How to split the bibliography alphabetically?

Question

I am using biblatex (with biber) and I am currently writing a book class document. I will have a long bibliography at the end of the document.

Inside this bibliography I would like to have alphabetical sections (A, B, C, ...). The purpose is to help someone who is looking for a reference; he can visualize that he is inside G section (for example). This is the kind of layout that dictionaries have.

Here is an visual attempt to show what I want to achieve:

**A** (Big "A" with a size of a section)

Author1 , ...
  --, ...
  --, ...
Author2, ...
.
.
.

**B** (Big "B")

Bauthor1, ...
  --, ...
Bauthor2, ...
  --, ...
.
. 
.

Of course, I can add keywords to my .bib file and say to BibLaTeX to print all references with keywords "A" inside a section "A". But it sounds stupid to add keywords just for alphabetical section sorting.

Here is a MWE:

\documentclass[12pt,twoside,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{graphicx} 
\usepackage{lmodern}
\usepackage{xspace}
\usepackage[style=authoryear-comp,hyperref,backend=biber,isbn=false,doi=false,url=false]{biblatex}
\bibliography{bib}
\title{}
\usepackage[francais]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}

\begin{document}

\nocite* 
\printbibliography
\end{document}

.bib file:

@InBook{arwez_title_2000,
  author =   {Paul Arwez},
  title =    {Title},
  chapter =      {Chapter},
  publisher =    {Publisher},
  year =     2000}

@Book{arwez_book_2013,
  author =   {Paul Arwez},
  title =    {Book},
  publisher =    {Publisher},
  year =     2013}

@Book{barwez_book_2013,
  author =   {Paul Barwez},
  title =    {Book},
  publisher =    {Publisher},
  year =     2013}

@Book{carwez_book_2013,
  author =   {Paul Carwez},
  title =    {Book},
  publisher =    {Publisher},
  year =     2013}

@Article{carwez_artic_1873,
  author =   {Paul Carwez},
  title =    {Article},
  journal =      {Journal},
  year =     1876}

.bbl file:

% $ biblatex auxiliary file $
% $ biblatex bbl format version 2.2 $
% Do not modify the above lines!
%
% This is an auxiliary file used by the 'biblatex' package.
% This file may safely be deleted. It will be recreated by
% biber as required.
%
\begingroup
\makeatletter
\@ifundefined{[email protected]}
  {\@latex@error
     {Missing 'biblatex' package}
     {The bibliography requires the 'biblatex' package.}
      \aftergroup\endinput}
  {}
\endgroup


\refsection{0}
  \sortlist{entry}{nyt}
    \entry{arwez_title_2000}{inbook}{}
      \name{labelname}{1}{}{%
        {{uniquename=0,hash=378583d49d9a8ada29208d6cb5267d5f}{Arwez}{A\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \name{author}{1}{}{%
        {{uniquename=0,hash=378583d49d9a8ada29208d6cb5267d5f}{Arwez}{A\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \list{publisher}{1}{%
        {Publisher}%
      }
      \strng{namehash}{378583d49d9a8ada29208d6cb5267d5f}
      \strng{fullhash}{378583d49d9a8ada29208d6cb5267d5f}
      \field{sortinit}{A}
      \field{labelyear}{2000}
      \field{labeltitle}{Title}
      \field{chapter}{Chapter}
      \field{title}{Title}
      \field{year}{2000}
    \endentry
    \entry{arwez_book_2013}{book}{}
      \name{labelname}{1}{}{%
        {{uniquename=0,hash=378583d49d9a8ada29208d6cb5267d5f}{Arwez}{A\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \name{author}{1}{}{%
        {{uniquename=0,hash=378583d49d9a8ada29208d6cb5267d5f}{Arwez}{A\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \list{publisher}{1}{%
        {Publisher}%
      }
      \strng{namehash}{378583d49d9a8ada29208d6cb5267d5f}
      \strng{fullhash}{378583d49d9a8ada29208d6cb5267d5f}
      \field{sortinit}{A}
      \field{labelyear}{2013}
      \field{labeltitle}{Book}
      \field{title}{Book}
      \field{year}{2013}
    \endentry
    \entry{barwez_book_2013}{book}{}
      \name{labelname}{1}{}{%
        {{uniquename=0,hash=d0455efa6586ff2338c954fc0860f0d2}{Barwez}{B\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \name{author}{1}{}{%
        {{uniquename=0,hash=d0455efa6586ff2338c954fc0860f0d2}{Barwez}{B\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \list{publisher}{1}{%
        {Publisher}%
      }
      \strng{namehash}{d0455efa6586ff2338c954fc0860f0d2}
      \strng{fullhash}{d0455efa6586ff2338c954fc0860f0d2}
      \field{sortinit}{B}
      \field{labelyear}{2013}
      \field{labeltitle}{Book}
      \field{title}{Book}
      \field{year}{2013}
    \endentry
    \entry{carwez_artic_1873}{article}{}
      \name{labelname}{1}{}{%
        {{uniquename=0,hash=baa123e8e737243bb6575c9b2955a321}{Carwez}{C\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \name{author}{1}{}{%
        {{uniquename=0,hash=baa123e8e737243bb6575c9b2955a321}{Carwez}{C\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \strng{namehash}{baa123e8e737243bb6575c9b2955a321}
      \strng{fullhash}{baa123e8e737243bb6575c9b2955a321}
      \field{sortinit}{C}
      \field{labelyear}{1876}
      \field{labeltitle}{Article}
      \field{journaltitle}{Journal}
      \field{title}{Article}
      \field{year}{1876}
    \endentry
    \entry{carwez_book_2013}{book}{}
      \name{labelname}{1}{}{%
        {{uniquename=0,hash=baa123e8e737243bb6575c9b2955a321}{Carwez}{C\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \name{author}{1}{}{%
        {{uniquename=0,hash=baa123e8e737243bb6575c9b2955a321}{Carwez}{C\bibinitperiod}{Paul}{P\bibinitperiod}{}{}{}{}}%
      }
      \list{publisher}{1}{%
        {Publisher}%
      }
      \strng{namehash}{baa123e8e737243bb6575c9b2955a321}
      \strng{fullhash}{baa123e8e737243bb6575c9b2955a321}
      \field{sortinit}{C}
      \field{labelyear}{2013}
      \field{labeltitle}{Book}
      \field{title}{Book}
      \field{year}{2013}
    \endentry
  \endsortlist
\endrefsection
\endinput

Answer 1

You can create a category for each letter in the alphabet and, with \AtDataInput, add entries to each category on the basis of the sortinit field.

\documentclass{book}
\usepackage[style=alphabetic]{biblatex}

\addbibresource{biblatex-examples.bib}
\nocite{angenendt,bertram,doody,gillies}

% user-level test for skipbib enabled (e.g. related entry matuz:doody)
\makeatletter
\def\ifskipbib{\iftoggle{blx@skipbib}}
\makeatother

\def\initlist{}
\forcsvlist{\listadd\initlist}{A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z}
\forlistloop{\DeclareBibliographyCategory}{\initlist}
\renewcommand*{\do}[1]{\defbibheading{#1}{\section*{#1}}}
\dolistloop{\initlist}
\AtDataInput{\ifskipbib{}{\addtocategory{\thefield{sortinit}}{\thefield{entrykey}}}}

\begin{document}
\printbibheading
\bibbycategory
\end{document}

Note that we need to access some internals to avoid entries that are skipped in the bibliography. I keep forgetting to make these toggle values available to the user, but we'll get around to it soon.

Answer 2

Here a hack of the internal bibitem:

\documentclass[]{scrartcl}

\usepackage[style=alphabetic]{biblatex}
\makeatletter
\def\blx@head@tempa{0}
\def\blx@bibitem#1{%
  \blx@ifdata{#1}
    {\begingroup
     \blx@getdata{#1}%
     \blx@imc@iffieldequals{sortinit}\blx@head@tempa{}{\item[]\textbf{\thefield{sortinit}}}%
       \global\let\blx@head@tempa\abx@field@sortinit%
     \blx@bibcheck
       \global\let\blx@noitem\@empty
     \iftoggle{blx@skipentry}{}{%
       \blx@setoptions@type\abx@field@entrytype
       \blx@setoptions@entry
       \blx@thelabelnumber
       \blx@addprefixnumber
       \addtocounter{instcount}\@ne
       \csuse{blx@item@\blx@theenv}\relax
       \blx@initsep
       \blx@namesep
       \csuse{blx@hook@bibitem}%
       \blx@execute
       \blx@initunit
       \blx@anchor
       \blx@beglangbib
       \bibsentence
       \blx@pagetracker
       \blx@driver\abx@field@entrytype
       \blx@postpunct
       \blx@endlangbib}%
     \endgroup}
    {}}
\makeatother
\addbibresource{biblatex-examples.bib}
\begin{document}
\nocite{*}
\printbibliography
\end{document}

Answer 3

Although the marking of alphabetical sections with "heading letters" is sometimes used for indexes, I have never encountered such letters in bibliographies. I suggest to only add extra spacing between alphabetical sections; with biblatex, this can be done by simply setting the \bibinitsep length to a positive value.

\documentclass{book}

\usepackage[style=authoryear]{biblatex}

\setlength{\bibinitsep}{\baselineskip}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@misc{A01,
  author = {Author, A.},
  year = {2001},
  title = {Alpha},
}
@misc{A02,
  author = {Author, A.},
  year = {2002},
  title = {And now for something completely different},
}
@misc{B02,
  author = {Buthor, B.},
  year = {2002},
  title = {Bravo},
}
\end{filecontents}

\addbibresource{\jobname.bib}

\nocite{*}

\begin{document}

\printbibliography

\end{document}

Answer 4

As biblatex is able to insert a space (\bibinitsep) between this entries, it should also be possible to enter text at this places. The main problem is that we are in a list and so getting the correct spacing and identation is a bit problematic:

\documentclass[12pt,twoside,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{xspace}
\usepackage[style=authoryear-comp,hyperref,backend=biber,isbn=false,doi=false,url=false]{biblatex}
\addbibresource{bib.bib}
\title{}
\usepackage[francais]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}

\makeatletter

\newcommand\bibsection{\@startsection {section}{1}{-\leftmargin}%
                                   {-3.5ex \@plus -1ex \@minus -.2ex}%
                                   {2.3ex \@plus.2ex}%
                                   {\normalfont\Large\bfseries}}

\bibinitsep=1pt %to trigger blx@initsep
\def\blx@initsep{%
  \blx@imc@iffieldundef{sortinit}
    {}
    {\ifnum\c@instcount>\@ne
       \blx@imc@iffieldequals{sortinit}\blx@previnit
         {}
         {\bibsection*{\printfield{sortinit}}\item}%instead of \addvspace
     \fi
     \global\let\blx@previnit\abx@field@sortinit}}
\makeatother
\begin{document}

\nocite*
\printbibliography
\end{document}

Answer 5

Disclaimer: This is a work-around, not a solution.

You could use biblatex's ability to filter bibliographic entries according to the keywords field to do this. All you need to do is add keywords = {<letter>} to every bibliographic entry, and \printbibliography[keyword=<letter>] will do the rest for you:

I had to use my bibliography because yours wouldn't display correctly (not sure why). Also, \bibliography{<file>} is deprecated now, so I replaced it with \addbibresource{<file>.ext}. See the example below.

\documentclass[12pt,twoside,a4paper]{book}
\begin{filecontents}{bib.bib}
@Article{a:agrawal:2001:01,
  title         = {Phenotypic Plasticity in the Interactions and Evolution of Species},
  author        = {Agrawal, Anurag A.},
  journal       = {Science},
  year          = {2001},
  month         = oct,
  volume        = {294},
  number        = {5541},
  pages         = {321--326},
  doi           = {10.1126/science.1060701},
  url           = {http://dx.doi.org/10.1126/science.1060701},
  keywords      = {A},
}

@Article{a:auld:2010:01,
  title         = {Re-evaluating the Costs and Limits of Adaptive Phenotypic Plasticity},
  author        = {Auld, Josh R. and Agrawal, Anurag A. and Relyea, Rick A.},
  journal       = {Proceedings of the Royal Society B: Biological Sciences},
  year          = {2010},
  month         = feb,
  volume        = {277},
  number        = {1681},
  pages         = {503--511},
  doi           = {10.1098/rspb.2009.1355},
  url           = {http://dx.doi.org/10.1098/rspb.2009.1355},
  keywords      = {A},
}

@Article{a:brown:2013:01,
  title         = {What Evolvability Really Is},
  author        = {Brown, Rachael L.},
  journal       = {The British Journal for the Philosophy of Science},
  year          = {2013},
  month         = aug,
  doi           = {10.1093/bjps/axt014},
  url           = {http://dx.doi.org/10.1093/bjps/axt014},
  keywords      = {B},
}

@Article{a:clune:2013:01,
  title         = {The Evolutionary Origins of Modularity},
  author        = {Clune, Jeff and Mouret, Jean-Baptiste and Lipson, Hod},
  journal       = {Proceedings of the Royal Society B: Biological Sciences},
  year          = {2013},
  month         = mar,
  volume        = {280},
  number        = {1755},
  doi           = {10.1098/rspb.2012.2863},
  url           = {http://dx.doi.org/10.1098/rspb.2012.2863},
  keywords      = {C},
}

@Article{a:dias:2013:01,
  title         = {Parental Olfactory Experience Influences Behavior and Neural Structure in Subsequent Generations},
  author        = {Dias, Brian G. and Ressler, Kerry J.},
  journal       = {Nature Neuroscience},
  publisher     = {Nature Publishing Group},
  year          = {2013},
  month         = dec,
  volume        = {},
  number        = {},
  pages         = {1546--1726},
  doi           = {10.1038/nn.3594},
  url           = {http://dx.doi.org/10.1038/nn.3594},
  keywords      = {D},
}
\end{filecontents}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{xspace}
\usepackage[style=authoryear-comp,hyperref,backend=biber,isbn=false,doi=false,url=false]{biblatex}
\addbibresource{bib.bib}
\title{}
\usepackage[francais]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}

\begin{document}

\nocite{*}
% \printbibliography
\printbibliography[keyword=A,title={A},heading=subbibliography]
\printbibliography[keyword=B,title={B},heading=subbibliography]
\printbibliography[keyword=C,title={C},heading=subbibliography]
\printbibliography[keyword=D,title={D},heading=subbibliography]
\end{document}

Answer 6

I give a bibtex solution, in case someone looks for it.

Well, you should be able to use the following. The idea is that we (1) assume the optional argument is always given, and (2) assume that the first token/letter of the optional argument is the right thing.

File test.tex:

\documentclass{article}

\begin{document}

\makeatletter
\let\x@bibitem\bibitem% store original \bibitem
\def\x@getfirst#1#2\endgetfirst{#1}% macro that returns the first letter/token of its argument
\def\x@bibalph{}% previous first letter, initiated to nothing
\def\bibitem[#1]{% new bibitem
  \edef\x@bibalphtest{\x@getfirst#1\endgetfirst}% get the new first letter
  \ifx\x@bibalphtest\x@bibalph\else % if the first letter changed
    \let\x@bibalph\x@bibalphtest% update
    \subsection*{\x@bibalph}% and make the \subsection
  \fi
  \x@bibitem[#1]% start the \bibitem itself
}
\makeatother

\bibliographystyle{amsalpha}
\bibliography{test}

\end{document}

File test.bbl:

\begin{thebibliography}{ABC06}

\bibitem[Aut00]{author_00}
Author, 2000.

\bibitem[ABC06]{author_buthor_cuthor_2005}
Author, Buthor, Cuthor, 2005.

\bibitem[But02]{buthor_2002}
Buthor, 2002.

\end{thebibliography}