Downloading FIA data and getting it into R

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.

## 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'))

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'))

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, and 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)