A Report Generated by knitr

This report is automatically generated with the R package knitr (version `1.5`) .

    # Chapter 6 - Going on a Date with R Working with Dates
    xd <- as.Date("2012-07-27")
    xd

    ## [1] "2012-07-27"

    str(xd)

    ##  Date[1:1], format: "2012-07-27"

    weekdays(xd)

    ## [1] "Friday"

    xd + 7

    ## [1] "2012-08-03"

    xd + 0:6

    ## [1] "2012-07-27" "2012-07-28" "2012-07-29" "2012-07-30" "2012-07-31" "2012-08-01"
    ## [7] "2012-08-02"

    weekdays(xd + 0:6)

    ## [1] "Friday"    "Saturday"  "Sunday"    "Monday"    "Tuesday"   "Wednesday" "Thursday"

    startDate <- as.Date("2012-01-01")
    ## xm <- seq(startDate, by='2 months', length.out=6)
    xm

    ## Error: object 'xm' not found

    months(xm)

    ## Error: object 'xm' not found

    quarters(xm)

    ## Error: object 'xm' not found

    Sys.localeconv()

    ##     decimal_point     thousands_sep          grouping   int_curr_symbol   currency_symbol
    ##               "."                ""                ""             "GBP"               "£"
    ## mon_decimal_point mon_thousands_sep      mon_grouping     positive_sign     negative_sign
    ##               "."               ","            "\003"                ""               "-"
    ##   int_frac_digits       frac_digits     p_cs_precedes    p_sep_by_space     n_cs_precedes
    ##               "2"               "2"               "1"               "0"               "1"
    ##    n_sep_by_space       p_sign_posn       n_sign_posn
    ##               "0"               "3"               "3"

    as.Date("27 July 2012", format = "%d %B %Y")

    ## [1] "2012-07-27"

    as.Date("27/7/12", format = "%d/%m/%y")

    ## [1] "2012-07-27"

    # Adding Time Information to Dates
    apollo <- "July 20, 1969, 20:17:39"
    apollo.fmt <- "%B %d, %Y, %H:%M:%S"
    xct <- as.POSIXct(apollo, format = apollo.fmt, tz = "UTC")
    xct

    ## [1] "1969-07-20 20:17:39 UTC"

    format(xct, "%d/%m/%y")

    ## [1] "20/07/69"

    format(xct, "%S minutes past %I %p, on %d %B %Y")

    ## [1] "39 minutes past 08 PM, on 20 July 1969"

    # Performing Operations on Dates and Times Addition and subtraction
    24 * 60 * 60

    ## [1] 86400

    xct + 7 * 86400

    ## [1] "1969-07-27 20:17:39 UTC"

    xct + 3 * 60 * 60

    ## [1] "1969-07-20 23:17:39 UTC"

    xct - 7 * 86400

    ## [1] "1969-07-13 20:17:39 UTC"

    as.Date(xct) - 7

    ## [1] "1969-07-13"

    ## Comparison of dates
    Sys.time()

    ## [1] "2014-05-13 15:05:36 BST"

    Sys.time() < xct

    ## [1] FALSE

    dec.start <- as.POSIXct("1950-01-01")
    ## dec <- seq(dec.start, by='10 years', length.out=4)
    dec

    ## Error: object 'dec' not found

    dec > xct

    ## Error: object 'dec' not found

    ## Extraction
    xlt <- as.POSIXlt(xct)
    xlt

    ## [1] "1969-07-20 20:17:39 UTC"

    xlt$year

    ## [1] 69

    xlt$mon

    ## [1] 6

    unclass(xlt)

    ## $sec
    ## [1] 39
    ##
    ## $min
    ## [1] 17
    ##
    ## $hour
    ## [1] 20
    ##
    ## $mday
    ## [1] 20
    ##
    ## $mon
    ## [1] 6
    ##
    ## $year
    ## [1] 69
    ##
    ## $wday
    ## [1] 0
    ##
    ## $yday
    ## [1] 200
    ##
    ## $isdst
    ## [1] 0
    ##
    ## attr(,"tzone")
    ## [1] "UTC"

The R session information (including the OS info, R version and all packages used):

    sessionInfo()

    ## R version 3.0.2 (2013-09-25)
    ## Platform: x86_64-w64-mingw32/x64 (64-bit)
    ##
    ## locale:
    ## [1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252
    ## [3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
    ## [5] LC_TIME=English_United Kingdom.1252
    ##
    ## attached base packages:
    ## [1] stats     graphics  grDevices utils     datasets  methods   base
    ##
    ## other attached packages:
    ##  [1] BiocInstaller_1.12.1 ggplot2_0.9.3.1      reshape2_1.2.2       sos_1.3-8
    ##  [5] brew_1.0-6           stringr_0.6.2        knitr_1.5            plyr_1.8
    ##  [9] Revobase_7.1.0       RevoMods_7.1.0       RevoScaleR_7.1.0     lattice_0.20-27
    ## [13] rpart_4.1-2
    ##
    ## loaded via a namespace (and not attached):
    ##  [1] codetools_0.2-8    colorspace_1.2-4   dichromat_2.0-0    digest_0.6.4
    ##  [5] evaluate_0.5.1     foreach_1.4.1      formatR_0.10       fortunes_1.5-2
    ##  [9] grid_3.0.2         gtable_0.1.2       highr_0.3          iterators_1.0.6
    ## [13] labeling_0.2       MASS_7.3-29        munsell_0.4.2      proto_0.3-10
    ## [17] RColorBrewer_1.0-5 scales_0.2.3       tools_3.0.2

    Sys.time()

    ## [1] "2014-05-13 15:05:37 BST"