#' AVS -> SHE #' #' Converts from absolute vacuum scale (AVS) to SHE scale #' #' @param avs Potential in AVS scale #' #' @return potential in SHE scale (numeric) #' @export AVS2SHE <- function(avs) { .Deprecated("as.SHE") she <- -(4.5 + avs) return(she) } #' SHE -> AVS #' #' Converts from SHE scale to absolute vacuum (AVS) scale #' #' @param she Potential in SHE scale #' #' @return potential in AVS scale (numeric) #' @export SHE2AVS <- function(she) { .Deprecated("as.SHE") avs <- -(4.5 + she) return(avs) } #' Get standardised name of reference electrode #' #' Given a reference electrode label, this function returns its canonical name #' (as defined by this package). #' This function tries to match against as many variations as possible for each #' reference electrode. #' #' @param refname string #' #' @return the canonical name or empty string #' @export RefCanonicalName <- function(refname) { # scale names electrode.system <- list() electrode.system[["SHE"]] <- c("SHE", "Standard hydrogen", "Standard hydrogen electrode") electrode.system[["AgCl/Ag"]] <- c("AgCl/Ag", "Ag/AgCl", "AgCl", "Silver-Silver chloride", "Silver chloride", "SSC") # saturated silver-silver chloride is sometimes abbreviated SSC electrode.system[["Hg2Cl2/Hg"]] <- c("Hg2Cl2/Hg", "Hg/Hg2Cl2", "Hg2Cl2", "Calomel-Mercury", "Mercury-Calomel", "SCE") electrode.system[["AVS"]] <- c("AVS", "Vacuum", "Vacuum scale", "Absolute", "Absolute scale", "Absolute vacuum scale") electrode.system[["Li"]] <- c("Li", "Li/Li+", "Lithium") # to match the lowercase version, use tolower() # perhaps also replace hyphens and slashes with space? matches <- data.frame(electrode = names(electrode.system), m = rep(0, length(electrode.system)), stringsAsFactors = FALSE) # loop over electrode systems for (i in 1:length(electrode.system)) { # check for a match in any cell of this row, # also trying all lower-case and substituting symbols with spaces if (any(electrode.system[[i]] == refname) || any(tolower(electrode.system[[i]]) == refname) || any(gsub("[-/]", " ", electrode.system[[i]]) == refname)) { matches$m[i] <- 1 } } # if everything went as expected we should have just one match if (sum(matches$m) != 1) { # something wrong (should probably add warn/error here) # for now, just return empty string return("") } else { return(matches$electrode[which(matches$m == 1)]) } } #' Potentials as SHE #' #' This function just outputs a tidy dataframe with potential vs SHE for #' different scales, electrolytes, concentrations, and temperatures. #' Using data from literature. #' #' @return tidy dataframe with the following columns #' \tabular{ll}{ #' \code{electrode} \tab reference electrode \cr #' \code{electrolyte} \tab electrolyte \cr #' \code{conc.num} \tab concentration of electrolyte, mol/L \cr #' \code{conc.string} \tab concentration of electrolyte, as string, may also note temperature at which conc \cr #' \code{temp} \tab temperature / degrees Celsius \cr #' \code{SHE} \tab potential vs SHE / volt \cr #' \code{sid} \tab set id, just for housekeeping inside this function \cr #' \code{reference} \tab BibTeX reference \cr #' \code{dEdT} \tab temperature coefficient / volt/kelvin \cr #' } #' @export potentials.as.SHE <- function() { # scale name should be one of canonical (see RefCanonicalName) # follow the convention of "each row one observation" (at different temperatures) # all potentials vs SHE potentials <- as.data.frame(matrix(data = # electrode # electrolyte # conc/M # conc label # temp # pot vs SHE # set id # ref c("AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "10", "0.215", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "15", "0.212", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "20", "0.208", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "25", "0.205", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "30", "0.201", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "35", "0.197", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "3.5", "3.5M at 25C", "40", "0.193", "1", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "10", "0.214", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "15", "0.209", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "20", "0.204", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "25", "0.199", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "30", "0.194", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "35", "0.189", "2", "Sawyer1995", "AgCl/Ag", "KCl(aq)", "4.2", "saturated", "40", "0.184", "2", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "10", "0.336", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "15", "0.336", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "20", "0.336", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "25", "0.336", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "30", "0.335", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "35", "0.334", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "0.1", "0.1M at 25C", "40", "0.334", "3", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "1.0", "1.0M at 25C", "10", "0.287", "4", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "1.0", "1.0M at 25C", "20", "0.284", "4", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "1.0", "1.0M at 25C", "25", "0.283", "4", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "1.0", "1.0M at 25C", "30", "0.282", "4", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "1.0", "1.0M at 25C", "40", "0.278", "4", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "10", "0.256", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "15", "0.254", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "20", "0.252", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "25", "0.250", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "30", "0.248", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "35", "0.246", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "3.5", "3.5M at 25C", "40", "0.244", "5", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "10", "0.254", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "15", "0.251", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "20", "0.248", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "25", "0.244", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "30", "0.241", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "35", "0.238", "6", "Sawyer1995", "Hg2Cl2/Hg", "KCl(aq)", "4.2", "saturated", "40", "0.234", "6", "Sawyer1995", "AVS", "", "", "", "25", "-4.44", "7", "Trasatti1986"), ncol = 8, byrow = TRUE), stringsAsFactors = FALSE) colnames(potentials) <- c("electrode", "electrolyte", "conc.num", "conc.string", "temp", "SHE", "sid", "reference") # convert these columns to type numeric potentials[, c("conc.num", "temp", "SHE")] <- as.numeric(as.character(unlist(potentials[, c("conc.num", "temp", "SHE")]))) # make room for a dE/dT column potentials$dEdT <- as.numeric(NA) # calculate temperature coefficient (dE/dT) for each scale and concentration (ie. set id) for (s in 1:length(unique(potentials$sid))) { # sid column eas added to data just to make this calculation here easier subspot <- potentials[which(potentials$sid == unique(potentials$sid)[s]), ] # a linear fit will give us temperature coefficient as slope lm.subspot <- stats::lm(SHE ~ temp, data = subspot) potentials[which(potentials$sid == unique(potentials$sid)[s]), "dEdT"] <- lm.subspot$coefficients[2] } return(potentials) } #' Convert from electrochemical or electronic scale to SHE #' #' @param potential in the original scale, V or eV #' @param scale name of the original scale #' @param concentration of electrolyte in mol/L, or as the string "saturated" #' @param temperature of system in degrees Celsius #' @param as.SHE.data dataframe with dataset #' #' @return potential in SHE scale #' @export as.SHE <- function(potential, scale, concentration = "saturated", temperature = 25, as.SHE.data = potentials.as.SHE()) { # if the supplied temperature does not exist in the data, this function will attempt to interpolate # note that concentration has to match, no interpolation is attempted for conc if (RefCanonicalName(scale) == "") { warning("as.SHE(): Sorry, you have supplied an unrecognised electrode scale.") return(NA) } # there is the simple case of if (RefCanonicalName(scale) == "SHE") { warning("This function can only convert from scales other than SHE!") return(NA) } # AVS needs special consideration if (RefCanonicalName(scale) == "AVS") { # reset arg concentration concentration <- "" # second, since AVS scale goes in the opposite direction to the electrochemical scales # we will define our own function negifavs <- function(a, b) { a - b } } else { # we will define the same function differently for # the case we're not dealing with AVS negifavs <- function(a, b) { a + b } } if (is.character(concentration)) { # supplied concentration is character string subspot <- subset(subset(as.SHE.data, electrode == RefCanonicalName(scale)), conc.string == concentration) # if either "scale" or "concentration" are not found in the data, subspot will contain zero rows if (dim(subspot)[1] == 0) { warning("as.SHE(): Supplied scale or concentration does not exist in data. Returning NA.") return(NA) } # so far, we have # scale: checked! # concentration: checked! # only temperature remains to be handled # temperature value could happen to match a value in the data, or lie somewhere in between # note: we will not allow extrapolation if (!any(subspot$temp == temperature)) { # if sought temperature is not available in dataset, check that it falls inside if ((temperature < max(subspot$temp)) && (temperature > min(subspot$temp))) { # within dataset range, do linear interpolation lm.subspot <- stats::lm(SHE ~ temp, data = subspot) # interpolated temperature, calculated based on linear regression # (more accurate than simple linear interpolation with approx()) potinterp <- lm.subspot$coefficients[2] * temperature + lm.subspot$coefficients[1] ### CALC RETURN POTENTIAL return(negifavs(potinterp, potential)) } else { # outside dataset range, warning and return NA (we don't extrapolate) warning("as.SHE(): the temperature you requested falls outside data range.") return(NA) } } else { # requested temperature does exist in dataset ### CALC RETURN POTENTIAL return(negifavs(subset(subspot, temp == temperature)$SHE, potential)) } # outer-most if-else } else { # supplied concentration is numeric # note: all code inside this else is the same as inside the if, # just for the case of numeric concentration subspot <- subset(subset(as.SHE.data, electrode == RefCanonicalName(scale)), conc.num == concentration) # if either "scale" or "concentration" are not found in the data, subspot will contain zero rows if (dim(subspot)[1] == 0) { warning("as.SHE(): Supplied scale or concentration does not exist in data. Returning NA.") return(NA) } if (!any(subspot$temp == temperature)) { # if sought temperature is not available in dataset, check that it falls inside if ((temperature < max(subspot$temp)) && (temperature > min(subspot$temp))) { # within dataset range, do linear interpolation lm.subspot <- stats::lm(SHE ~ temp, data = subspot) # interpolated temperature, calculated based on linear regression # (more accurate than simple linear interpolation with approx()) potinterp <- lm.subspot$coefficients[2] * temperature + lm.subspot$coefficients[1] ### CALC RETURN POTENTIAL return(negifavs(potinterp, potential)) } else { # outside dataset range, warning and return NA (we don't extrapolate) warning("as.SHE(): the temperature you requested falls outside data range.") return(NA) } } else { # requested temperature does exist in dataset ### CALC RETURN POTENTIAL return(negifavs(subset(subspot, temp == temperature)$SHE, potential)) } } } #' ConvertRefPotEC #' #' This function does the heavy lifting. #' Converts from an electrochemical reference scale into another. #' SHE: standard hydrogen electrode #' Ag/AgCl: silver silver-chloride electrode (3M KCl) #' SCE: saturated calomel electrode #' #' @param argpotential potential (numeric) #' @param argrefscale input reference scale (character string) #' @param valuerefscale output reference scale (character string) #' #' @return potential in output reference scale (numeric) ConvertRefPotEC <- function(argpotential, argrefscale, valuerefscale) { .Deprecated("as.SHE") ##### Add more reference electrodes here >> refpotatSHEzero <- c( 0, -0.21, -0.24, 3) refrownames <- c( "SHE", "Ag/AgCl", "SCE", "Li/Li+") refcolnames <- c("SHE0", "AgCl0", "SCE0", "Li0") ##### Add more reference electrodes here << # SHE0 <- data.frame(matrix(refpotatSHEzero, ncol = length(refpotatSHEzero), byrow = T)) refpotmtx <- matrix(NA, length(SHE0), length(SHE0)) refpotmtx[,1] <- matrix(as.matrix(SHE0), ncol = 1, byrow = T) for (c in 2:length(SHE0)) { # loop over columns (except the first) for (r in 1:length(SHE0)) { # loop over rows refpotmtx[r, c] <- refpotmtx[r, 1] - refpotmtx[c, 1] } } refpotdf <- as.data.frame(refpotmtx) names(refpotdf) <- refcolnames row.names(refpotdf) <- refrownames ## So far we have made a matrix of all the possible combinations, ## given the vector refpotatSHEzero. The matrix is not strictly necessary, ## but it may prove useful later. It does. # # Match argrefscale to the refrownames argmatch <- match(argrefscale, refrownames, nomatch = 0) # Match valuerefscale to the refrownames valuematch <- match(valuerefscale, refrownames, nomatch = 0) # We simply assume that the match was well-behaved valuepotential <- argpotential + refpotdf[valuematch, argmatch] # Check that arg and value electrodes are within bounds for a match if (argmatch == 0 || valuematch == 0) { # No match # Perform suitable action message("Arg out of bounds in call to ConvertRefPot") valuepotential <- NA } return(valuepotential) } #' Convert from one electrochemical scale to another #' #' @param argpotential potential (numeric) #' @param argrefscale input reference scale (char string) #' @param valuerefscale output reference scale (char string) #' #' @return potential in output reference scale (numeric) #' @export ConvertRefPot <- function(argpotential, argrefscale, valuerefscale) { .Deprecated("as.SHE") # You should check that argpotential is valid numeric # IDEA: make a matrix out of these (scale names and flags) # Valid scales scale.names <- list() scale.names[["SHE"]] <- c("SHE", "NHE", "she", "nhe") scale.names[["AgCl"]] <- c("Ag/AgCl", "AgCl", "ag/agcl", "agcl") scale.names[["SCE"]] <- c("SCE", "sce") scale.names[["Li"]] <- c("Li/Li+", "Li", "Li+", "li", "li+", "li/li+") scale.names[["AVS"]] <- c("AVS", "avs") # Set flags bool.flags <- as.data.frame(matrix(0, nrow = length(scale.names), ncol = 2)) names(bool.flags) <- c("argref", "valueref") row.names(bool.flags) <- names(scale.names) # argrefscale # Check that argrefscale is valid character mode # ... # steps through all scale names, "row-by-row", # looking for any cell matching "argrefscale" string # if found, save the position of that refelectrode (in scale.names) to # that row and "argref" column of bool.flags for (j in 1:length(row.names(bool.flags))) { if (any(scale.names[[row.names(bool.flags)[j]]] == argrefscale)) { bool.flags[row.names(bool.flags)[j], "argref"] <- j } } # valuerefscale # Check that valuerefscale is valid character mode # ... for (k in 1:length(row.names(bool.flags))) { if (any(scale.names[[row.names(bool.flags)[k]]] == valuerefscale)) { bool.flags[row.names(bool.flags)[k], "valueref"] <- k } } # Depending on which flags are set, call the corresponding function decision.vector <- colSums(bool.flags) # Check if both scales are the same (no conversion needed). If so, abort gracefully. # ... if (decision.vector["argref"] == 5 || decision.vector["valueref"] == 5) { # AVS is requested, deal with it it if (decision.vector["argref"] == 5) { # Conversion _from_ AVS rnpotential <- ConvertRefPotEC(AVS2SHE(argpotential), "SHE", scale.names[[decision.vector["valueref"]]][1]) } if (decision.vector["valueref"] == 5) { # Conversion _to_ AVS rnpotential <- SHE2AVS(ConvertRefPotEC(argpotential, scale.names[[decision.vector["argref"]]][1], "SHE")) } } else { rnpotential <- ConvertRefPotEC(argpotential, scale.names[[decision.vector["argref"]]][1], scale.names[[decision.vector["valueref"]]][1]) } return(rnpotential) }