seq.POSIXt               package:base               R Documentation

_G_e_n_e_r_a_t_e _R_e_g_u_l_a_r _S_e_q_u_e_n_c_e_s _o_f _D_a_t_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     The method for 'seq' for date-time classes.

_U_s_a_g_e:

     ## S3 method for class 'POSIXt':
     seq(from, to, by, length.out = NULL, along.with = NULL, ...)

_A_r_g_u_m_e_n_t_s:

    from: starting date. Required.

      to: end date. Optional.

      by: increment of the sequence. Optional. See Details.

length.out: integer, optional. desired length of the sequence.

along.with: take the length from the length of this argument.

     ...: arguments passed to or from other methods.

_D_e_t_a_i_l_s:

     'by' can be specified in several ways.

        *  A number, taken to be in seconds.

        *  A object of class 'difftime'

        *  A character string, containing one of '"sec"', '"min"',
           '"hour"', '"day"', '"DSTday"', '"week"', '"month"' or
           '"year"'.  This can optionally be preceded by a (positive or
           negative) integer and a space, or followed by '"s"'.

     The difference between '"day"' and '"DSTday"' is that the former
     ignores changes to/from daylight savings time and the latter takes
     the same clock time each day.  ('"week"' ignores DST, but '"7
     DSTdays"') can be used as an alternative.  '"month"' and '"year"'
     allow for DST.)

     The timezone of the result is taken from 'from': remember than GMT
     does not have daylight savings time.

_V_a_l_u_e:

     A vector of class '"POSIXct"'.

_S_e_e _A_l_s_o:

     'DateTimeClasses'

_E_x_a_m_p_l_e_s:

     ## first days of years
     seq(ISOdate(1910,1,1), ISOdate(1999,1,1), "years")
     ## by month
     seq(ISOdate(2000,1,1), by = "month", length = 12)
     ## quarters
     seq(ISOdate(1990,1,1), ISOdate(2000,1,1), by = "3 months")
     ## days vs DSTdays: use c() to lose the timezone.
     seq(c(ISOdate(2000,3,20)), by = "day", length = 10)
     seq(c(ISOdate(2000,3,20)), by = "DSTday", length = 10)
     seq(c(ISOdate(2000,3,20)), by = "7 DSTdays", length = 4)

