Loading and Saving Frequency Spectra (zipfR)

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Description

read.spc loads frequency spectrum from .spc file

write.spc saves frequency spectrum object in .spc file

Usage

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Arguments

file

character string specifying the pathname of a disk file. Files with extension .gz will automatically be compressed/decompressed. See section "Format" for a description of the required file format

spc

a frequency spectrum, i.e.\ an object of class spc

Format

A TAB-delimited text file with column headers but no row names (suitable for reading with read.delim). The file must contain at least the following two columns:

m

frequency class m

Vm

number V_m of types in frequency class m (or expected class size E[V_m])

An optional column labelled VVm can be used to specify variances of expected class sizes (for a frequency spectrum derived from a LNRE model or by binomial interpolation).

These columns may appear in any order in the text file. All other columns will be silently ignored.

Details

If the filename file ends in the extension .gz, the disk file will automatically be decompressed (read.spc) and compressed (write.spc).

The .spc file format does not store the values of N, V and VV explicitly. Therefore, incomplete frequency spectra and expected spectra with variances cannot be fully reconstructed from disk files. Saving such frequency spectra (or loading a spectrum with variance data) will trigger corresponding warnings.

Value

read.spc returns an object of class spc (see the spc manpage for details)

See Also

See the spc manpage for details on spc objects. See read.tfl and read.vgc for import/export of other data structures.

Examples

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## Not run: 

## examples will not be run during package compilation
## since they would require accessing and writing to
## external files

## load Italian ultra- data
## and write corresponding spectrum to external text file
data(ItaUltra.spc)
write.spc(ItaUltra.spc,"ultra.spc")
## now ultra.spc is a text file with columns m and Vm

## we ready it back in
New.spc <- read.spc("ultra.spc")

## same spectrum as ItaUltra.spc, compare:
summary(New.spc)
summary(ItaUltra.spc)

## DON'T do the following, incomplete spectrum will not be
## restored properly!!!
zm <- lnre("zm",ItaUltra.spc) # estimate model
zm.spc <- lnre.spc(zm,N(zm)) # incomplete spectrum from model
write.spc(zm.spc,"var.spc") # warnings
bad.spc <- read.spc("/Users/baroni/Desktop/var.spc")
## latter is DIFFERENT from zm.spc!!!


## End(Not run)

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