improve function documentation

- add function documentation for signalNoiseRation
- improve load_and_tidy_up_GPS function documentation
- update changelog

inst/NEWS.Rd

@@ -1,6 +1,12 @@
 \name{NEWS}
 \title{News for Package \pkg{GGIRread}}
 \newcommand{\cpkg}{\href{http://CRAN.R-project.org/package=#1}{\pkg{#1}}}
+\section{Changes in version 0.0.5 (release date:05-03-2024)}{
+    \itemize{
+      \item More formats for GPS satillitate info now supported, see #12
+      \item Add documentation for GPS csv file format
+    }
+}
 \section{Changes in version 0.0.4 (release date:28-09-2023)}{
     \itemize{
       \item Handle absence of activity bouts

man/hbGPS.Rd

@@ -17,7 +17,7 @@
 }
 \arguments{
   \item{gps_file}{
-    Path to GPS file in .csv format
+    Path to GPS file in .csv format. For details on format see \link{load_and_tidy_up_GPS}
   }
   \item{GGIRpath}{
     Path to GGIR time series ouput folder (ms5.outraw)

man/load_and_tidy_up_GPS.Rd

@@ -12,7 +12,7 @@
 }
 \arguments{
   \item{gps_file}{
-    Path to GPS file in .csv format
+    Path to GPS file in .csv format, see details for format.
   }
   \item{idloc}{
     Number to indicato id location in file name (same as GGIR)
@@ -24,6 +24,16 @@
     See \link{hbGPS}
   }
 }
+\details{
+  The code ignores letter case when reading column names. The GPS csv file is 
+  expected to have the following column names: latitude or lat; longitude or lon;
+  nat(used/view) or nat (used/view) where the value format can be
+  3 (2), 3(2), 3/2, 3 / 2; a column with at least the character string "sat info " 
+  where the valueformat can be "(1-1-1-10);(1-1-1-10)" or "#1-1-1-10;#1-1-1-10" where
+  the number values per substring does not have to be 4 but the last value is always assumed
+  to reflect SNR; a column name height(m); a column named speed(km/h); 
+  a column local data or just date, and; a column local time or just time.
+}
 \value{
   List with a data.frame df that holds the GPS time series
   and ID a scalar to hold the ID of the participant.

man/signalNoiseRatio.Rd

@@ -0,0 +1,21 @@
+\name{signalNoiseRatio}
+\alias{signalNoiseRatio}
+\title{
+  Derive signal to noise ratios
+}
+\description{
+  Derive signal to noise ratios from GPS data
+}
+\usage{
+  signalNoiseRatio(df)
+}
+\arguments{
+  \item{df}{
+    Data,frane as genated by \link{load_and_tidy_up_GPS}
+  }
+}
+\value{
+  List with a data.frame df that holds the GPS time series,
+  Boolean snr_available and snr_ratio_available to indicate whether
+  the two signal to noise ratios are available.
+}