The Line chart view draws a project table as curves. One column of the table gives the horizontal values and every other column that contains only numbers becomes a curve of its own, so a set of related measurements can be compared in a single picture.

To create a Line chart view go to the Views bar, navigate to Graphs and click on Line chart. The new view appears in the View manager of the active workspace and stays empty if no project table is available.

Choosing the data

The data of the chart is selected on the Statistical analysis bar: choose Line chart in the Graph type list of the General group, then fill in the Line chart group.

• Data source - Tables is the only source of this graph. The tables that are offered are the ones kept in the Tables folder of the Statistics category, which is described in Statistical analysis.
• Table - the table that is drawn.
• X column - the column that gives the horizontal values. The first column of the table is used until another one is chosen. A numeric X column sets horizontal positions; a column containing text uses its cell values as categories in table row order.
• From row and To row - restrict the chart to a window of table rows. The values are row numbers, counted from 1 for the first row of the table, and both ends are included. Leave both at 0 to draw the whole table. A number outside the table is trimmed to it and a window that is entered the wrong way round is turned over, so the chart is never left empty. While a window is in use, the title of the horizontal axis reports the rows that are drawn.

Tables created or imported into the Tables folder under Statistics appear in the Table list while the Line chart is open. Choose a table to make its columns available in X column. Click Update graphs to refresh the list manually.

Every column apart from the X column is drawn as a curve, provided that all of its values are numbers; a column that holds any text is not offered as a curve at all. An empty cell is a gap and not a zero, so a curve breaks at a missing value and continues after it. Rows are taken in the order in which they stand in the table and are not sorted, so a column whose values rise and fall draws a line that doubles back.

An open Line chart follows the table it was built from: values that are changed in the table editor are redrawn, a numeric column that is added appears as a new curve, and a column that is renamed keeps its curve. If the selected table is renamed, its new name appears in the Table list and the chart keeps using it. If it is deleted, the view stays open and reports it.

Curves

Each drawn column is listed as an object item under Curves in the Object(s) tab of the Visual Settings panel. Clear the check box of a curve to take it off the chart and out of the legend, and select the check box again to bring it back with its style. Select a curve to edit it in the Object item properties section, where Transparency level, Point type, Point color, Point size, Line color, Line transparency, Line size, Connection type and Line type apply to that curve alone. Connection type and Point size together decide whether the curve is drawn as a line, as markers only, or as a line with markers.

Visibility and style are kept per column name and not per column position, so inserting, moving or renaming a column in the table leaves every curve with its own settings.

At most 12 curves are drawn automatically. When the table holds more numeric columns, the remaining curves are listed in Object items without a tick, and the title of the vertical axis reports how many of the curves are shown.

Axes and legend

The horizontal axis takes the name of the X column. The vertical axis takes the name of the curve when exactly one curve is shown and Value when several are shown, and the legend then tells the curves apart, each with its own line and marker style. The scale type of each axis is set in the View tab of the Visual Settings panel. A new Line chart has Auto precision selected by default, so small decimal values remain readable in the vertical-axis labels. To use a fixed number of decimal places, clear Auto precision in the View tab and enter a whole number in Vertical scale precision (for example, 2 for hundredths). A value that is zero or negative has no place on a logarithmic scale, so such values are left out of the curve and their number is added to the title of that axis.

When the chart cannot be drawn, the reason takes the place of the horizontal axis title - for example when no table has been selected yet, when the selected table is empty or holds a single column, or when no other numeric column is left to draw.

Saving and exporting

Right-click the plot to open the context menu of the view:

• Save Line chart to Data Manager... - asks for a Name and stores the chart in the Line chart folder of the Statistics category of the Data manager. Opening it again restores the table, the X column, the row window and the visibility and style of every curve. A name that is already used in that folder is refused.
• Export Line chart picture to PNG... - writes the chart as it currently looks to a PNG file.
• Export Line chart data to CSV... - writes the drawn values to a CSV file: the X column followed by every curve that is shown, over the rows that are currently in use.