knitr::opts_chunk$set( collapse = TRUE, comment = "#>", fig.path = "man/figures/README-" )
em38 translates *.n38 binary files generated by the Geonics EM38-MKII ground conductivity meter, commonly used in soil research and precision agriculture. EM38-MKII devices are supported by an official translation app called DAT38MK2, but this lacks a command-line interface and is not easy to use in a reproducible workflow.
Install from github with
library(devtools) install_github("obrl-soil/em38")
This package is in early development phase. Improving its reliability requires access to a wide variety of test datasets, so if you have an *.n38 file that fails to decode correctly, please consider sending it to me. I have been able to test decoding on around 50 sample files from two different EM38-MKII devices, but could always use more. The device and its logger have a large number of possible setting combinations, and I have not seen all of them. Additionally, a third-party GPS needs to be attached to the device and its data-logger, and GPS output data are notoriously variable by brand and model.
em38 is accompanied by a demo dataset gathered during a training exercise:
library(em38) # all-in-one wrapper function: demo_survey <- em38_from_file(path = system.file("extdata", "em38_demo.n38", package = "em38"), hdop_filter = 3) # Plot spatialised output of survey line 1 (calibrated conductivity for coil # separation 0.5m) sl1 <- demo_survey$survey_lines[[1]] plot(sl1[sl1$mode == 'Vertical', 'cond_05'], pch = 20, main = 'Conductivity, Vertical Dipole Mode, Coil Separation 0.5m')
Its surprisingly difficult to walk in a straight line across a paddock :no_mouth:
If you want to look at the intermediate data more closely,
# import binary file as raw() type matrix n38_mat <- n38_import(system.file("extdata", "em38_demo.n38", package = "em38")) # break matrix into sections according to file spec n38_chunks <- n38_chunk(n38_mat) # decode matrix chunks into useable data n38_decoded <- n38_decode(n38_chunks)
You can also create the equivalent of an *.M38 text file, for comparison.
m38_example <- n38_to_m38(n38_decoded) # write to file as e.g. # write(m38_example, paste0('m38_from_R_', Sys.Date(), '.m38'))
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