Download data
The first step to using rFIA is to download subsets of
the FIA Database. The easiest way to accomplish this is using
getFIA(). Using one line of code, you can download state
subsets of the FIA Database, load data into your R environment, and
optionally save those data to a local directory for future use.
Alternatively, you may also choose to download subsets as .csv files
from the FIA
DataMart and load into R using readFIA().
library(rFIA)
# Download the state subset or Connecticut (requires an internet connection)
# Save as an object to automatically load the data into your current R session!
ct <- getFIA(states = 'CT', dir = '/path/to/save/data')
# Get multiple states worth of data (not saved since 'dir' is not specified)
northEast <- getFIA(states = c('ME', 'NH', 'VT', 'NY', 'CT', 'MA', 'RI'))You can also download REFERENCE tables listed on the FIA
DataMart by specifying states = 'REF':
# Get the forest type and forest type group reference tables
ref <- getFIA(states = 'ref', tables = c('FOREST_TYPE', 'FOREST_TYPE_GROUP'))If you are downloading a large amount of data (e.g., the entire
eastern US), you may not want to load it all into R immediately. In this
case, specify load=FALSE in the call to
getFIA(). This will ensure all data is download and saved
to disk without maxing out your RAM. For more on ‘big data’ management,
check out our larger than RAM
methods.
Load data into R
If you used getFIA to download data in your current R
session, then the database is likely automatically loaded into your
current R session (unless load=FALSE). Theoretically, we
could use getFIA to re-download FIA data every time you
want to use, but that would be very inefficient. Instead, we
recommend you save downloaded FIA data using the dir
argument in getFIA (automatically saves on download) or
using writeFIA (saves any in-memory
FIA.Database). Once data are saved on disk, you can quickly
re-load them into R using readFIA:
## Load FIA Data from a local directory
db <- readFIA('/path/to/your/directory/')Loading multiple states
Need to load multiple state subsets of FIA data for regional
analyses? No problem! Using getFIA(), specify mutiple state
abbreviations in the states argument
(e.g. states = c('MI', 'IN', 'WI', 'IL')). Alternatively,
download individual states seperately and save them to the same
directory. When multiple state subsets of data are loaded into R using
getFIA() or readFIA(), subsets will be merged
into a single FIA.Database object. This will allow you to
use other rFIA functions to produce estimates for areas
which straddle state boundaries!
Conveniently, you can selectively read state subsets from a directory
containing multiple states worth of data using readFIA().
For example, lets say we previously used getFIA() to
download FIA data for Washington, Oregon, and Idaho. We saved all this
data to same directory, and hence pointing readFIA() to
this directory will automatically load and merge all states. But what if
we just want to load the data for Washington? Easy, use the
states argument in readFIA:
# Download data for PNW states, but don't load the data yet
getFIA(states = c('WA', 'OR', 'ID'),
dir = 'path/to/my/directory/',
load = FALSE)
# A simple call to readFIA will load and merge all states
allStates <- readFIA(dir = 'path/to/my/directory/')
# But using the 'states' argument we can select individual states (or groups)
wa <- readFIA(dir = 'path/to/my/directory/', states = 'WA')
# Read WA and OR, but not ID
wa_or <- readFIA(dir = 'path/to/my/directory/', states = c('WA', 'OR'))Given the massive size of the full FIA Database (~50 GB), users are cautioned to only download the subsets containing their region of interest.
Loading specific tables
If you are only interested in loading/downloading a specific table
from the FIA database, simply specify the names of those tables in the
tables argument of readFIA() or
getFIA() (e.g. specify
tables = c('TREE', 'PLOT') for the TREE and PLOT tables).
See the FIA
User Guide for a complete description of the database.
By default, getFIA() and readFIA() only
loads/downloads the portions of the database required to produce
summaries with other rFIA functions
(common = TRUE). This conserves memory on your machine and
speeds download time. If you would like to load/download all available
tables for a state, simple specify common = FALSE in the
call to readFIA() or getFIA().
The FIA.Database object
When FIA data is loaded into R with readFIA() or
getFIA(), those data are stored in an
FIA.Database object. An FIA.Database object is
essentially just a list with each list element corresponding to an
individual FIA table. Accordingly, users can access individual tables
with $, [''], and [['']]
operators:
# Access the TREE, PLOT, and COND tables
# Tree
db$TREE
# Plot
db['PLOT']
# Check spatial coverage of plots held in the database
plotFIA(db)