Function reference • regstudies

Classification Functions for classifying codes and calculating scores
`classify_codes()`	Extends the original data with the classification table and keeps data in long format.
`classify_charlson()`	Extends the original data with the classification table and keeps data in long format. Computes classification table and attaches it to original data. Data stays in long format.
`classify_elixhauser()`	Extends the original data with the classification table and keeps data in long format. Computes classification table and attaches it to original data. Data stays in long format.
`read_classes()`	Internal function for providing long classification definitions.
`sum_score()`	Sum scores for each individual. Allows arbitrary number of scores to be calculated using single function call.
Date functions Functions for filtering using datetime variables
`filter_date_in_ival()`	Filtering of datetime data within a time interval. The function finds rows for which `date_var` is within interval created based on `index_date`, `time_before` and `time_after`.
`filter_ival_olap_ival()`	Filtering of date interval data within study interval. Can be used for filtering e.g. for hospital visits, which are date intervals (time periods). The function finds rows for which `ival_var` overlaps with interval created based on `index_date`, `time_before` and `time_after`.
`filter_date_first()`	Get first value based on datetime variable
`filter_date_last()`	Get last value based on datetime variable
`filter_date_nearest()`	Get nearest value based on datetime variable
Helpers and others Functions that are helpful when conducting data analysis
`get_var_types()`	Get variable types
`get_na_vars()`	Function for extracting names of variables which have any NA values
`left_join_replace_na()`	left_join with fill option
`replace_na_by_type()`	Replace NA values as default values based no the type of the variable