Adds a trend variable to a data set

This function adds a column to a dataset, running from 1 to the length of the data set. If the data set is segmented using the group_by function, a column is added for every subset.

add_trend(av_state, subset_id = 1, varname = "index", log_level = 0)

Arguments

av_state	an object of class av_state
subset_id	either an integer subset index or the the value for the id_field column that was used in the group_by function. The subset_id argument is required if the data set is grouped into multiple data sets (i.e., if the group_by function was used), in which case the function works on the specified data subset.
varname	the name of the newly created indexing column. Will be postfixed with underscores if the column already exists
log_level	sets the minimum level of output that should be shown (a number between 0 and 3). A lower level means more verbosity. Specify a log_level of 3 to hide messages about the columns being added.

Examples

# NOT RUN {
av_state <- load_file("../data/input/pp1 nieuw compleet.sav")
av_state <- add_trend(av_state)
column_names_output(av_state)
av_state$data[[1]][c('index','index2')]
# }