# more robust than %in%
mz_grid <- mz_grid[(Hmisc::find.matches(mz_grid$StartBearing,
field_bearings,
tol = c_resolution/10))[["matches"]]
& (Hmisc::find.matches(mz_grid$EndBearing,
field_bearings,
tol = c_resolution/10))[["matches"]],]