Censored observations are identified in swmpr objects using the CDMO flags -4 or -5, indicating outside the low or high sensor range, respectively. Additional codes are identified including A (-2007) or SUL (2007-) for above and B (-2007), SBL (2007-), SCB (2007-, calculated) for below detection limits. The QAQC columns are searched for all parameters and replaced with the appropriate value indicating the detection limit as defined by flag_type
. The default argument flag_type = 'both'
will recode the QAQC columns as -1, 0, or 1 indicating below, within, or above the detection limit. Setting flag_type = 'below'
or 'above'
will convert the columns to TRUE
/FALSE
values indicating observations beyond the detection limit (either above or below, TRUE
) or within the normal detection range FALSE
.
The output includes additional columns similar to those for QAQC flags, such that the column names for censored flags include a c_
prefix before the parameter name. Note that the function will of course not work if already processed with qaqc
. QAQC columns are retained for additional processing.
The user should refer to the metadata or visually examine the observed data to identify the actual limit, which may change over time.