The meanings of flags

Steffi LaZerte

2018-10-08

What are flags

The data output of the weather_dl() function include a corresponding _flag column for each data column. These columns are used by ECCC to add notes regarding measurements.

In the weather_dl() function if format = TRUE (the default), data corresponding to flags M, NA, [empty] and L are all replaced with NA.

For example, a sample of unformatted data from Magog station in Quebec looks like:

## # A tibble: 6 x 4
##   station_name `Date/Time` `Total Precip (mm)` `Total Precip Flag`
##   <chr>        <chr>       <chr>               <chr>              
## 1 MAGOG        2017-09     63.0                ^                  
## 2 MAGOG        2017-10     140.8               ^                  
## 3 MAGOG        2017-11     70.0                ^                  
## 4 MAGOG        2017-12     45.7                ^                  
## 5 MAGOG        2018-01     34.6                ^                  
## 6 MAGOG        2018-02     77.2                ^
## # A tibble: 6 x 4
##   station_name `Date/Time` `Snow Grnd Last Day (cm)` `Snow Grnd Last Day Flag`
##   <chr>        <chr>       <chr>                     <chr>                    
## 1 MAGOG        2017-09     0                         ""                       
## 2 MAGOG        2017-10     0                         ""                       
## 3 MAGOG        2017-11     0                         ""                       
## 4 MAGOG        2017-12     10                        ""                       
## 5 MAGOG        2018-01     2                         ""                       
## 6 MAGOG        2018-02     0                         ""

In this output, you can see two flags: ^ in Total Precip and M in Snow Grnd Last Day

This same sample, formatted looks like:

## # A tibble: 6 x 5
##   date       total_precip total_precip_flag snow_grnd_last_day snow_grnd_last_day_flag
##   <date>            <dbl> <chr>                          <dbl> <chr>                  
## 1 2017-09-01         63   ^                                  0 ""                     
## 2 2017-10-01        141.  ^                                  0 ""                     
## 3 2017-11-01         70   ^                                  0 ""                     
## 4 2017-12-01         45.7 ^                                 10 ""                     
## 5 2018-01-01         34.6 ^                                  2 ""                     
## 6 2018-02-01         77.2 ^                                  0 ""

As you can see, we still have the two flags, but the missing data flag (M) is now replaced with NA. The other flag ^ is not, as it indicates that “The value displayed is based on incomplete data” (see below).

Flags

The flags index can be accessed through the built in data frame: flags

code meaning
E Estimated
M Missing
NA Not Available
Date/Time Year
A Accumulated
C Precipitation occurred, amount uncertain
F Accumulated and estimated
L Precipitation may or may not have occurred
N Temperature missing but known to be > 0
S More than one occurrence
T Trace
Y Temperature missing but known to be < 0
[empty] No data available
^ The value displayed is based on incomplete data
Data that is not subject to review by the National Climate Archives
B More than one occurrence and estimated