Calculate and plot mean values of pairs of data points

Question

I have a list of data points where there can be multiple y values for a given x value, e.g., {{0, 4}, {1, 2}, {1, 3}, {2, 3}}. I would like to

• Take the mean of the y values for each x value. Get a list of unique value pairs.
• Then I would like to plot the unique set of x,y values.
• Then smooth the curve
• Then fit the curve with a function.

Is there a simple way to do this? Thanks!

Answer 1

One possibility is to use GroupBy:

assoc = GroupBy[{{0,4},{1,2},{1,3},{2,3}},First->Last,Mean]

<|0 -> 4, 1 -> 5/2, 2 -> 3|>

You can actually plot this association directly:

ListPlot[assoc]

But you might want to convert this to list of pairs:

KeyValueMap[List] @ assoc

{{0, 4}, {1, 5/2}, {2, 3}}