add_duration            Add time spent on a visit in seconds
add_next_visit          Add the next visit as a new column
add_panelist_data       Add panelist features to tracking data
add_previous_visit      Add the previous visit as a new column
add_referral            Add social media referrals as a new column
add_session             Add a session variable
add_title               Download and add the "title" of a URL
audience_incidence      Create incidence matrix for two-mode networks
                        including audiences
audience_network        Create audience networks
bakshy                  Bakshy Top500 Ideological alignment of 500
                        domains based on facebook data
classify_visits         Classify visits by matching to a list of
                        classes
create_urldummy         Create an urldummy variable from a data.table
                        object
deduplicate             Deduplicate visits
domain_list             Domain list classification of domains into
                        news,portals, search, and social media
drop_query              Drop the query and fragment from URL
extract_domain          Extract the domain from URL
extract_host            Extract the host from URL
extract_path            Extract the path from URL
isolation_index         Isolation Index
news_types              News Types
print.wt_dt             Print web tracking data
sum_activity            Summarize activity per person
sum_durations           Summarize visit duration by person
sum_visits              Summarize number of visits by person
summary.wt_dt           Summary function for web tracking data
testdt_survey_l         Test survey
testdt_survey_w         Test survey
testdt_tracking         Test data
vars_exist              Check if columns are present
wt_dt                   An S3 class, based on data.table, to store web
                        tracking data
