The data was manipulated multiple times in R and exported as csv or xlsx format.
In excel the original date looks normal: (time = c("2016-08-10 09:30:01", "2016-08-11 09:30:01", "2016-08-12 09:30:01", "2016-08-13 09:30:01", "2016-08-14 09:30:01", "2016-08-15 09:30:01"), but after reading into R again and plotted in graphs, it got distorted and looks like 0001-01-16, 0001-01-16, 0001-02-16 on the graph.
How could I change the date and make it normal? Thank you very much.
If you parse this input correctly, things should work. Here we use anytime() from the anytime package which is robust to input types and formats:
R> library(anytime)
R> time <- c("2016-08-10 09:30:01", "2016-08-11 09:30:01", "2016-08-12 09:30:01",
+ "2016-08-13 09:30:01", "2016-08-14 09:30:01", "2016-08-15 09:30:01")
R> anytime(time)
[1] "2016-08-10 09:30:01 CDT" "2016-08-11 09:30:01 CDT" "2016-08-12 09:30:01 CDT"
[4] "2016-08-13 09:30:01 CDT" "2016-08-14 09:30:01 CDT" "2016-08-15 09:30:01 CDT"
R>
These are now POSIXct objects so you can use them to plot, analyse, summarize, ...
R> diff(anytime(time))
Time differences in days
[1] 1 1 1 1 1
R>
The comment by @42 is still correct though: your question is little lacking in specifics and detail.