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visa

This R package is to facilitate Vegetation Imaging Spectroscopy Analysis (VISA). For more details of this package, you can browseVignettes("visa").

Installation

install the released version from CRAN:

The very first version of visa (0.1.0) is on CRAN.

install.packages("visa")

You might encounter problem of package dependencies, such as some functions depend on ggplot2, ggpmisc. In such cases, you would have to install all the dependencies.

install the dev-version from GitHub:

The current version on GitHub is v1.0.0.

if (!require("devtools")) install.packages("devtools")
devtools::install_github("kang-yu/visa")
  • The v1.0.0 requires support for interactive plotting. Installation on Max OS may

cause error X11 library is missing.

Usage

library(visa)
data(NSpec.DF)
x <- NSpec.DF$N # nitrogen
S <- NSpec.DF$spectra[, seq(1, ncol(NSpec.DF$spectra), 10)] # resampled to 10 nm steps
cm.nsr(S, x, cm.plot = TRUE)

Bug report

You can report your issues of using visa here. Don't know how to report a bug? Check RStudio's Instructions on Writing Good Bug Reports.

You might find useful information by checking the issues reported by others.

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Version

Install

install.packages('visa')

Monthly Downloads

153

Version

1.0.0

License

GPL-3

Issues

Pull Requests

Stars

Forks

Maintainer

Kang Yu

Last Published

March 19th, 2025

Functions in visa (1.0.0)

ggplot.spectra

Create a new ggplot plot with a geom_line() layer from spectra data
spectra

Access the spectra data of 'SpectraLibrary'.
ggplot-method

Plot functions
nsr

Calculate Normalized Simple Ratio (NSR) index.
plt.2dcm

Create a ggplot Plot from a 2D Correlation Matrix
visa

visa: Vegetation Imaging Spectroscopy Analyzer
wavelength

Retrieve Wavelength Information from Spectra Objects
plt.3dcm_best

Create a 3D Slice Plot of Correlation Array
Spectra-class

Create a Spectra or SpectraLibrary
SpectraLibrary-class

Class 'SpectraLibrary'
SpectraMatrix-class

Class 'SpectraMatrix'
cm.nsr

Selecting the best 2-Band combinations for Normalized Simple Ratio (NSR)
NSpec.Lib

Example data in the Spectra/SpectraLibrary format.
SpectraDataframe-class

Class 'SpectraDataframe'
cm.rbd3

Calculate 3-Band Correlation Array for Spectral Data correlating with another variable x
cm.sr

Selecting the best 2-Band combinations for Simple Ratio (SR)
as.spectra.dataframe

Create a SpectraDataframe
sr

Calculate Simple Ratio (SR).
find.bestBands

Find Best Band Combinations
ndvi2

Calculate and plot a 2-band NDVI.
NSpec.DF

Example data in the Spectra.Dataframe format
ggplot.cm

Create a ggplot Plot from Correlation Coefficients (Deprecated)