Package 'openair'

22 drawOpenKeyof this option is to test whether there is a shift in the diurnal profile when GMT and BST hoursare compared. This option is particularly useful with the timeVariation function. For example,close to the source of road vehicle emissions, ‘rush-hour’ will tend to occur at the same local timethroughout the year e.g. 8 am and 5 pm. Therefore, comparing GMT hours with BST hours willtend to show similar diurnal patterns (at least in the timing of the peaks, if not magnitude) whenexpressed in local time. By contrast a variable such as wind speed or temperature should show aclear shift when expressed in local time for BST vs. GMT. In essence, this option when used withtimeVariation may help determine whether the variation in a pollutant is driven by man-madeemissions or natural processes."wd" splits the data by 8 wind sectors and requires a column wd: "NE", "E", "SE", "S", "SW", "W","NW", "N"."ws" splits the data by 8 quantiles of wind speed and requires a column ws."site" splits the data by site and therefore requires a column site.ValueReturns a data frame with a column cond that is defined by type.Author(s)David Carslaw (cutData) and Karl Ropkins (cutDaylight)Examples## split data by day of the weekmydata