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@Ringa_hyj

# Rの時刻変換と日の差分【lubridate, Time Intervals, Differences day】

More than 1 year has passed since last update.

Rの中で時刻データとして変換してやると、

```https://stat.ethz.ch/R-manual/R-devel/library/base/html/difftime.html
```

ここに乗っているようなことができる。

# 日の差分を求めることが今回の目的

## as.Dateで

```start <- as.Date("20200101", format="%Y%m%d")
end <- as.Date("20200201", format="%Y%m%d")

end - start
```
```Time difference of 31 days
```

difftime関数も同じことやっている

```difftime(end, start)
```

# as.POSIXでも

```start <- as.POSIXct("20200101", format="%Y%m%d")
end <- as.POSIXct("20200201", format="%Y%m%d")
difftime(end, start)
```
```Time difference of 31 days
```

# lubridateほんと最高

```library(lubridate)

start <- ymd("20200101")
end <- ymd("20200201")

difftime(end, start)
```
```Time difference of 31 days
```

# as.numericで数字に直す

```as.numeric(difftime(end, start))
```
```[1] 31
```

# おまけ

```ymd("20200501")
[1] "2020-05-01"
ydm("20200501")
[1] "2020-01-05"
mdy("08202000")
[1] "2000-08-20"
ymd_hms("20200201003059", tz="Japan")
[1] "2020-02-01 00:30:59 JST"
ymd_h("2020020120", tz="Japan")
[1] "2020-02-01 20:00:00 JST"
```

```wday(ymd("20200501"))
[1] 6
wday(ymd("20200502"))
[1] 7
wday(ymd("20200503"))
[1] 1
```

ちなみに
1が月曜日
7が日曜日

lubridateさんホント最高

```https://lubridate.tidyverse.org/
```
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