Hi,
I'm Aisyah..I have a problem to run my R coding. I want to select maximum value
according to week.
here is my data
Date O3_Conc
20000101 0.033
20000102 0.023
20000103 0.025
20000104 0.041
20000105 0.063
20000106 0.028
20000107 0.068
20000108 0.048
20000109 0.037
20000110 0.042
20000111 0.027
20000112 0.035
20000113 0.063
20000114 0.035
20000115 0.042
20000116 0.028
I want to find the max value from column O3_Conc for only 14 days that refer to
biweekly in month. And the next 14 days for the max value.
I hope that I can get the result like this:
Date Max O3_Conc
20000101 - 20000114 0.068
20000115 - 20000129 0.061
I try many coding but still unavailable.
this example my coding
library(plyr)
data.frame(CA0003)
# format weeks as per requirement (replace "00" with "52" and adjust
corresponding year)
tmp <- list()
tmp$y <- format(df$Date, format="%Y")
tmp$w <- format(df$Date, format="%U")
tmp$y[tmp$w=="00"] <- as.character(as.numeric(tmp$y[tmp$w=="00"]) - 14)
tmp$w[tmp$w=="00"] <- "884"
df$week <- paste(tmp$y, tmp$w, sep = "-")
# get summary
df2 <- ddply(df, .(week),transform, O3_Conc=max(O3_Conc))
# include week ending date
tmp$week.ending <- lapply(df2$week, function(x) rev(df[df$week ==x,
"O3_Conc"])[[1]])
df2$week.ending <- sapply(tmp$week.ending, max(O3_Conc, TRUE)
output
Site_Id Site_Location Date
Year O3_Conc Month Day week
1 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000101
2000 0.033 1 1 NULL-NULL
2 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000102
2000 0.023 1 2 NULL-NULL
3 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000103
2000 0.025 1 3 NULL-NULL
4 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000104
2000 0.041 1 4 NULL-NULL
5 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000105
2000 0.063 1 5 NULL-NULL
6 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000106
2000 0.028 1 6 NULL-NULL
7 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000107
2000 0.068 1 7 NULL-NULL
8 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000108
2000 0.048 1 8 NULL-NULL
9 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000109
2000 0.037 1 9 NULL-NULL
10 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000110
2000 0.042 1 10 NULL-NULL
11 CA0003 Sek. Keb. Cederawasih, Taman Inderawasih, Perai 20000111
2000 0.027 1 11 NULL-NULL
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