Question

I have the following data

>d
2010-07-02
>t
835

I issue the following command

>dt<-paste(d,t)
>dt
"2010-07-02 835" 

i then issue the following command, and it returns NA as below:

>dtt<-as.POSIXlt(strptime(dt,'%Y-%m-%d %H%M'))
>dtt
 NA

so I made the following change

>t=1001

and now when I run
dt followed by dtt, it works fine, returning

dtt
“2010-07-02 10:01:00”

so, it seems to me that it is having a problem with the first digit of the hour being a 0, which is why when HHMM is less than 1000, it generates NA. can anyone please suggest how I fix this. thanks!

Answer 1

Use sprintf to format your time string before you pass it to as.POSIXlt:

d <- "2010-07-02"
h <- 835

dtt <- sprintf("%s %04d", d, h)
as.POSIXlt(dtt, format="%Y-%m-%d %H%M")
[1] "2010-07-02 08:35:00"

The string "%s %04d" tells sprintf to concatenate d as a string (%s) and h as a fixed width string of length 4, with leading zeroes (%04d).