Returns the field_period dataset-level metadata key from a survey design
object or a data frame.
Details
Returns the stored field_period only. It never composes a period from
field_start and field_end — use extract_field_dates() for those. On a
data frame the pre-1.2.0 attribute name dates is read as field_period
when no field_period attribute is present. A design object restored from a
file written by surveycore 1.1.0 or earlier reports NA_character_ rather
than failing.
See also
Other metadata:
classify_question_type(),
extract_data_name(),
extract_dataset_metadata(),
extract_field_dates(),
extract_higher_is(),
extract_metadata(),
extract_missing_codes(),
extract_question_preface(),
extract_reverse_coded(),
extract_sata(),
extract_survey_name(),
extract_universe(),
extract_val_labels(),
extract_var_extra(),
extract_var_label(),
extract_var_note(),
extract_vendor(),
infer_question_prefaces(),
set_data_name(),
set_dataset_metadata(),
set_field_dates(),
set_field_period(),
set_higher_is(),
set_missing_codes(),
set_question_preface(),
set_reverse_coded(),
set_sata(),
set_survey_name(),
set_universe(),
set_val_labels(),
set_var_extra(),
set_var_label(),
set_var_note(),
set_vendor(),
survey_metadata(),
survey_weighting_history()
Examples
df <- data.frame(id = 1:5, y = c(2, 4, 3, 5, 1), w = rep(1, 5))
extract_field_period(df)
#> [1] NA
df <- set_field_period(df, "February-March 2026")
extract_field_period(df)
#> [1] "February-March 2026"