk: Where do you want to attach the PP “at our next cup”? “Dump it at our next cup” or “hard to remember at our next cup”?

hro: Arrgghh, I’m writing with a computational linguist. Ok then, how do you want to phrase it then?

swk: pfff… “We’ll use this site to dump anything too useful to trash, but too hard to remember should we need it again.”