  The notion of community structure is particularly useful when analyzing
complex networks, because it provides an intermediate level, compared to the
more classic global (whole network) and local (node neighborhood) approaches.
The concept of community role of a node was derived from this base, in order to
describe the position of a node in a network depending on its connectivity at
the community level. However, the existing approaches are restricted to
undirected networks, use topological measures which do not consider all aspects
of community-related connectivity, and their role identification methods are
not generalizable to all networks. We tackle these limitations by generalizing
and extending the measures, and using an unsupervised approach to determine the
roles. We then illustrate the applicability of our method by analyzing a
Twitter network.We show how our modifications allow discovering the fact some
particular users called social capitalists occupy very specific roles in this
system.
  ---
  La notion de structure de communaut\'es est particuli\`erement utile pour
\'etudier les r\'eseaux complexes, car elle am\`ene un niveau d'analyse
interm\'ediaire, par opposition aux plus classiques niveaux local (voisinage
des noeuds) et global (r\'eseau entier). Le concept de r\^ole communautaire
permet de d\'ecrire le positionnement d'un noeud en fonction de sa
connectivit\'e communautaire. Cependant, les approches existantes sont
restreintes aux r\'eseaux non-orient\'es, utilisent des mesures topologiques ne
consid\'erant pas tous les aspects de la connectivit\'e communautaire, et des
m\'ethodes d'identification des r\^oles non-g\'en\'eralisables \`a tous les
r\'eseaux. Nous proposons de r\'esoudre ces probl\`emes en g\'en\'eralisant les
mesures existantes, et en utilisant une m\'ethode non-supervis\'ee pour
d\'eterminer les r\^oles. Nous illustrons l'int\'er\^et de notre m\'ethode en
l'appliquant au r\'eseau de Twitter. Nous montrons que nos modifications
mettent en \'evidence les r\^oles sp\'ecifiques d'utilisateurs particuliers du
r\'eseau, nomm\'es capitalistes sociaux.
