checkSimValueInSer: Check for similar values in series
Description
This function checks all values of 'x' for similar neighbour values within (relative) range of 'ppm' (ie parts per milion as measure of distance).
By default values will be sorted internally, so if a given value of x has anywhere in x another value close enough, this will be detected.
However, if sortX=FALSE only the values next to left and right will be considered.
Return logical vector : FALSE for each entry of 'x' if value inside of ppm range to neighbour (of sorted values)