check_for_matching_geolocation_files: Checks that every MODIS cloud project HDF has a matching MOD03 file

Description

Each MOD35_L2 cloud mask product file requires a corresponding MOD03 geolocation file to be successfully processed with the MRTSwath tool.

Usage

check_for_matching_geolocation_files(moddir = getwd(), modtxt = "MOD35_L2", geoloctxt = "MOD03", return_geoloc = FALSE, return_product = FALSE)

Arguments

moddir

the string describing the directory containing the MOD35_L2 and MOD03 files; both must be in the same directory. Default: getwd(), which gives the present working directory.

modtxt

the text string indicating which HDF files are the MODIS cloud product (or hypothetically, other product). Default: MOD35_L2 (MODIS cloud mask product)

geoloctxt

the text string indicating which HDF files are the MODIS geolocation files (or hypothetically, another set of files). Default: MOD03

return_geoloc

if TRUE, return the list of unmatched geolocation files (e.g. MOD03 or MYD03)

return_product

if TRUE, return the list of unmatched product files (e.g. MOD35_L2 or MYD35_L2 or MOD06_L2 or MYD06_L2)

Value

data.frame of matching files; or a list of non-matching files, if return_geoloc or return_product are TRUE.

Details

MRTSwath is the MRT (MODIS Reprojection Tool) for the MODIS level 1 and level 2 products (cloud mask is level 2, I think).

E.g. this cloud mask file:

MOD35_L2.A2012001.0420.005.2012001131638.hdf

...goes with this corresponding geolocation file:

MOD03.A2012001.0420.005.2012001104706.hdf

...which is a large file (~30 MB) containing detailed information on the position, tilt, etc. of the MODIS satellite.

For whatever reason, even a search done at the same time at http://reverb.echo.nasa.gov/reverb/#utf8= will not necessarily return the same number of MOD35_L2 and MOD03 files. MRTSwath tool needs one of each, however.

Examples

Run this code

# Check your working directory
moddir = getwd()

# Here are some example MODIS files in modiscloud/extdata/
# Code excluded from CRAN check because it depends on modiscdata
## Not run: 
# library(devtools)
# # The modiscdata (MODIS c=cloud data=data) package is too big for CRAN (60 MB); so it is available on github:
# # https://github.com/nmatzke/modiscdata
# # If we can't get install_github() to work, try install_url():
# # install_github(repo="modiscdata", username="nnmatzke")
# install_url(url="https://github.com/nmatzke/modiscdata/archive/master.zip")
# library(modiscdata)
# moddir = system.file("extdata/2002raw/", package="modiscdata")
# 
# # You need to have some e.g. MOD files in it (from the MODIS-TERRA platform)
# # (*won't* work with the default files stored in modiscloud/extdata/2002raw/)
# list.files(path=moddir, pattern="MOD")
# 
# # This directory actually has MYD files (from the MODIS-AQUA platform)
# # (*will* work with the default files stored in modiscloud/extdata/2002raw/)
# list.files(path=moddir, pattern="MYD")
# 
# # Check for matches (for MODIS-TERRA platform)
# # (*won't* work with the default files stored in modiscloud/extdata/2002raw/)
# check_for_matching_geolocation_files(moddir=moddir, modtxt="MOD35_L2", geoloctxt="MOD03", return_geoloc=FALSE, return_product=FALSE)
# 
# # Check for matches (for MODIS-AQUA platform)
# # (*will* work with the default files stored in modiscloud/extdata/2002raw/)
# check_for_matching_geolocation_files(moddir=moddir, modtxt="MYD35_L2", geoloctxt="MYD03", return_geoloc=FALSE, return_product=FALSE)
# ## End(Not run)