Error(s) in re-building vignettes:
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--- re-building ‘pavo-1-overview.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘pavo-1-overview.Rmd’

--- re-building ‘pavo-2-importing_processing.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Welcome to pavo 2! Take a look at the latest features (and update your bibliography) in our recent publication: Maia R., Gruson H., Endler J. A., White T. E. (2019) pavo 2: new tools for the spectral and spatial analysis of colour in R. Methods in Ecology and Evolution, 10, 1097-1107.
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
--- finished re-building ‘pavo-2-importing_processing.Rmd’

--- re-building ‘pavo-3-analysing.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Welcome to pavo 2! Take a look at the latest features (and update your bibliography) in our recent publication: Maia R., Gruson H., Endler J. A., White T. E. (2019) pavo 2: new tools for the spectral and spatial analysis of colour in R. Methods in Ecology and Evolution, 10, 1097-1107.
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Calculating noise-weighted Euclidean distances and noise-weighted luminance contrasts
Calculating noise-weighted Euclidean distances
Calculating noise-weighted Euclidean distances
Calculating noise-weighted Euclidean distances
Calculating noise-weighted Euclidean distances
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
wavelengths found in column 1
processing options applied:
Scaling spectra to a maximum value of 1
wavelengths found in column 1
processing options applied:
Scaling spectra to a total area of 1
processing options applied:
Scaling spectra to a minimum value of zero
wavelengths found in column 1
Calculating noise-weighted Euclidean distances and noise-weighted luminance contrasts
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
Using single set of coldists for all images.
Using single set of hsl values for all images.
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
wavelengths found in column 1
Calculating noise-weighted Euclidean distances
Warning in hook_png(before, options, envir, "pngquant", function(x) { :
  cannot find pngquant; please install and put it in PATH
One or more image matrices are not of class 'rimg'; attempting to coerce.
--- finished re-building ‘pavo-3-analysing.Rmd’

--- re-building ‘pavo-4-spectraldesc.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘pavo-4-spectraldesc.Rmd’

--- re-building ‘pavo-5-alphashapes.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Loading required namespace: rmarkdown
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Warning in normalizePath(f2) :
  path[1]="webshot514919ae7303.png": No such file or directory
Warning in file(con, "rb") :
  cannot open file 'webshot514919ae7303.png': No such file or directory
Quitting from lines 99-100 (pavo-5-alphashapes.Rmd) 
Error: processing vignette 'pavo-5-alphashapes.Rmd' failed with diagnostics:
cannot open the connection
--- failed re-building ‘pavo-5-alphashapes.Rmd’

SUMMARY: processing the following file failed:
  ‘pavo-5-alphashapes.Rmd’

Error: Vignette re-building failed.
Execution halted