我们用来寻找相邻点之间的差异的技巧是，创建一个数据帧，它的列是给定连续数据点， 分别是先前数据点（prior）、当前数据点（current）、后继数据点（following）。
The trick we will use to find all the differences among neighboring data points is to create a data frame whose columns in a given row correspond to the prior, current, and following data point.
这个条件如第35行所示，其中，如果在一段连续的时间内对该列排序，并且以前的排序方向为升序，那么它必须切换为降序排序。
This condition is shown in line 35, where if the column is being sorted for a consecutive time and the previous direction was upward, it must be switched to downward sorting.
我们在前一节中添加了三列，这正是保持功能连续性的第一步。
We already started looking for functional continuity in the previous section by adding three columns.
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