I have a table that contains time (date) and speed values. However, the values only exist in clumps, meaning there are dates that do not have corresponding speed values. Is there any way to remove the empty dates from the x-axis and continue to the dates that have speed values?
You're using an XY (scatter) chart. That treats the dates as a continuous variable and plots their location appropriately in time. The data is plotted where the data is in time.
To eliminate the empty periods, you need a different type of chart, one that treats the X axis as "dumb". Category data is plotted one value after the other, and the dates are just identifying labels that don't have any numerical meaning.
Switch the chart type to Line chart. It may try to plot the dates as another series. Edit the series definitions to delete the dates as a series. Then select those values as labels for the series being plotted so they get used to label the axis (which may otherwise default to simple sequential numbers).
Since those are dates, they will be stored as raw day counts, and may label the axis with strange looking numbers. Format the axis numbers in the axis dialog with a date format.
Click the File tab and choose Options.
In Excel 2007, click the Office button and then click Excel options. In Excel 2003, choose Options from the Tools menu
Choose Advanced in the left pane.
In the Display options for this worksheet section, choose the appropriate sheet from the drop-down menu. Uncheck the Show a zero in cells that have zero value option