使用汇总求和的R中的值大于70

Question

I am trying to sum values that are greater than 70 in several different data sets. I believe that aggregate can do this but my research has not pointed to an obvious solution to obtaining the values that exceed seventy in my data sets. I have first used aggregate to get the daily max values and put these values into the data frame called yearmaxs. Here is my code and what I have tried:

number of times O3 >70 in a year per site

Sys.setenv(TZ = "UTC")
library(openair)
library(lubridate)
filedir <- "C:/Users/dfmcg/Documents/Thesisfiles/8hravg"
myfiles <- c(list.files(path = filedir))
paste(filedir, myfiles, sep = '/')
npsfiles <- c(paste(filedir, myfiles,sep = '/'))

for (i in npsfiles[22]) {

  x <- substr(i,45,61)
  y <- paste('C:/Users/dfmcg/Documents/Thesisfiles/exceedenceall', x, sep='/')
  timeozone <- import(i, date="DATES", date.format = "%Y-%m-%d %H", header=TRUE, na.strings="NA")

  overseventy <- c()
  yearmaxs <- aggregate(rolling.O3new ~ format(as.Date(date)), timeozone, max)
  colnames(yearmaxs) <- c("date", "daymax")
  overseventy <- aggregate(daymax ~ format(as.Date(date)), yearmaxs, FUN = length,
        subset = as.numeric(daymax) > 70)
  colnames(overseventy) <- c("date", "daymax")
  aggregate(daymax ~ format(as.Date(date), "%Y"), overseventy, sum)

I have also tried: sum > "70 and sum(daymax > "70).

My other idea at this point is using a for loop to iterate through the values. I was hoping that a could use aggregate again to sum the values of interest. Any help at all would be greatly appreciated!

Answer 1

I think you want:

aggregate(daymax ~ format(as.Date(date)), yearmaxs, FUN = length,
          subset = as.numeric(daymax) > 70)

To things:

1. you need numerical comparison, so use as.numeric(daymax) > 70 not daymax > "70" ;
2. use the subset argument in aggregate.formula .