Extract Only Quarter from a Date in R

Extract only quarter from a date in r

I would do:

# example data
DT = data.table(id = 1:10, d = as.IDate("2003-02-08") + seq(100, by=50, length.out=10))

DT[, qtr := quarter(d)]

    id          d qtr
 1:  1 2003-05-19   2
 2:  2 2003-07-08   3
 3:  3 2003-08-27   3
 4:  4 2003-10-16   4
 5:  5 2003-12-05   4
 6:  6 2004-01-24   1
 7:  7 2004-03-14   1
 8:  8 2004-05-03   2
 9:  9 2004-06-22   2
10: 10 2004-08-11   3

The quarter function is provided by data.table and works on both Date and IDate vectors. (IDate uses integer storage.)

Format date as Year/Quarter

You need to explicilty Vectorize your function:

fun_v <- Vectorize(fun, "x")
fun_v(Data$date)
#[1] "01/01" "01/01" "01/01" "01/02" "01/02" "01/02"

However, when it comes to more or less standard tasks (such as datetime manipulations), there's always a solution already available:

library(zoo)
yq <- as.yearqtr(Data$date, format = "%Y-%m-%d")
yq
#[1] "2001 Q1" "2001 Q1" "2001 Q1" "2001 Q2" "2001 Q2" "2001 Q2"

To convert to your specific format, use

format(yq, format = "%y/0%q")
#[1] "01/01" "01/01" "01/01" "01/02" "01/02" "01/02"

How to get every quarter of a date interval in R?

If df is your data frame, what the following does is generate the sequence of all months from startdate to enddate, retain unique combinations of product and quarters and calculate the average.

library(lubridate)
library(dplyr)

df <- df %>%
  mutate(startdate = ymd(startdate),
         enddate = ymd(enddate)) 

df$output <- mapply(function(x,y) seq(x, y, by =  "month"),
                    df$startdate,
                    df$enddate)

df %>% 
  tidyr::unnest(output) %>%
  mutate(quarter = paste0("Q",quarter(output), " ", year(output))) %>%
  select(-output) %>%
  group_by(product, startdate, enddate, quarter) %>%
  filter(row_number(quarter) == 1) %>%
  summarise(mean(price))

Result for the first row of your data frame would be:

   product  startdate    enddate quarter `mean(price)`
     <int>     <date>     <date>   <chr>         <dbl>
1        1 2012-03-17 2016-09-08 Q1 2012            10
2        1 2012-03-17 2016-09-08 Q1 2013            10
3        1 2012-03-17 2016-09-08 Q1 2014            10
4        1 2012-03-17 2016-09-08 Q1 2015            10
5        1 2012-03-17 2016-09-08 Q1 2016            10
6        1 2012-03-17 2016-09-08 Q2 2012            10
7        1 2012-03-17 2016-09-08 Q2 2013            10
8        1 2012-03-17 2016-09-08 Q2 2014            10
9        1 2012-03-17 2016-09-08 Q2 2015            10
10       1 2012-03-17 2016-09-08 Q2 2016            10
11       1 2012-03-17 2016-09-08 Q3 2012            10
12       1 2012-03-17 2016-09-08 Q3 2013            10
13       1 2012-03-17 2016-09-08 Q3 2014            10
14       1 2012-03-17 2016-09-08 Q3 2015            10
15       1 2012-03-17 2016-09-08 Q3 2016            10
16       1 2012-03-17 2016-09-08 Q4 2012            10
17       1 2012-03-17 2016-09-08 Q4 2013            10
18       1 2012-03-17 2016-09-08 Q4 2014            10
19       1 2012-03-17 2016-09-08 Q4 2015            10

Create a vector of year/quarters from a starting date

Convert the input x to yearqtr class. It represents year and quarter internally as year + 0, 1/4, 1/2 and 3/4 so just add whatever number of quarters needed. It renders them as shown. See ?yearqtr for more info.

library(zoo)

x <- "2021 Q3"
as.yearqtr(x) + seq(0, length = 5) / 4
## [1] "2021 Q3" "2021 Q4" "2022 Q1" "2022 Q2" "2022 Q3"

Convert date field to Quarter in R

The zoo library has created a set of functions to handle year-quarter vectors:

library(zoo)
mydf$var9=as.yearqtr(as.Date( mydf$Order.Date, "%m/%d/%Y" ).

Get beginning of next quarter from current Date in R

1) zoo Convert to "yearqtr" class, add 1/4 and if you want the date at the end of the quarter apply as.Date using frac = 1

library(zoo)

today <- Sys.Date()  # 2016-01-27
as.Date(as.yearqtr(today) + 1/4, frac = 1)
## [1] "2016-06-30"

Omit frac=1 if you want the start of the quarter. Omit as.Date if you want the "yearqtr" object:

as.yearqtr(today) + 1/4
[1] "2016 Q2"

2) base of R. This will give the beginning date of the next quarter with no packages. We use cut to get the beginning of the current quarter, convert to "Date" class and add enough days to get to the next quarter and apply cut and as.Date again:

as.Date(cut(as.Date(cut(today, "quarter")) + 100, "quarter"))
## [1] "2016-04-01"

If you want the end of the quarter add enough days to get to the second next quarter and subtact 1 day to get to the end of the prior quarter:

as.Date(cut(as.Date(cut(today, "quarter")) + 200, "quarter")) - 1
## [1] "2016-06-30"

Convert character field to quarter date in R

If you insist on using the base R as.Date() function, then one option for you to consider is mapping the quarters to months. In the below code, I map the quarter to the first month occurring in that quarter. Then I tag on "01" for the first day in that month, and afterward convert to a date.

trim <- c("1992-4", "1993-1")

trim <- gsub("-1", "-01", trim)       # map first quarter to January
trim <- gsub("-2", "-04", trim)       # map second quarter to April
trim <- gsub("-3", "-07", trim)       # map third quarter to July
trim <- gsub("-4", "-10", trim)       # map fourth quarter October

trim <- paste(trim, "-01", sep="")    # add first day of the month

trim <- as.Date(trim, "%Y-%m-%d")     # convert to date

> trim
[1] "1992-10-01" "1993-01-01"

P.S. This question is sort of a duplicate of this SO post. But it's different enough to merit a new answer IMO.

Get last day in quarter

Here's just one way

library(dplyr)
library(lubridate)
dat %>% 
  group_by(quarter=quarter(date, T)) %>% 
  filter(date==max(date)) %>% 
  ungroup %>% 
  select(-quarter)
# # A tibble: 7 x 2
#         date value
#       <date> <dbl>
# 1 2015-03-31    90
# 2 2015-06-30   181
# 3 2015-09-30   273
# 4 2015-12-31   365
# 5 2016-03-31   456
# 6 2016-06-30   547
# 7 2016-08-01   579

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