I have a dataset that I am plotting but there are clear trends occurring within the data that I would like to remove. I have attached a figure of a plot of some of the data. The y variable is supposed to increase exponentially as x increases, but at some points (between 9 and 14 x values), there is a control placed on the y output, causing it to hover around certain values as x increases.
Does anyone know how I may be able to identify these regions where the data has a clear linear trend between certain x values? I would usually think to have a polynominal equation fitted on the data and then index any data points that lie outside the error margins of this fit. However, I can only fit that equation by removing these irregular trends first, so a bit of an issue there.
These linear trend regions do not usually happen in chronological sequence. For instance, there may be a few period in time where the y-output is limited along x, creating a seemingly continuous trend. Thus I cannot use the 'diff' function for instance to easily identify periods when y-output varies by a specified amount. Hope that makes sense.
Feel free to ask me if I need to explain more.