date

问题 I have a column in a dataframe that contains the day number ( 0 through 6, 0=Sunday, 1=Monday, etc) and I need to convert that to the day name. How can I do this? Sample data: df <- data.frame(day_number=0:6) 回答1: Simple way with dplyr. library(dplyr) df <- data.frame(day_number=0:6) df$day_number <- recode(df$day_number, "0"="Sunday", "1"="Monday", "2"="Tuesday", "3"="Wednesday", "4"="Thursday", "5"="Friday", "6"="Saturday") 回答2: Treat the column as a factor with day name as label: x <- data

问题 I have a column in a dataframe that contains the day number ( 0 through 6, 0=Sunday, 1=Monday, etc) and I need to convert that to the day name. How can I do this? Sample data: df <- data.frame(day_number=0:6) 回答1: Simple way with dplyr. library(dplyr) df <- data.frame(day_number=0:6) df$day_number <- recode(df$day_number, "0"="Sunday", "1"="Monday", "2"="Tuesday", "3"="Wednesday", "4"="Thursday", "5"="Friday", "6"="Saturday") 回答2: Treat the column as a factor with day name as label: x <- data

问题 How Can I get the date time in unix time as byte array which should fill 4 bytes space in Java? Something like that: byte[] productionDate = new byte[] { (byte) 0xC8, (byte) 0x34, (byte) 0x94, 0x54 }; 回答1: First: Unix time is a number of seconds since 01-01-1970 00:00:00 UTC. Java's System.currentTimeMillis() returns milliseconds since 01-01-1970 00:00:00 UTC. So you will have to divide by 1000 to get Unix time: int unixTime = (int)(System.currentTimeMillis() / 1000); Then you'll have to get

问题 How Can I get the date time in unix time as byte array which should fill 4 bytes space in Java? Something like that: byte[] productionDate = new byte[] { (byte) 0xC8, (byte) 0x34, (byte) 0x94, 0x54 }; 回答1: First: Unix time is a number of seconds since 01-01-1970 00:00:00 UTC. Java's System.currentTimeMillis() returns milliseconds since 01-01-1970 00:00:00 UTC. So you will have to divide by 1000 to get Unix time: int unixTime = (int)(System.currentTimeMillis() / 1000); Then you'll have to get

问题 Can we somehow convert dates such as "November 2017", "December 2017" to date? I tried to import csv data, but received factor columns. I tried the following code, but was not successful. as.POSIXct(as.character(dat$Date), format = "%B %Y") 回答1: A quick solution from lubridate package dmy(paste("01", dat$Date)) 回答2: A POSIXct date needs the day of the month to be complete and valid. You can add it to the date strings, then use the format "%B %Y %d" e.g. : as.POSIXct(paste(as.character(dat

问题 How can I calculate the day of month in PHP with giving month, year, day of week and number of week. Like, if I have September 2013 and day of week is Friday and number of week is 2, I should get 6. (9/6/2013 is Friday on the 2nd week.) 回答1: One way to achieve this is using relative formats for strtotime(). Unfortunately, it's not as straightforward as: strtotime('Friday of second week of September 2013'); In order for the weeks to work as you mentioned, you need to call strtotime() again

问题 How can I calculate the day of month in PHP with giving month, year, day of week and number of week. Like, if I have September 2013 and day of week is Friday and number of week is 2, I should get 6. (9/6/2013 is Friday on the 2nd week.) 回答1: One way to achieve this is using relative formats for strtotime(). Unfortunately, it's not as straightforward as: strtotime('Friday of second week of September 2013'); In order for the weeks to work as you mentioned, you need to call strtotime() again

问题 I'm trying to use joda-time to parse a date string of the form YYYY-MM-DD . I have test code like this: DateTimeFormatter dateDecoder = DateTimeFormat.forPattern("YYYY-MM-DD"); DateTime dateTime = dateDecoder.parseDateTime("2005-07-30"); System.out.println(dateTime); Which outputs: 2005-01-30T00:00:00.000Z As you can see, the DateTime object produced is 30 Jan 2005 , instead of 30 July 2005 . Appreciate any help. I just assumed this would work because it's one of the date formats listed here.

问题 I'm trying to use joda-time to parse a date string of the form YYYY-MM-DD . I have test code like this: DateTimeFormatter dateDecoder = DateTimeFormat.forPattern("YYYY-MM-DD"); DateTime dateTime = dateDecoder.parseDateTime("2005-07-30"); System.out.println(dateTime); Which outputs: 2005-01-30T00:00:00.000Z As you can see, the DateTime object produced is 30 Jan 2005 , instead of 30 July 2005 . Appreciate any help. I just assumed this would work because it's one of the date formats listed here.

问题 I'm trying to use joda-time to parse a date string of the form YYYY-MM-DD . I have test code like this: DateTimeFormatter dateDecoder = DateTimeFormat.forPattern("YYYY-MM-DD"); DateTime dateTime = dateDecoder.parseDateTime("2005-07-30"); System.out.println(dateTime); Which outputs: 2005-01-30T00:00:00.000Z As you can see, the DateTime object produced is 30 Jan 2005 , instead of 30 July 2005 . Appreciate any help. I just assumed this would work because it's one of the date formats listed here.