Most data operations are useful when done on groups defined by variables
in the dataset. The group_by
function takes an existing table (or
svy_table) and converts it to a grouped version, where operations are
performed "by group".
.data | A tbl |
---|---|
... | variables to group by. All tbls accept variable names, some will also accept functions of variables. Duplicated groups will be silently dropped. |
add | By default, when |
.dots | Used to work around non-standard evaluation. See
|
See group_by
for more information about grouping
regular data tables.
On tbl_svy
objects, group_by
sets up the object for
operations similar to those allowed in svyby
.
group_by
for information about group_by on normal data tables.
# Examples of svy_tbl group_by library(survey) data(api) dstrata <- apistrat %>% as_survey_design(strata = stype, weights = pw) %>% group_by(stype) dstrata %>% summarise(api_diff = survey_mean(api00 - api99))#> # A tibble: 3 × 3 #> stype api_diff api_diff_se #> <fct> <dbl> <dbl> #> 1 E 38.6 2.76 #> 2 H 8.46 3.41 #> 3 M 26.4 3.05