在sp中使用over函数：保留空间特征

Question

Hi I'm using the over function in sp package and wondering if it preserves the spatial characteristics in the results. As you know spatial characteristics is necessary to joint the data to another dataset to perform analysis.

for example: I have a control datset as spatialPointsDataFrame and slope as spatialGridDataFrame. I want to use over as follows:

> Slope.ov = over(control, Slope)  # the result is:
 'data.frame':  500 obs. of  1 variable:
 $ slope: num  NaN 0.477 0.87 1.172 0.534 ...

And then I want to add the data extracted to the control dataset. How can I make sure that the data added to control dataset is spatially in correct position?

> control$slope =Slope.ov$slope

Answer 1

over preserves the order of data. So, if you add your vector as you suggest it, data will be added in the good order to the right position.