[R] converting numerical parts of factors into numeric vectors

[Jan.Schelling@hydro.com]

Try:

as.numeric(levels(x)[x])

However, this gives you a warning if you have any non-numerical levels as
mentioned in the help file for 'as.numeric'.

Jan


-------------------------
Jan Schelling
Norsk Hydro
Research Centre
N - 3907 Porsgrunn
NORWAY





From: wolters at ikp.uni-bonn.de on 2000-04-28 10:23 GMT



To:   r-help at stat.math.ethz.ch
cc:    (bcc: Jan Schelling/HRE/Hydro)

Subject:  [R] converting numerical parts of factors into numeric vectors



Dear list,

Problem:
Given a factor that contains both numerical values and category codes,
how can I extract the numerical values and store them in a numeric
vector while preserving the exact values? as.numeric() replaces the
numerical values by their factor levels. But since the values represent
an interval-scaled distance measure, this is not exactly what is called
for.

Current workaround: replace category codes by arbitrary numbers to be filtered
out later. In this case, negative numbers.

More elegant solution: ?

I checked CRAN, V&R, and the online help, but to no avail.

Thanks in advance for your help. (The problem is not urgent,
see "Current Workaround" ;)

Maria Wolters
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