Some slight speedups of convert units

R/general.R

@@ -247,109 +247,124 @@ plot_ions <- function(water) {
 }
 
 
-#' @title Calculate unit conversions for common compounds
-#'
-#' @description This function takes a value and converts units based on compound name.
-#'
-#' @param value Value to be converted
-#' @param formula Chemical formula of compound. Accepts compounds in mweights for conversions between g and mol or eq
-#' @param startunit Units of current value, currently accepts g/L; g/L CaCO3; g/L N; M; eq/L;
-#' and the same units with "m", "u", "n" prefixes
-#' @param endunit Desired units, currently accepts same as start units
-#'
-#' @examples
-#' convert_units(50, "ca") # converts from mg/L to M by default
-#' convert_units(50, "ca", "mg/L", "mg/L CaCO3")
-#' convert_units(50, "ca", startunit = "mg/L", endunit = "eq/L")
-#'
-#' @export
-#'
-#' @returns A numeric value for the converted parameter.
-#'
-convert_units <- function(value, formula, startunit = "mg/L", endunit = "M") {
-  milli_list <- c("mg/L", "mg/L CaCO3", "mg/L N", "mM", "meq/L")
-  mcro_list <- c("ug/L", "ug/L CaCO3", "ug/L N", "uM", "ueq/L")
-  nano_list <- c("ng/L", "ng/L CaCO3", "ng/L N", "nM", "neq/L")
-  stand_list <- c("g/L", "g/L CaCO3", "g/L N", "M", "eq/L")
-
+# Using a some package local environments to cache some hashmaps for fast lookups
+# Create an environment to act as a hashmap:
+# See: https://riptutorial.com/r/example/18339/environments-as-hash-maps
+convert_units.unit_to_mult <- new.env(parent = emptyenv())
+# All the standard units
+convert_units.unit_to_mult[["g/L"]] <- 1
+convert_units.unit_to_mult[["g/L CaCO3"]] <- 1
+convert_units.unit_to_mult[["g/L N"]] <- 1
+convert_units.unit_to_mult[["M"]] <- 1
+convert_units.unit_to_mult[["eq/L"]] <- 1
+# All the milli units
+convert_units.unit_to_mult[["mg/L"]] <- 1e-3
+convert_units.unit_to_mult[["mg/L CaCO3"]] <- 1e-3
+convert_units.unit_to_mult[["mg/L N"]] <- 1e-3
+convert_units.unit_to_mult[["mM"]] <- 1e-3
+convert_units.unit_to_mult[["meq/L"]] <- 1e-3
+# All the mirco units
+convert_units.unit_to_mult[["ug/L"]] <- 1e-6
+convert_units.unit_to_mult[["ug/L CaCO3"]] <- 1e-6
+convert_units.unit_to_mult[["ug/L N"]] <- 1e-6
+convert_units.unit_to_mult[["uM"]] <- 1e-6
+convert_units.unit_to_mult[["ueq/L"]] <- 1e-6
+# All the nano units
+convert_units.unit_to_mult[["ng/L"]] <- 1e-9
+convert_units.unit_to_mult[["ng/L CaCO3"]] <- 1e-9
+convert_units.unit_to_mult[["ng/L N"]] <- 1e-9
+convert_units.unit_to_mult[["nM"]] <- 1e-9
+convert_units.unit_to_mult[["neq/L"]] <- 1e-9
+
+convert_units.formula_to_charge <- new.env(parent = emptyenv())
+convert_units.formula_to_charge[["na"]] <- 1
+convert_units.formula_to_charge[["k"]] <- 1
+convert_units.formula_to_charge[["cl"]] <- 1
+convert_units.formula_to_charge[["hcl"]] <- 1
+convert_units.formula_to_charge[["naoh"]] <- 1
+convert_units.formula_to_charge[["nahco3"]] <- 1
+convert_units.formula_to_charge[["nh4"]] <- 1
+convert_units.formula_to_charge[["na"]] <- 1
+convert_units.formula_to_charge[["f"]] <- 1
+convert_units.formula_to_charge[["br"]] <- 1
+convert_units.formula_to_charge[["bro3"]] <- 1
+convert_units.formula_to_charge[["so4"]] <- 2
+convert_units.formula_to_charge[["caco3"]] <- 2
+convert_units.formula_to_charge[["h2so4"]] <- 2
+convert_units.formula_to_charge[["na2co3"]] <- 2
+convert_units.formula_to_charge[["caoh2"]] <- 2
+convert_units.formula_to_charge[["mgoh2"]] <- 2
+convert_units.formula_to_charge[["mg"]] <- 2
+convert_units.formula_to_charge[["ca"]] <- 2
+convert_units.formula_to_charge[["pb"]] <- 2
+convert_units.formula_to_charge[["cacl2"]] <- 2
+convert_units.formula_to_charge[["mn"]] <- 2
+convert_units.formula_to_charge[["h3po4"]] <- 3
+convert_units.formula_to_charge[["al"]] <- 3
+convert_units.formula_to_charge[["fe"]] <- 3
+convert_units.formula_to_charge[["alum"]] <- 3
+convert_units.formula_to_charge[["fecl3"]] <- 3
+# TODO ASK SIERRA (fe2so43 is not in mweights)
+#convert_units.formula_to_charge[["fe2so43"]] <- 3
+convert_units.formula_to_charge[["po4"]] <- 3
+
+# Internal conversion function
+convert_units_private <- function(value, formula, startunit = "mg/L", endunit = "M") {
   gram_list <- c(
     "ng/L", "ug/L", "mg/L", "g/L",
     "ng/L CaCO3", "ug/L CaCO3", "mg/L CaCO3", "g/L CaCO3",
     "ng/L N", "ug/L N", "mg/L N", "g/L N"
   )
   mole_list <- c("M", "mM", "uM", "nM")
   eqvl_list <- c("neq/L", "ueq/L", "meq/L", "eq/L")
-
+  
   caco_list <- c("mg/L CaCO3", "g/L CaCO3", "ug/L CaCO3", "ng/L CaCO3")
   n_list <- c("mg/L N", "g/L N", "ug/L N", "ng/L N")
-
-  # Determine multiplier for order of magnitude conversion
-  # In the same list, no multiplier needed
-  if ((startunit %in% milli_list & endunit %in% milli_list) |
-    (startunit %in% stand_list & endunit %in% stand_list) |
-    (startunit %in% nano_list & endunit %in% nano_list) |
-    (startunit %in% mcro_list & endunit %in% mcro_list)) {
-    multiplier <- 1
-    # m - standard, n-u, u-n
-  } else if ((startunit %in% milli_list & endunit %in% stand_list) |
-    (startunit %in% mcro_list & endunit %in% milli_list) |
-    (startunit %in% nano_list & endunit %in% mcro_list)) {
-    multiplier <- 1e-3
-  } else if ((startunit %in% stand_list & endunit %in% milli_list) |
-    (startunit %in% milli_list & endunit %in% mcro_list) |
-    (startunit %in% mcro_list & endunit %in% nano_list)) {
-    multiplier <- 1e3
-    # u - standard
-  } else if ((startunit %in% mcro_list & endunit %in% stand_list) |
-    (startunit %in% nano_list & endunit %in% milli_list)) {
-    multiplier <- 1e-6
-  } else if ((startunit %in% stand_list & endunit %in% mcro_list) |
-    (startunit %in% milli_list & endunit %in% nano_list)) {
-    multiplier <- 1e6
-    # n - standard
-  } else if (startunit %in% nano_list & endunit %in% stand_list) {
-    multiplier <- 1e-9
-  } else if (startunit %in% stand_list & endunit %in% nano_list) {
-    multiplier <- 1e9
-  } else {
+
+  # Look up the unit multipliers for starting and end units
+  start_mult <- convert_units.unit_to_mult[[startunit]]
+  end_mult <- convert_units.unit_to_mult[[endunit]]
+  if (is.null(start_mult) || is.null(end_mult)) {
+    # If we didn't find multipliers these units are not supported
     stop("Units not supported")
   }
-
+  # Calculate the net multiplier
+  multiplier <- start_mult / end_mult
+
   # Need molar mass of CaCO3 and N
   caco3_mw <- as.numeric(tidywater::mweights["caco3"])
   n_mw <- as.numeric(tidywater::mweights["n"])
-
+  
   # Determine relevant molar weight
   if (formula %in% colnames(tidywater::mweights)) {
     if ((startunit %in% caco_list & endunit %in% c(mole_list, eqvl_list)) |
-      (endunit %in% caco_list & startunit %in% c(mole_list, eqvl_list))) {
+        (endunit %in% caco_list & startunit %in% c(mole_list, eqvl_list))) {
       molar_weight <- caco3_mw
     } else if ((startunit %in% n_list & endunit %in% c(mole_list, eqvl_list)) |
-      (endunit %in% n_list & startunit %in% c(mole_list, eqvl_list))) {
+               (endunit %in% n_list & startunit %in% c(mole_list, eqvl_list))) {
       molar_weight <- n_mw
     } else {
       molar_weight <- as.numeric(tidywater::mweights[formula])
     }
   } else if (!(startunit %in% gram_list) & !(endunit %in% gram_list)) {
     molar_weight <- 0
   } else {
-    stop("Chemical formula not supported")
+    stop(paste("Chemical formula not supported: ", formula))
   }
-
+  
   # Determine charge for equivalents
-  if (formula %in% c("na", "k", "cl", "hcl", "naoh", "nahco3", "na", "nh4", "f", "br", "bro3")) {
-    charge <- 1
-  } else if (formula %in% c("so4", "caco3", "h2so4", "na2co3", "caoh2", "mgoh2", "mg", "ca", "pb", "cacl2", "mn")) {
-    charge <- 2
-  } else if (formula %in% c("h3po4", "al", "fe", "alum", "fecl3", "fe2so43", "po4")) {
-    charge <- 3
+  # Look up our known charges in our hashtable
+  table_charge <- convert_units.formula_to_charge[[formula]]
+  if (!is.null(table_charge)) {
+    # If we found a charge in the hash table use that
+    charge <- table_charge
   } else if (!(startunit %in% eqvl_list) & !(endunit %in% eqvl_list)) {
     # This is included so that charge can be in equations later without impacting results
     charge <- 1
   } else {
     stop("Unable to find charge for equivalent conversion")
   }
-
+  
   # Unit conversion
   # g - mol
   if (startunit %in% gram_list & endunit %in% mole_list) {
@@ -378,14 +393,65 @@ convert_units <- function(value, formula, startunit = "mg/L", endunit = "M") {
     value / molar_weight * n_mw
     # same lists
   } else if ((startunit %in% gram_list & endunit %in% gram_list) |
-    (startunit %in% mole_list & endunit %in% mole_list) |
-    (startunit %in% eqvl_list & endunit %in% eqvl_list)) {
+             (startunit %in% mole_list & endunit %in% mole_list) |
+             (startunit %in% eqvl_list & endunit %in% eqvl_list)) {
     value * multiplier
   } else {
     stop("Units not supported")
   }
 }
 
+generate_conversions_table <- function() {
+  # All units we support
+  units <- ls(convert_units.unit_to_mult)
+  # All formulas we support
+  formulas <- ls(convert_units.formula_to_charge)
+  env <- new.env(parent = emptyenv())
+  for (startunit in units) {
+    for (endunit in units) {
+      for (formula in formulas) {
+        name <- paste(formula,startunit,endunit)
+        env[[name]] <- convert_units_private(1.0, formula, startunit, endunit)
+      }
+    }
+  }
+  env
+}
+
+# Pre-compute all unit conversions and store in env on package load
+# Could probably put this in a .rdata file instead?
+convert_units.super_table <- generate_conversions_table()
+
+
+#' @title Calculate unit conversions for common compounds
+#'
+#' @description This function takes a value and converts units based on compound name.
+#'
+#' @param value Value to be converted
+#' @param formula Chemical formula of compound. Accepts compounds in mweights for conversions between g and mol or eq
+#' @param startunit Units of current value, currently accepts g/L; g/L CaCO3; g/L N; M; eq/L;
+#' and the same units with "m", "u", "n" prefixes
+#' @param endunit Desired units, currently accepts same as start units
+#'
+#' @examples
+#' convert_units(50, "ca") # converts from mg/L to M by default
+#' convert_units(50, "ca", "mg/L", "mg/L CaCO3")
+#' convert_units(50, "ca", startunit = "mg/L", endunit = "eq/L")
+#'
+#' @export
+#'
+#' @returns A numeric value for the converted parameter.
+#'
+convert_units <- function(value, formula, startunit = "mg/L", endunit = "M") {
+  lookup <- convert_units.super_table[[paste(formula, startunit, endunit)]]
+  if (is.null(lookup)) {
+    # Fallback to full implementation
+    convert_units_private(value, formula, startunit, endunit)
+  }else {
+    value * lookup
+  }
+}
+
 
 #' @title Calculate hardness from calcium and magnesium
 #'