comtradr 0.3.0

NEW FEATURES

Function ct_register_token() now checks if the provided token is recognized by the official API and only grants “premium” credentials if it is (#34).
Passing an API token string to ct_register_token() now properly bumps the hourly rate limit up to 10,000 (#21).
In func ct_search(), passing a character vector of long-form commodity descriptions to arg commod_codes will now throw an error prior to making an API call, which would fail (#24).
Update the country package data, to stay up to date with the reporter/partner country table that Comtrade is using. This is an update to the file inst/extdata/country_table.rda. (#29).
In func ct_search(), improve error messaging when an input country is invalid. (#31).
In func ct_search(), fix bug in which running queries using the SITCrev2 commodity type was returning raw HTML (as opposed to json data). (#27).
In func ct_country_lookup(), remove NA inputs from multi-country lookups (previously NA was being stringified and included in the pipe-separated regex lookup).

Modifications to ct_search() to allow for pulling all monthly data for an entire year in a single query (#14)
For function ct_search(), expanded the valid input types for args start_date and end_date (#10).

ct_search() now supports all commodity classifications offered by UN Comtrade (#16).
The updates generated by function ct_update_databases() are now properly preserved between R sessions (#11).
Passing "services" to arg type within function ct_search() now uses commodity classification EB02 by default (previously this would throw an error, fixes #6).
When using commodity classification EB02 within function ct_search(), passing "TOTAL" to arg commod_codes no longer returns zero results (#7).
ct_commodity_lookup() no longer returns zero results when passing all caps input to arg search_terms (#9).

Eliminated functions ct_commodities_table and ct_countries_table.
Added new functions ct_update_databases, ct_use_pretty_cols, ct_commodity_db_type, ct_register_token, ct_get_reset_time, ct_get_remaining_hourly_queries.
Renamed functions: commodity_lookup is now ct_commodity_lookup, country_lookup is now ct_country_lookup.
The commodity and country reference tables are now saved as cached package data, and accessed by comtradr functions when necessary. This replaces the need for functions ct_commodities_table and ct_countries_table.
Reorder function arguments within function ct_search.
Changed some function argument names to ensure snake_case is being used throughout the package.
ct_search now returns a data frame, as opposed to a list.

Added a vignette directory, with an “Intro to comtradr” vignette.
API requests are now throttled based on the rate limits imposed by the UN Comtrade.
Added function for setting a valid API key/token (ct_register_token).
Appending API metadata to each returned data frame as attributes (url of the API call, date-time of the query, duration of the query in seconds).
Added package level man page.
Now using native R errors/warnings, as opposed to nesting API status codes in a returned list.
Imports changes: remove dplyr, add magrittr and purrr.
Expand and improve test coverage via testthat.

The issues related to type-safety in function commodity_lookup have been fixed by importing purrr and using purrr::map in place of sapply. This fixes issue #2 and issue #3.

commodity_lookup(): Expanded function to accept multiple commodities or commodity codes (as either character vector or numeric vector). Also added argument “return_char” that allows the user to specify list output or char vector output, and argument “return_code” that specifies output of commodity descriptions or commodity codes.