Extract month from ISO-8601 format date using R-CodePudding

I have a dataframe with date column (its data type is factor) in format as follows:

uid             date
<int>          <fctr>
2970134  2019-12-31T17:05:00Z           
2970204  2019-12-31T23:14:00Z           
2970345  2020-01-01T11:00:00Z

I've converted them to the format 2019-12-31T00:00:00 0800 with code below:

data$date <- format(as.POSIXct(data$date), format='%Y-%m-%dT%H:%M:%S%z')

My question is I how to could I extract month from it? I tried with format(as.POSIXct(data$date_single, format='%Y-%m-%dT%H:%M:%S%z'),format='%m') but it returns NAs. Thanks.

CodePudding user response：

require(tidyverse)    
require(lubridate) # Package for date and time manipulation

data %>%  
  mutate(month = month(date))

CodePudding user response：

You have a small logic error. You take your input data and parse it -- so far, so good:

> v <- c("2019-12-31T17:05:00Z", "2019-12-31T23:14:00Z", "2020-01-01T11:00:00Z")
> pt <- as.POSIXct(v)
> pt
[1] "2019-12-31 CST" "2019-12-31 CST" "2020-01-01 CST"
>

Now that you have date(time) information, you can format() or strftime() as you like:

> strftime(pt, "%m")
[1] "12" "12" "01"
> strftime(pt, "%b")
[1] "Dec" "Dec" "Jan"
> strftime(pt, "%B")
[1] "December" "December" "January" 
>

Converting from character to int is also easy. Note that all this was done with base R without any additional packages.