R/clean_neg.R

In bcgov/rcaaqs: Tools to implement CAAQS analysis for air quality

# Copyright 2015 Province of British Columbia
# 
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
# 
# http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.


#' Replaces negative values in a vector of air quality readings with 
#' CAAQS-compliant values
#'
#' @param x vector of air quality readings
#' @param  type type of air quality readings; one of: "pm25", "ozone", "so2", 
#'   "no2"
#'  
#' @details For gases (type = "ozone", "so2", or "no2"), replaces values 
#'   \eqn{\le} -5 with `NA` and values between -5 and 0 with 0. For type = 
#'   "pm25", replaces values \eqn{\le} -3.5 with `NA` and values between 
#'   -3.5 and 0 with 0.
#'  
#' @return a vector of the same length as x with negative values replaced with 
#'   CAAQS compliant values
#'
#'@export

clean_neg <- function(x, type = c("pm25", "ozone", "so2", "no2")) {
  type <- tolower(type)
  type <- match.arg(type)
  cutoff <- switch(type, 
                 nox = -5, so2 = -5, ozone = -5, pm25 = -3.5)
  x[x <= cutoff] <- NA
  x[x < 0] <- 0
  x
}