Obtaining an API key is easy and free.
Pulling data from the US Energy Information Administration (EIA) API requires a registered API key. A key can be obtained at no cost here.
A valid email and agreement to the API Terms of Service is required to obtain a key.
It is important to store your API key somewhere secure. Do not commit
it to a repository or otherwise share it. For example, you can store it
.Renviron file. This is the recommended method for
simplicity and persistent availability. If you do this, you do not have
to do anything else. Other approaches that allow for emphemeral storage
or overriding a default key with another key are outlined below.
You can always provide the
key argument to every API
function call, but you do not have to. There are environmental getter
and setter functions available. Whichever method you use to set your key
eia API functions can get the key
eia_set_key() gives you the option of storing your key
in any of three places via the
store = "env": the package environment that is created when the package is loaded (default method)
store = "options": in the global
store = "sysenv": as a system environment variable via
The last two options require the name-value pair to be named
EIA_KEY = "yourkey". These three options also are the order
of precedence if you do not specify the
This setup also allows you to store a key that will override another
key. This is because
eia_get_key() checks these three
storage methods in this order and stops as soon as it finds a key. If
you need it to check a specific location, you can specify
As an example, if the key already exists in the system environment
and you plan to pass
key to functions explicitly, you could
start as follows:
If you need to set it, you can do so as follows.
API functions in
no arguments as the default value of their
checking in the order shown above for an existing key. This way you do
not need to repeatedly provide it.
Note that despite the name and behavior, storing an environment
Sys.setenv() (and thus
eia_set_key(key, store = "sysenv")) is not persistent; the
key is lost when the R session terminates, just as it is with the other
two session-based options. If you want a persistent key, you must
manually add your key somewhere like
.Renviron. In that
cases, you never need
eia_get_key() will retrieve the
environment variable. See the package documentation for more details on
In this and subsequent vignettes, you will not see a key being set because it is already an environment variable. You will also not see it used explicitly by any functions because the default behavior is to look up the key in the environment.
The EIA API can of course impose its own rate-limiting and other
limitations on usage by a given API key. If you use the API improperly
or otherwise violate any Terms of Service, the EIA may withdraw your API
access. However, the
eia package also helps prevent
accidental overuse by having default settings that limit the potential
for making unnecessary API calls. It does this in two ways, both of
which allow optional configuration:
By default the
eia package prevents you from
accidentally making too many requests too quickly, but it also offers
All functions in
eia that make API calls use memoization
by default. They will not make the same API call twice in one R session.
A call is made once and the result is cached. Calling the same function
with the identical arguments again will only returned the cached
This approach limits the potential for accidentally using the EIA API
more than necessary. This is fine for most uses cases. However, if you
use your API key to access data that is updated very often, or you have
a long-running R process such as a Shiny app on a server that may need
to periodically update the data associated with a specific API call, you
cache = FALSE.
Run this example of the same request made with and without memoization. You will notice the cached result by the immediate return.
Results are cached in memory for the duration of the R session, but you can clear the cache at any time.
This allows you to update the cached result. You can reset the cache for only specific endpoints using the following functions.
Regardless of overall rate limiting imposed by the EIA API, the
eia package sets a minimum wait time of one second between
successive API calls. In most cases this is an irrelevant safeguard.
eia functions make a single API call and requests for
data often take a full second anyway once you factor in the subsequent
data manipulation in R.
However, there are cases where you might want to make multiple calls back to back programmatically and perhaps you are initially unsure how many requests will be made or how quickly these requests may execute. The default minimum wait between API calls is a precaution that helps you be a good neighbor.
You can turn this off with
options() if not needed; for
example, a case where you know that your API calls will be small in
number and you have no reason to be concerned about exceeding the
request limits associated with your API key. The default requires you to
make an active decision about how to use the API with your own key and
API limits in mind.