besoin d'aide

In S-Plus, and presumably also in R, the execution of merge() with large 
data.frames is slow.  When speed becomes an issue, my colleagues use 
other language to handle this kind of operation with large data sets.

Hope this helps,
Spencer Graves

J'aimerais savoir si la fonction merge() est la seule disponible pour concatener des tableaux de donn?es?
Est-ce normal que l'ex?cution soit lente?

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La langue officielle de la liste est bien Anglais.
(The official language of the list is English.)

J'aimerais savoir si la fonction merge() est la seule disponible pour concatener des tableaux de donn?es?

Eh non, pour concatener il en a egalement rbind(), cbind() et pas mal
d'autres. 
(Oh no, there are also rbind() and cbind(), among others.)

Est-ce normal que l'ex?cution soit lente?

Ca depend.
(Depends)

Dirk
(Dirk)

Wishful thinking can dominate much of the work of a profession for a decade,
but not indefinitely.   -- Robert Shiller, on Efficient Markets models, 2002

? "concatener" ?  Transliterated, this suggests the function  rbind().
The function  merge()  does something very special.  If  rbind() will
do what you want, it might be much faster.

-  tom blackwell  -  u michigan medical school  -  ann arbor  -

J'aimerais savoir si la fonction merge() est la seule
disponible pour concatener des tableaux de données?
Est-ce normal que l'exécution soit lente?

The function merge() is like the "join" operation in relational data bases 
- it's much more powerful than mere concatenation (and thus often much 
slower, especially on large tables.)

To merely concatenate tables together, use rbind() (to concatenate by rows) 
or cbind() (to concatenate by columns).

If you do need the power of merge(), but it is too slow for your purposes 
you may be able to write a special-purpose function in R that does just 
only you need and much more quickly -- such is the nature of the S language 
-- it is very powerful, but the powerful general-purpose functions can 
often be quite slow in particular cases.

Hope this helps, and apologies if I have not completely understood your 
question.

-- Tony Plate

J'aimerais savoir si la fonction merge() est la seule disponible pour 
concatener des tableaux de donn?es?
Est-ce normal que l'ex?cution soit lente?

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https://www.stat.math.ethz.ch/mailman/listinfo/r-help

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