[R] Date read correctly from CSV, then reformatted incorrectly by R
prmonk @end|ng |rom gm@||@com
Sat Nov 20 18:48:51 CET 2021
Thanks Eric & Jeff.
I'll certainly read up on lubridate, and the posting guide (again)
(this should be in plain text).
CSV extract below...
Buffer 28/10/2016 19/11/2016 31/12/2016 16/01/2017 05/03/2017
100 2.437110889 -8.69674895 3.239299816 2.443183304 2.346743827
200 2.524329899 -7.688862068 3.386811734 2.680347706 2.253885237
300 2.100784256 -8.059855835 3.143786507 2.615152896 2.015645973
400 1.985608385 -10.6707206 2.894572791 2.591925038 2.057913137
500 1.824982163 -9.122519736 2.560350727 2.372226799 1.995863839
On Sat, 20 Nov 2021 at 17:08, Philip Monk <prmonk using gmail.com> wrote:
> Simple but infuriating problem.
> Reading in CSV of data using :
> # CSV file has column headers with date of scene capture in format dd/mm/yyyy
> # check.names = FALSE averts R incorrectly processing dates due to '/'
> data <- read.csv("C:/R_data/Bungala (b2000) julian.csv", check.names = FALSE)
> # Converts data table from wide (many columns) to long (many rows) and creates the new object 'data_long'
> # Column 1 is the 'Buffer' number (100-2000), Columns 2-25 contain monthly data covering 2 years (the header row being the date, and rows 2-21 being a value for each buffer).
> # Column headers for columns 2:25 are mutated into a column called 'Date', values for each buffer and each date into the column 'LST'
> data_long <- data %>% pivot_longer(cols = 2:25, names_to = "Date", values_to = "LST")
> # Instructs R to treat the 'Date' column data as a date
> data_long$Date <- as.Date(data_long$Date)
> Using str(data), I can see that R has correctly read the dates in the format %d/%m/%y (e.g. 15/12/2015) though has the data type as chr.
> Once changing the type to 'Date', however, the date is reconfigured. For instance, 15/01/2010 (15 January 2010), becomes 0015-01-20.
> I've tried ```data_long$Date <- as.Date(data_long$Date, format = "%d/%m.%y")```, and also ```tryformat c("%d/%m%y")```, but either the error persists or I get ```NA```.
> How do I make R change Date from 'chr' to 'date' without it going wrong?
> Suggestions/hints/solutions would be most welcome. :)
> Thanks for your time,
> Part-time PhD Student (Environmental Science)
> Lancaster University, UK.
> I asked a question a few weeks ago and put together the answer I needed from the responses but didn't know how to say thanks on this list. So, thanks Andrew Simmons, Bert Gunter, Jeff Newmiller and Daniel Nordlund!
More information about the R-help