From pengyu.ut at gmail.com  Fri Jan  1 00:27:50 2010
From: pengyu.ut at gmail.com (Peng Yu)
Date: Fri, 1 Jan 2010 17:27:50 +1800
Subject: [Rd] How x[, 'colname1'] is implemented?
In-Reply-To: <77EB52C6DD32BA4D87471DCD70C8D700024DD3D9@NA-PA-VBE03.na.tibco.com>
References: <366c6f340912311415qfd00d4codf366e1919ca8b5f@mail.gmail.com>
	<77EB52C6DD32BA4D87471DCD70C8D700024DD3D9@NA-PA-VBE03.na.tibco.com>
Message-ID: <366c6f340912311527u52d4c62bn151fc33d2fc502fb@mail.gmail.com>

I don't see where describes the implementation of '[]'.

For example, if x is a matrix or a data.frame, how the lookup of
'colname1' is x[, 'colname1'] executed. Does R perform a lookup in the
a hash of the colnames? Is the reference O(1) or O(n), where n is the
second dim of x?



[Rd] How x[, 'colname1'] is implemented?
Peng Yu