How to get the last three months data using dplyr in R-CodePudding

I have data like this:

library(lubridate)
library(dplyr)

set.seed(2021)
gen_date <- seq(ymd_h("2021-01-01-00"), ymd_h("2021-09-30-23"), by = "hours")
hourx <- hour(gen_date)
datex <- date(gen_date)
sales <- round(runif(length(datex), 10, 50), 0)*100
mydata <- data.frame(datex, hourx, sales)

How do i get the last three months data using dplyr? or How do i get the last six months data using dplyr?. What i want is full data from "2021-06-01" to "2021-09-30". Thank You.

CodePudding user response：

We may get the max value of 'datex', create a sequnece of 6 or 3 months with seq backwards, and create a logical vector with 'datex' to filter

library(dplyr)
n <- 6
out <- mydata %>% 
    filter(datex >= seq(floor_date(max(datex), 'month'),
 length.out = n   1, by = '-1 month'))

-checking

> head(out)
       datex hourx sales
1 2021-03-01     4  5000
2 2021-03-01    11  3200
3 2021-03-01    18  1500
4 2021-03-02     1  4400
5 2021-03-02     8  4400
6 2021-03-02    15  4400


> max(mydata$datex)
[1] "2021-09-30"

For 3 months

n <- 3
out2 <- mydata %>% 
    filter(datex >= seq(floor_date(max(datex), 'month'),
 length.out = n   1, by = '-1 month'))
> head(out2)
       datex hourx sales
1 2021-06-01     3  2100
2 2021-06-01     7  1300
3 2021-06-01    11  4800
4 2021-06-01    15  1500
5 2021-06-01    19  3200
6 2021-06-01    23  3400

CodePudding user response：

You may try

library(xts)

x <- mydata %>%
  mutate(month = month(datex)) %>%
  filter(month %in% last(unique(month), 3))
unique(x$month)
[1] 7 8 9