#### Introduction

We have a customer who wants to detect the position of jumps in his signal data and put that information into a worksheet for further use. While it can be done in older versions of Origin, **Origin 2021b** makes it easy to do- it only requires one function call in a Set Column Values formula.

The function is `idx()`

and it is new in Origin 2021b. It accepts a "column conditional expression" and returns a `dataset`

(vector) of integers containing the one-based row index of all the records that meet the condition.

Here are some examples of column formulas using the function:

idx(B==100) // Returns indices of values in B that equal 100 idx(B>=20 && B<=50) // Returns indices of values in B are between 20 and 50 idx(left(A,5)$ == "Chris") // Returns indices of values in A where first 5 letters are "Chris" idx(diff(B)>1) // Returns indices in B where the difference between one value and the next value is greater than 1

As you can see, the function is able to accept other functions as part of the "column condition expression".

So, now let's apply the `idx()`

function to a few example signals to highlight how Origin 2021b can make it easy for the customer to detect jump positions .

#### Getting Started

When I refer to a "jump", I mean something like what is displayed in the graph to the right. At some distinct point, the data literally jumps- it makes a clear, abrupt transition. In the case of this graph, there are four jumps and each has a jump start and jump end.

These transitions are, of course, detectable in Origin. We can use the `diff()`

function (documentation) to compare a value in a column (e.g. `0`

) to the next value (e.g. `5`

) and then return the difference. In the case on the right, `diff()`

would calculate many zeros, four `5`

's (jump starts), and four `-5`

's (jump ends).

With that knowledge, we can leverage `diff()`

and `idx()`

in combination in a Column Values formula like: `idx(diff(B)>1)`

. The formula says *"Get the row indices from column B where the difference between one record and the next is greater than 1".*

In all the coming examples, the worksheet arrangement is the same for all *(see below)*. Observe not only are there X & Y columns, there is a column jump index formula result. There are two more columns- one containing the X values for the jump indices and one containing the Y values. Only the Columns Values formula will change a little. *Note: On the graph, the jumps are denoted by a red droplines.*

#### Examples

*Note: All the examples below are available in the downloadable companion project file.*

#### Bonus Example

There is another variation on this. What if you simply want the *last* jump in a series? Again we'll use `idx(diff(B)>1)`

but with a small modification. To get *the* last item returned by the code, change it to this: `idx(diff(B)>1)[0]`

. In this case, `[0]`

mean the last value in a dataset. So that code says *"Get the last row index from column B where the difference between one record and the next is greater than 1".*

Such code can be used in a cell formula as illustrated below.

#### Conclusion

Thanks for taking the time to read this post. I hope it provided valuable information.