# Select samples automatically

Aim

To easily find:

▪Missing points.

▪Samples separated by a distance greater or smaller than a specific value. For example, to find points lying far from the normal path.

▪Samples with a surface area greater or smaller than a specific value. For example, to find all points where the detected blob is too large to be the actual subject.

▪Samples with the distance between nose-point and tail-base greater or smaller than a specific value.

To access this function

Choose Acquisition > Edit Tracks, and select the trial you want to view.

Procedure

1.On the toolbar, click the Auto Select button.

2.In the Auto Select Samples window, under Select choose the option you require. For more information, see the notes below.

3.Under Scope:

▪Select the arena you want to search. If you want to find samples in all arenas, select All arenas.

▪Select the subject you want to search. If you want to find samples in all subjects, select All subjects.

4.Click Select All.

Result: The samples matching the criterion are highlighted in the track plot. In the Samples List, the corresponding rows are highlighted in green.

5.If you chose Missing samples in step 2, click the Next>> and <<Previous buttons to move to the next or previous missing sample, respectively. There, you can decide whether to Interpolate points or leave the sample as missing.

6.If necessary, change the settings under Select and click the Select All button. When you are satisfied with the selection, click Close.

Options

Missing samples

Option Missing samples. Choose this option to select all missing samples in the track, for example to interpolate them.

Sample distance

EthoVision XT selects all the non-missing points separated from the previous or the next by a distance greater or smaller than the threshold you specify. To select samples, EthoVision XT always uses the distance between center points.

In the following example with two short tracks, the open circles represent the samples selected after using a distance threshold, indicated with the segment.

note Using > and < does not result in complementary selections. Some samples in the figure above are selected in both cases.

tip To remove outliers, for example data points resulting from detection of reflections in a water maze, select > and enter a value of distance. This value must be greater than a realistic estimate of the maximal distance that the subject could move between two consecutive samples. Note that this value also depends on the sample rate. The higher the sample rate, the shorter the distance moved by the subject between two consecutive samples. Next, do Delete points and then Interpolate points to replace the outliers.

Surface area

For this option, specify the value in the measurement unit selected in the Experiment Settings.

Nose-tailbase length

This is only available if your experiment is set to Center-point, nose-point and tail-base detection. Nose-tailbase length is the total length of the segments between nose-point and center-point, and that between center-point and tail-base point.

Restrict to samples visible in plot

Select this option if you want to select only the samples that match the Select criterion and that are currently displayed in the track plot. The other samples that match the criterion but are not displayed, are not selected.

note If you select this option and then play back the track, the samples that are not currently visualized, but that match the selection criterion under Select, are not selected. To have them selected, pause the video and click Select all once again.

To deselect samples

Do one of the following:

▪Press Esc.

▪Click anywhere on the background image that is not a point.

▪Right-click anywhere on the background image.