使用R找到最近的X，Y坐标

I'm just starting to learn R but would like project done sooner rather than later. It's rather simple: I have an X column and a Y column consisting of X coordinates and Y coordinates. (Working in the NAD27 coordinate system). Going from the first coordinate, I'd like to find the nearest point within the data set and then move onto the next coordinate and find it's nearest point within the same data set. Ideally, it would go through each point and determine the closest point. I'm just starting to learn R but would like pro