我有一个位置很多的数据框（大约30.000），我需要将每个位置的时间转换为本地时间。我尝试了一些想法，例如this one和this one。但是他们没有为我工作。
我有这样的数据：
dt = data.table(date = c("2018-01-16 22:02:37",
"2018-01-16 22:54:00",
"2018-01-16 23:08:38"),
lat = c(-54.5010,
-54.5246,
-54.5285),
long = c(-25.0433,
-25.0929,
-25.0832))
而且我期望此输出：
date lat long
2018-01-16 20:02:37 -54.5010 -25.0433
2018-01-16 20:54:00 -54.5246 -25.0929
2018-01-16 21:08:38 -54.5285 -25.0832
一次尝试：
library(sf)
dt = data.table(date = c("2018-01-16 22:02:37",
"2018-01-16 22:54:00",
"2018-01-16 23:08:38"),
lat = c(-54.5010,
-54.5246,
-54.5285),
long = c(-25.0433,
-25.0929,
-25.0832))
sdf = st_as_sf(dt, coords = c("long", "lat"), crs = 4326)
## import timezones (after extraction) and intersect with spatial points
tzs = st_read("timezones.geojson/combined.json", quiet = TRUE) #HERE DONT WORK
sdf = st_join(sdf, tzs)
## convert timestamps to local time
sdf$timeL = as.POSIXlt(sdf$time1, tz = as.character(sdf$tzid))
sdf$timeL
Cannot open data source timezones.geojson/combined.json
Error in CPL_read_ogr(dsn, layer, query, as.character(options), quiet, :
Open failed.
然后我尝试：
library(lutz)
library(sf)
library(purrr)
library(dplyr)
download.file("https://github.com/evansiroky/timezone-boundary-builder/releases/download/2019a/timezones-with-oceans.geojson.zip",
destfile = "tz.zip")
unzip("tz.zip", exdir = "data-raw/dist/")
tz_full <- read_sf("data-raw/dist/combined-with-oceans.json")
但是这也不起作用。
Cannot open data source ~/Dropbox/Érika Project/mestrado_R/bhv_loc_R/tables/data-raw/dist/combined-with-oceans.json
Error in CPL_read_ogr(dsn, layer, query, as.character(options), quiet, :
Open failed.
我就这样得到它：
library(lutz)
v <- tz_lookup_coords(lat = dt$lat, lon = dt$lon, method = "accurate")
v1<-as.data.frame(v)
输出：
[1] "America/Bahia" "Etc/GMT+3" "Etc/GMT+3" "Etc/GMT+3" "Etc/GMT+3" "Etc/GMT+3"
但是使用此输出，我不知道如何转换时区。
我想过要做这样的事情：
v1$tzone <- NA
v1[v1$v == "America/Bahia", "tzone"] <- "+3"
v1[v1$v == "America/Sao_Paulo", "tzone"] <- "+3"
v1[v1$v == "Etc/GMT+2", "tzone"] <- "+2"
v1[v1$v == "Etc/GMT+3", "tzone"] <- "+3"
if (v1$tzone == "+3" ) {
v1$timeBR <- NA
v1$timeBR <- strptime(v1$time, format = "%Y-%m-%d %H:%M:%S")
v1$timeBR <- v1$timeBR -3*3600 #creating a column corresponding to local Brazilian time (UTC -3)
v1$hourBR <- as.POSIXlt(v1$timeBR)$hour
v1 <- v1[!is.na(v1$timeBR),]
}
#But the function not works (I dont know do functions), would gonna be better one function with the two condition +3 and +2
有建议：
#t it is the original data
head(t$time)
[1] 2017-10-16 17:01:00 2017-10-16 18:35:22 2017-10-16 20:38:54 2017-10-16 21:27:27 2017-10-16 21:43:20
[6] 2017-10-16 23:24:46
class(t$time)
[1] "factor"
date2<-t$time
class(date2)
[1] "factor"
date2<- as.character(t$time)
class(date2)
[1] "character"
head(date2)
[1] 2017-10-16 17:01:00 2017-10-16 18:35:22 2017-10-16 20:38:54 2017-10-16 21:27:27 2017-10-16 21:43:20
[6] 2017-10-16 23:24:46
t[, date2 := as.POSIXct(date2, format = "%Y-%m-%d %H:%M:%S", tz = "GMT")][,
timezone := tz_lookup_coords(lat = lat, lon = long, method = "accurate")][,
new_time := map2(.x = date2, .y = timezone,
.f = function(x, y) {with_tz(time = x, tzone = y)})][]
Error in `:=`(date2, as.POSIXct(date2, format = "%Y-%m-%d %H:%M:%S", tz = "GMT")) :
Not possible found the function ":="
有人知道该怎么做？谢谢
我认为这就是您想要的。我首先创建了一个日期对象。然后，在尝试时，我用tz_lookup_coords()搜索了时区。然后，我使用了with_tz()，它获得了另一个时区中的日期时间。请注意，new_time是str(dt)所指示的列表。
library(data.table)
library(lutz)
library(purrr)
library(lubridate)
dt[, date := as.POSIXct(date, format = "%Y-%m-%d %H:%M:%S", tz = "GMT")][,
timezone := tz_lookup_coords(lat = lat, lon = long, method = "accurate")][,
new_time := map2(.x = date, .y = timezone,
.f = function(x, y) {with_tz(time = x, tzone = y)})][]
# date lat long timezone new_time
#1: 2018-01-16 22:02:37 -54.5010 -25.0433 Etc/GMT+2 2018-01-16 20:02:37
#2: 2018-01-16 22:54:00 -54.5246 -25.0929 Etc/GMT+2 2018-01-16 20:54:00
#3: 2018-01-16 23:08:38 -54.5285 -25.0832 Etc/GMT+2 2018-01-16 21:08:38
#str(dt)
#Classes ‘data.table’ and 'data.frame': 3 obs. of 5 variables:
# $ date : POSIXct, format: "2018-01-16 22:02:37" "2018-01-16 22:54:00" "2018-01-16 23:08:38"
# $ lat : num -54.5 -54.5 -54.5
# $ long : num -25 -25.1 -25.1
# $ timezone: chr "Etc/GMT+2" "Etc/GMT+2" "Etc/GMT+2"
# $ new_time:List of 3
# ..$ : POSIXct, format: "2018-01-16 20:02:37"
# ..$ : POSIXct, format: "2018-01-16 20:54:00"
# ..$ : POSIXct, format: "2018-01-16 21:08:38"