9.3.7.14 The (Plot Details) Drop Lines TabPDDialogDropLineTab
You can add drop lines to either axis in any 2D data plot type that incorporates plot symbols, and to any plane in 3D scatter and trajectory graphs.

3D Scatter, 2D/3D Ternary Graph



Direction Control for Drop Lines
For 2D graph in cartesian coordinate, Horizontal or Vertical drop lines are optional.
For 2D ternary and 3D (including 3D Ternary) graph, drop lines Parallel to X/Y/Z Axis are optional.For 3D Scatter/Trajectory graph, Drop Lines tab is available on both Original and XY/ZX/YZ Projection level: On Original level, drop lines on all three directions(parallel to X/Y/Z axis) are optional; but on XY/ZX/YZ Projection level, only two directions along the axes of current panel are optional, such as on XY Projection level, you are only allowed to turn on the drop lines parallel to X and Y axis. For 3D Ternary graph, only drop lines parallel to vertical Z axis(Zh) is available. In contrast, all three directions are allowed to add drop lines for 2D Ternary graph.
Line Style Controls
Select the Horizontal/Vertical or Parallel to X/Y/Z Axis check boxes to display horizontal or vertical lines from each data point symbol to the bottom X or left Y axis. Then select the style, width and color for the dropline with the Style, Width and Color dropdown lists.
Setting Drop Line Color
You can separately specify the color of the drop lines, using the Color Chooser just like that for the data plots.
Single Color for all drop lines
When you select Auto from the Color dropdown lists in the Single subtab, Origin uses the color selected from the Symbol Color or the Edge Color buttons on the (Plot Details) Symbol tab.
You can specify a desired color to apply it to all droplines at current direction. If you want to define and use a custom color for the drop lines, you can refer to this page.
Different Colors By Points
In the By Points subtab of Color Chooser, you can use a dataset to control the drop line color.
Just like the columns/bars in Bridge Chart, there is a special type of dataset color control for the drop lines:
 Y Value: PlusMinus: This option controls the drop line colors according to the condition that if the corresponding Y value is Positive, Negative. (Only available for Lollipop Plot)
For the drop line color, when Drop to Next Data Plot is selected, Y Value: PlusMinus will show up in the By Points subtab of color chooser:
 when Y value of next plot is bigger then this plot, then set the color of the drop line as the first color of color list
 when Y value of next plot is smaller then this plot, then set the color of the drop line as second color of color list
Like Y Value: PlusMinusTotal in bridge chart, selecting this method will also grey out the colors after the 2nd one of the color list.
Note: This special color control is also available for some other graph objects of other plot types:
 For the border and fill color of Column plot, Y Value: PlusMinus will show up in the By Points subtab of color chooser. Selecting it means:
 if Y value is bigger then custom additional line Y=, then use 1st color in the color list
 if Y value is smaller then custom additional line Y=, then use 2nd color.
 For the symbol color(including symbol edge, symbol fill color) of scatter plot and line+symbol plot, when there is vertical or horizontal drop line(one direction only), and Drop To has not been set to Next Plot, Y Value: PlusMinus will show up in the By Points subtab of color chooser. Selecting it means,
 if Y value is bigger then base line(axis or custom additional line), then use 1st color
 if Y value is smaller then base line, use 2nd color.

Drop To Controls
You can use this dropdown list to specify which line(axis line or additional line) or surface(axis panel or surface from 3D data) the current drop lines should be dropped to.
For 2D Scatter/Line graph in cartesian coordinate, four options are available under this dropdown list:
 Auto: This item is selected by default to make drop lines drop to Left X and bottom X axis.
 X/Y=Axis Begin: Make drop lines drop to the left Y Axis/bottom X axis which is at the position X/Y=Min.
 X/Y=Axis End: Make drop lines drop to the right Y Axis/top X axis which is at the position X/Y=Max.
 X/Y=Custom Additional Line:Make drop lines drop to the custom additional line at X/Y=custom value. If there is no additional line, drop lines will follow the Auto behaviors.
 Next Data Plot: Make drop lines drop to the next plot at the same X values. This item in Vertical group will be selected by default for Lollipop Plot.
For 2D Ternary graph, two target axis lines are available under this dropdown list:
 When drop lines Parallel to X Axis, you are allowed to select Y or X to specify which axis the drop lines should drop to.
 When drop lines Parallel to Y Axis, you are allowed to select X or Z to specify which axis the drop lines should drop to.
 When drop lines Parallel to Z Axis, you are allowed to select X or Y to specify which axis the drop lines should drop to.
For 3D Scatter/Trajectory graph, four options are available under this dropdown list:
 Auto:This item is selected by default to make drop lines drop to X=Min/Y=Max/Z=Min plane.
 X/Y/Z=Axis Begin Plane: Make drop lines drop to the YZ/XZ/XY panel which is at the position X/Y/Z=Min.
 X/Y/Z=Axis End Plane: Make drop lines drop to the YZ/XZ/XY panel which is at the position X/Y/Z=Max.
 Surface:Make drop lines drop to the surface which is created from 3D data. If there is no surface, drop lines will follow the Auto behaviors.
For 3D Ternary Scatter graph, only Parallel to Z Axis is available which can be used to add drop lines along vertical Z axis(Zh).
Arrow Controls
For 2D Scatter/Line graph in cartesian coordinate, you are allowed to add arrows at the end of the drop lines.
You can specify the Arrow Shape, Arrow Width and Arrow Length for the arrows. The unit of the arrow width and arrow length is points.
For the ternary and 3D graphs, Origin doesn't support to add arrows at the end of the drop lines.
Show at Specified Points Only
This control can be used to add drop lines at specific data points or at specific x values.
Here, five syntaxes are supported:
 row indices separated by spaces, such as 1 3 5 show drop lines at specified row 1,3,5
 start and end row indices with the number of skipped points, such as 2:0:5 shows 1 row and skip 5 rows, from 2nd row to the end row
 X values with space separators, but need add x= before the values, such as x=3.5 7.8 show at specified X values(3.5 and 7.8)
 row indices stored in another column which can be selected in the dropdown list, such as [Book1]sheet2!col(A) show drop lines at specified rows, with row indices from this selected column
 X values stored in another column which can be selected in the dropdown list, but need add x= before the range, such as x=[Book1]sheet2!col(A) show at specified X values, with X values from this selected column
Please note, when you are adding the drop lines by specifying the X values, if the specified x values are not dropped on the data points, the interpolation will be performed to locate the specified X values at the connect lines between the nearest data points. And, only when the Line Connect had been set to Straight, the drop lines specified by X values will work. See an example as below:
Data Points Display Control
Specify whether and how to skip data points when show the drop lines.
No Skipping Points
All data points will have their own droplines, without any skipping point. This is the default seletction for this control group.
Skip Points by Increment
Select the Skip Points by Increment from the dropdown list to display a specified frequency of data points, then type the frequency in the associated text box. This setting also effects the display of the data plot drop lines, symbols, error bars, and data labels.
If n is entered in the Skip Points text box, then only the first out of every n data points will be displayed; the remaining n1 data points will be skipped. But the last data point will always show. If you want to hide the last point, set @SMEP = 0. n must be an integer value greater than or equal to 2. If n = 0 or 1, no point is skipped.
If the plot contains a line plot, then you can use the No Line Break for Skipped Point(s) check box to specify whether to break the line if points are skipped. If this is selected, the line will still be continuous even though the data points are skipped.
Smart Skip
Select one of the Smart Skip options, to skip the data points with a smart caculation based on the data density abd curve shape.
Smart Skip(Total Points Kept)
Smart skip the data points by specifying the total data points kept after skipping.
Smart Skip(% of Points Skipped)
Smart skip the data points by specifying how many data points will be skiped with a percentage of all data points.
Smart Skip Method
Based on the different curve shape and data density, there are four methods selectable to skip the data points:
 Largest Triangle: Find a point near the midpoint, this point(1) should be the largest triangle in area with the start point and end point. Then, point 1 will divide the whole curve to two segments, each segment will do the same calculation as that of finding point 1 to find point 2 and point 3. Compare the triangle area of point 2 and point 3 in their segment, keep the one which has the larger area.
Follow this algorithm to search step by step, each time only the point with the largest triangular area (between the current largerarea triangle and the higherlevel smaller triangle) is kept until the set number of points is reached.
 Ythreshold: According to the number of points you want to find, calculate a threshold on Y axis distance using the iterative method; Then, keep the points under the threshold.
 Data Distance Threshold: According to the number of points you want to find, calculate a threshold with larger triangle area using the iterative method; Then, keep the points under the threshold.
 Douglas Peucker Hull: Use the Douglas–Peucker algorithm to decimate a curve composed of line segments to a similar curve with fewer points.
 Largest Triangle for Segments: Divide the curve into several segments, and then follow the largest triangle algorithm to find the points. Each segment will find some number of data points.
