'How can I subset my list to have only the last day of the month?
DGS1MO DGS3MO DGS1 DGS2 DGS3 DGS5 DGS7 DGS10 DGS20 DGS30
2001-07-31 3.67 3.54 3.53 3.79 4.06 4.57 4.86 5.07 5.61 5.51
2001-08-01 3.65 3.53 3.56 3.83 4.09 4.62 4.90 5.11 5.63 5.53
2001-08-02 3.65 3.53 3.57 3.89 4.17 4.69 4.97 5.17 5.68 5.57
2001-08-03 3.63 3.52 3.57 3.91 4.22 4.72 4.99 5.20 5.70 5.59
2001-08-06 3.62 3.52 3.56 3.88 4.17 4.71 4.99 5.19 5.70 5.59
2001-08-07 3.63 3.52 3.56 3.90 4.19 4.72 5.00 5.20 5.71 5.60
2001-08-08 3.61 3.49 3.46 3.77 4.05 4.61 4.87 4.99 5.61 5.52
2001-08-09 3.61 3.45 3.48 3.77 4.07 4.66 4.93 5.04 5.64 5.54
2001-08-10 3.58 3.43 3.45 3.73 4.03 4.61 4.88 4.99 5.61 5.52
2001-08-13 3.57 3.45 3.43 3.70 4.00 4.57 4.86 4.97 5.60 5.52
2001-08-14 3.54 3.43 3.46 3.74 4.03 4.59 4.87 4.97 5.61 5.51
2001-08-15 3.52 3.43 3.47 3.80 4.11 4.62 4.90 5.00 5.62 5.52
2001-08-16 3.48 3.39 3.43 3.75 4.04 4.58 4.84 4.95 5.58 5.48
2001-08-17 3.46 3.36 3.39 3.67 3.95 4.49 4.75 4.84 5.51 5.43
2001-08-20 3.48 3.42 3.44 3.74 4.02 4.55 4.81 4.91 5.55 5.46
2001-08-21 3.46 3.39 3.41 3.69 3.96 4.50 4.79 4.87 5.54 5.44
2001-08-22 3.46 3.38 3.44 3.76 4.03 4.53 4.81 4.91 5.53 5.44
2001-08-23 3.49 3.40 3.46 3.72 3.99 4.52 4.79 4.89 5.50 5.41
2001-08-24 3.49 3.42 3.48 3.76 4.03 4.55 4.82 4.93 5.54 5.45
2001-08-27 3.52 3.45 3.51 3.78 4.04 4.57 4.83 4.94 5.56 5.47
2001-08-28 3.53 3.41 3.46 3.71 3.97 4.48 4.73 4.85 5.49 5.41
2001-08-29 3.48 3.42 3.44 3.67 3.92 4.43 4.67 4.78 5.44 5.36
2001-08-30 3.41 3.36 3.38 3.61 3.88 4.42 4.68 4.79 5.45 5.37
2001-08-31 3.40 3.37 3.41 3.64 3.91 4.46 4.72 4.85 5.47 5.39
2001-09-04 3.43 3.44 3.55 3.83 4.10 4.63 4.88 4.99 5.59 5.50
2001-09-05 3.49 3.41 3.47 3.79 4.07 4.61 4.86 4.97 5.57 5.48
2001-09-06 3.44 3.34 3.40 3.65 3.93 4.48 4.73 4.86 5.50 5.41
2001-09-07 3.40 3.27 3.29 3.53 3.82 4.39 4.67 4.80 5.45 5.39
2001-09-10 3.40 3.26 3.31 3.53 3.82 4.41 4.69 4.84 5.50 5.43
2001-09-13 2.73 2.74 2.81 2.99 3.32 4.03 4.41 4.64 5.41 5.39
2001-09-14 2.54 2.64 2.73 2.87 3.17 3.92 4.31 4.57 5.38 5.35
2001-09-17 2.47 2.59 2.72 2.96 3.30 3.99 4.38 4.63 5.44 5.41
2001-09-18 2.34 2.48 2.69 2.96 3.31 4.01 4.46 4.72 5.59 5.55
2001-09-19 2.00 2.19 2.49 2.81 3.18 3.90 4.41 4.69 5.59 5.56
2001-09-20 2.04 2.22 2.56 2.91 3.27 3.97 4.47 4.75 5.67 5.62
2001-09-21 2.12 2.25 2.53 2.91 3.27 3.94 4.43 4.70 5.62 5.59
2001-09-24 2.38 2.38 2.56 2.94 3.30 4.00 4.47 4.73 5.61 5.58
2001-09-25 2.58 2.40 2.51 2.88 3.25 3.97 4.45 4.72 5.60 5.58
2001-09-26 2.51 2.38 2.48 2.82 3.18 3.91 4.39 4.65 5.52 5.50
2001-09-27 2.34 2.38 2.43 2.78 3.15 3.87 4.33 4.58 5.46 5.45
2001-09-28 2.28 2.40 2.49 2.86 3.22 3.93 4.37 4.60 5.45 5.42
2001-10-01 2.26 2.37 2.47 2.82 3.18 3.90 4.33 4.55 5.39 5.38
2001-10-02 2.27 2.26 2.43 2.77 3.14 3.87 4.31 4.53 5.36 5.34
2001-10-03 2.21 2.23 2.38 2.77 3.14 3.86 4.29 4.50 5.34 5.32
2001-10-04 2.22 2.21 2.37 2.75 3.14 3.88 4.29 4.53 5.33 5.31
2001-10-05 2.21 2.19 2.33 2.71 3.10 3.87 4.26 4.52 5.34 5.31
2001-10-09 2.24 2.22 2.35 2.74 3.16 3.96 4.35 4.62 5.42 5.39
Above I have my dataset that I am trying to subset. My goals is to subset the df to only include the last day of each month listed. For example 8/31/2021,9/27/2021...etc onward through the data. I have been able to do specific dates but I need something that is dynamic. Thanks in advance
Solution 1:[1]
With lubridate:
library(lubridate)
df$DAY <- as.Date(df$DAY)
df[df$DAY == ceiling_date(df$DAY,'month') - days(1),]
DAY DGS1MO DGS3MO DGS1 DGS2 DGS3 DGS5 DGS7 DGS10 DGS20 DGS30
1 2001-07-31 3.67 3.54 3.53 3.79 4.06 4.57 4.86 5.07 5.61 5.51
24 2001-08-31 3.40 3.37 3.41 3.64 3.91 4.46 4.72 4.85 5.47 5.39
df:
df <- read.table(text='
DAY DGS1MO DGS3MO DGS1 DGS2 DGS3 DGS5 DGS7 DGS10 DGS20 DGS30
2001-07-31 3.67 3.54 3.53 3.79 4.06 4.57 4.86 5.07 5.61 5.51
2001-08-01 3.65 3.53 3.56 3.83 4.09 4.62 4.90 5.11 5.63 5.53
2001-08-02 3.65 3.53 3.57 3.89 4.17 4.69 4.97 5.17 5.68 5.57
2001-08-03 3.63 3.52 3.57 3.91 4.22 4.72 4.99 5.20 5.70 5.59
2001-08-06 3.62 3.52 3.56 3.88 4.17 4.71 4.99 5.19 5.70 5.59
2001-08-07 3.63 3.52 3.56 3.90 4.19 4.72 5.00 5.20 5.71 5.60
2001-08-08 3.61 3.49 3.46 3.77 4.05 4.61 4.87 4.99 5.61 5.52
2001-08-09 3.61 3.45 3.48 3.77 4.07 4.66 4.93 5.04 5.64 5.54
2001-08-10 3.58 3.43 3.45 3.73 4.03 4.61 4.88 4.99 5.61 5.52
2001-08-13 3.57 3.45 3.43 3.70 4.00 4.57 4.86 4.97 5.60 5.52
2001-08-14 3.54 3.43 3.46 3.74 4.03 4.59 4.87 4.97 5.61 5.51
2001-08-15 3.52 3.43 3.47 3.80 4.11 4.62 4.90 5.00 5.62 5.52
2001-08-16 3.48 3.39 3.43 3.75 4.04 4.58 4.84 4.95 5.58 5.48
2001-08-17 3.46 3.36 3.39 3.67 3.95 4.49 4.75 4.84 5.51 5.43
2001-08-20 3.48 3.42 3.44 3.74 4.02 4.55 4.81 4.91 5.55 5.46
2001-08-21 3.46 3.39 3.41 3.69 3.96 4.50 4.79 4.87 5.54 5.44
2001-08-22 3.46 3.38 3.44 3.76 4.03 4.53 4.81 4.91 5.53 5.44
2001-08-23 3.49 3.40 3.46 3.72 3.99 4.52 4.79 4.89 5.50 5.41
2001-08-24 3.49 3.42 3.48 3.76 4.03 4.55 4.82 4.93 5.54 5.45
2001-08-27 3.52 3.45 3.51 3.78 4.04 4.57 4.83 4.94 5.56 5.47
2001-08-28 3.53 3.41 3.46 3.71 3.97 4.48 4.73 4.85 5.49 5.41
2001-08-29 3.48 3.42 3.44 3.67 3.92 4.43 4.67 4.78 5.44 5.36
2001-08-30 3.41 3.36 3.38 3.61 3.88 4.42 4.68 4.79 5.45 5.37
2001-08-31 3.40 3.37 3.41 3.64 3.91 4.46 4.72 4.85 5.47 5.39
2001-09-04 3.43 3.44 3.55 3.83 4.10 4.63 4.88 4.99 5.59 5.50
2001-09-05 3.49 3.41 3.47 3.79 4.07 4.61 4.86 4.97 5.57 5.48
2001-09-06 3.44 3.34 3.40 3.65 3.93 4.48 4.73 4.86 5.50 5.41
2001-09-07 3.40 3.27 3.29 3.53 3.82 4.39 4.67 4.80 5.45 5.39
2001-09-10 3.40 3.26 3.31 3.53 3.82 4.41 4.69 4.84 5.50 5.43
2001-09-13 2.73 2.74 2.81 2.99 3.32 4.03 4.41 4.64 5.41 5.39
2001-09-14 2.54 2.64 2.73 2.87 3.17 3.92 4.31 4.57 5.38 5.35
2001-09-17 2.47 2.59 2.72 2.96 3.30 3.99 4.38 4.63 5.44 5.41
2001-09-18 2.34 2.48 2.69 2.96 3.31 4.01 4.46 4.72 5.59 5.55
2001-09-19 2.00 2.19 2.49 2.81 3.18 3.90 4.41 4.69 5.59 5.56
2001-09-20 2.04 2.22 2.56 2.91 3.27 3.97 4.47 4.75 5.67 5.62
2001-09-21 2.12 2.25 2.53 2.91 3.27 3.94 4.43 4.70 5.62 5.59
2001-09-24 2.38 2.38 2.56 2.94 3.30 4.00 4.47 4.73 5.61 5.58
2001-09-25 2.58 2.40 2.51 2.88 3.25 3.97 4.45 4.72 5.60 5.58
2001-09-26 2.51 2.38 2.48 2.82 3.18 3.91 4.39 4.65 5.52 5.50
2001-09-27 2.34 2.38 2.43 2.78 3.15 3.87 4.33 4.58 5.46 5.45
2001-09-28 2.28 2.40 2.49 2.86 3.22 3.93 4.37 4.60 5.45 5.42
2001-10-01 2.26 2.37 2.47 2.82 3.18 3.90 4.33 4.55 5.39 5.38
2001-10-02 2.27 2.26 2.43 2.77 3.14 3.87 4.31 4.53 5.36 5.34
2001-10-03 2.21 2.23 2.38 2.77 3.14 3.86 4.29 4.50 5.34 5.32
2001-10-04 2.22 2.21 2.37 2.75 3.14 3.88 4.29 4.53 5.33 5.31
2001-10-05 2.21 2.19 2.33 2.71 3.10 3.87 4.26 4.52 5.34 5.31
2001-10-09 2.24 2.22 2.35 2.74 3.16 3.96 4.35 4.62 5.42 5.39',header=T)
Solution 2:[2]
A date is the last of a month if and only if it is one day prior to the first of the following month. You can index the elements of a Date vector x satisfying this condition like so:
is_last_of_month <- function(x) {
x <- trunc(x)
x == as.Date(round(as.POSIXlt(x), units = "months")) - 1
}
x <- seq(as.Date("2022-02-24"), as.Date("2022-03-05"), by = 1)
x
## [1] "2022-02-24" "2022-02-25" "2022-02-26" "2022-02-27" "2022-02-28"
## [6] "2022-03-01" "2022-03-02" "2022-03-03" "2022-03-04" "2022-03-05"
is_last_of_month(x)
## [1] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE
is_last_of_month operates on trunc(x) instead of x to defend against the possibility of fractional days, so that—for example—is_last_of_month(as.Date("2022-02-28") + u) is TRUE for all u greater than 0 but less than 1:
y <- as.Date("2022-02-28") + 0.5
y
## [1] "2022-02-28"
y == as.Date(round(as.POSIXlt(y), units = "months")) - 1
## [1] FALSE
is_last_of_month(y)
## [1] TRUE
(Well, "... for all u greater than 0 but less than 1" is not quite true in floating point arithmetic, but hopefully my meaning is clear.)
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | Waldi |
| Solution 2 |