Select range values

[joemParticipant]

Hello,

I have 2 columns of values to create a stress-strain curve.

I would like to select a certain number of values to create a linear fit (let’s say in the first 50 values) to find the angular coefficient (Modulus of Elasticity).

Is it possible without creating 2 new columns with just the values I need?

[dgteamModerator]

Yes – there are a couple of ways to limit the data included.  Here is what I would recommend for the specific example of wanting the first 50 rows.

Say you have a Fit command and a Points command drawing the data …

If you expand the fit you can see how many points are included.  There is also a place to add a filter, or ‘Use as Mask’.  By default, it is set to ‘Fit all’.

Masks allow you to set up a logical statement for including or excluding data based on some criteria.

Create a Mask in the Fit command

Step 1:  Set the Use as Mask menu to the ‘#’ row counter.

Step 2: Select the logical criteria,  ‘≤’

Step 3:  Select the number to compare to, ’50’

When you are done, note the change in the same size.

The problem with creating the mask in the Fit command is that now the Points command would show all the data, while the Fit is only a portion.

You can add the same criteria to the Points command, but another way is to use a group.

Create the mask at the group level

Step 1: Select both commands (Points & Fit) (hold down the shift-key and click each)

Step 2:  Click the Group icon short-cut on the right side of the tool bar.  This places both commands in a common group.

Step 3:  Create a shared mask at the group level …

Now the points that are plotted have the same filter as the fit.

Does this make sense?

[Author]

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