define quarter columns with conditions - r

Question

I have a dataframe as follow:
ID Mois Year
A 12 2010
B 01 2011
C 04 2010
D 05 2011
E 07 2011
F 11 2010
G 12 2011
H 03 2010
I 01 2012
J 02 2012
I wouls like to add quarter columns as:
quarter1: ( 12(of n-1), 01 of n, 02 of n): means (12 of 2010, 01 of
2011, 02 of 2011)
quarter2:(03 of n , 04 of n, 05 of n)
quarter3: (06 of n, O7 of n, O8of n)
quarter4:( 09of n, 10 of n, 11
of n)
I have tried this code `
data=cbind(data, quarter=ifelse(data$mois==c(12,1,2), "1",
ifelse(data$mois==c(3,4,5),"2",
ifelse(data$mois==c(6,7,8),"3", "4"))))
but it does not work and i dont know how to add the condition of the quarter1 as( 12(of n-1), 01 of n, 02 of n): means (12 of 2010, 01 of 2011, 02 of 2011)
or can we replace data$year where data$month == 12 to year + 1, before doing the quarter?
Any help would be much appreciated.

Answer 1

1) formula We can use this formula to calculate quarters:
transform(data, YearQ = Year + (Mois == 12), Quarter = Mois %% 12 %/% 3 + 1)
giving:
ID Mois Year YearQ Quarter
1 A 12 2010 2011 1
2 B 1 2011 2011 1
3 C 4 2010 2010 2
4 D 5 2011 2011 2
5 E 7 2011 2011 3
6 F 11 2010 2010 4
7 G 12 2011 2012 1
8 H 3 2010 2010 2
9 I 1 2012 2012 1
10 J 2 2012 2012 1
2) yearqtr Another possibility is to use "yearqtr" class giving the same result:
library(zoo)
transform(data, YearQ = Year + (Mois == 12), Quarter = cycle(as.yearqtr(Year + Mois/12)))
giving same as (1).
2a) Alternately we may just wish to create yearmon and yearqtr columns:
transform(data, ym = as.yearmon(Year + (Mois -1)/12), yq = as.yearqtr(Year + Mois/12))
giving:
ID Mois Year ym yq
1 A 12 2010 Dec 2010 2011 Q1
2 B 1 2011 Jan 2011 2011 Q1
3 C 4 2010 Apr 2010 2010 Q2
4 D 5 2011 May 2011 2011 Q2
5 E 7 2011 Jul 2011 2011 Q3
6 F 11 2010 Nov 2010 2010 Q4
7 G 12 2011 Dec 2011 2012 Q1
8 H 3 2010 Mar 2010 2010 Q2
9 I 1 2012 Jan 2012 2012 Q1
10 J 2 2012 Feb 2012 2012 Q1
3) switch We can use switch like this:
transform(data, YearQ = Year + (Mois == 12),
Quarter = sapply(Mois, switch, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 1)))
giving same as (1).
Note
The input data in reproducible form is:
Lines <- "
ID Mois Year
A 12 2010
B 01 2011
C 04 2010
D 05 2011
E 07 2011
F 11 2010
G 12 2011
H 03 2010
I 01 2012
J 02 2012"
data <- read.table(text = Lines, header = TRUE)

Answer 2

If you can do with the new column quarter of class factor, then cut will do it.
m <- data$Mois
m[m == 12] <- 0
data$quarter <- cut(m, breaks = c(-1, 2, 5, 8, 11), labels = as.character(1:4))
rm(m) # tidy up
If you really need or want class character, just coerce it.
data$quarter <- as.character(data$quarter)
DATA.
dput(data)
structure(list(ID = structure(1:10, .Label = c("A", "B", "C",
"D", "E", "F", "G", "H", "I", "J"), class = "factor"), Mois = c(12L,
1L, 4L, 5L, 7L, 11L, 12L, 3L, 1L, 2L), Year = c(2010L, 2011L,
2010L, 2011L, 2011L, 2010L, 2011L, 2010L, 2012L, 2012L)), .Names = c("ID",
"Mois", "Year"), class = "data.frame", row.names = c(NA, -10L
))

Answer 3

Another option could be using the same line of solution as that of OP. Add quarter column using ifelse and then modify year using ifelse too.
data$quarter <- ifelse(data$Mois %in% c(12,1,2), "1",
ifelse(data$Mois %in% c(3,4,5),"2",
ifelse(data$Mois %in% c(6,7,8),"3", "4")))
data$Year <- ifelse(data$Mois == 12, data$Year + 1, data$Year)
data
ID Mois Year quarter
1 A 12 2011 1
2 B 1 2011 1
3 C 4 2010 2
4 D 5 2011 2
5 E 7 2011 3
6 F 11 2010 4
7 G 12 2012 1
8 H 3 2010 2
9 I 1 2012 1
10 J 2 2012 1
Data:
data <- read.table(text = "ID Mois Year
A 12 2010
B 01 2011
C 04 2010
D 05 2011
E 07 2011
F 11 2010
G 12 2011
H 03 2010
I 01 2012
J 02 2012", header = TRUE, stringsAsFactor = FALSE)