PHPExcel X-Axis labels missing on scatter plot - time-series

Question

I'm attempting to create some scatter plot charts with multiple series based on a time scale and I'm having a few issues. Note that the timestamps for each series may be different hence the need to use a scatter plot.
I'll backtrack in reverse order but consider the following code:
define('EOL',(PHP_SAPI == 'cli') ? PHP_EOL : '<br />');
require_once __DIR__.'/phpexcel/Classes/PHPExcel.php';
require_once __DIR__.'/phpexcel/Classes/PHPExcel/Cell/AdvancedValueBinder.php';
PHPExcel_Cell::setValueBinder( new PHPExcel_Cell_AdvancedValueBinder() );
$objPHPExcel = new PHPExcel();
$objWorksheet = $objPHPExcel->getActiveSheet();
$objWorksheet->fromArray(
array(
array('','SERIES_1','SERIES_2'),
array('2014-05-01 00:00:03',12574,''),
array('2014-05-01 04:10:01',7347,''),
array('2014-05-02 09:20:01',4175,''),
array('2014-05-03 21:30:03',1045,''),
array('2014-05-01 07:05:03','',8544),
array('2014-05-02 12:15:01','',1324),
array('2014-05-02 16:25:01','',6729),
array('2014-05-03 15:35:03','',9420),
)
);
$objWorksheet->getStyle('A2:A9')
->getNumberFormat()
->setFormatCode('yyyy-mm-dd hh:mm:ss');
// Set the Labels for each data series we want to plot
// Datatype
// Cell reference for data
// Format Code
// Number of datapoints in series
// Data values
// Data Marker
$dataseriesLabels = array(
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$B$1', NULL, 1),
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$C$1', NULL, 1),
);
// Set the X-Axis Labels
$xAxisTickValues = array(
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$A$2:$A$9', NULL, 8),
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$A$2:$A$9', NULL, 8),
);
// Set the Data values for each data series we want to plot
// Datatype
// Cell reference for data
// Format Code
// Number of datapoints in series
// Data values
// Data Marker
$dataSeriesValues = array(
new PHPExcel_Chart_DataSeriesValues('Number', 'Worksheet!$B$2:$B$9', NULL, 8),
new PHPExcel_Chart_DataSeriesValues('Number', 'Worksheet!$C$2:$C$9', NULL, 8)
);
// Build the dataseries
$series = new PHPExcel_Chart_DataSeries(
PHPExcel_Chart_DataSeries::TYPE_SCATTERCHART, // plotType
NULL, // plotGrouping (Scatter charts don't have any grouping)
range(0, count($dataSeriesValues)-1), // plotOrder
$dataseriesLabels, // plotLabel
$xAxisTickValues, // plotCategory
$dataSeriesValues, // plotValues
NULL, // smooth line
PHPExcel_Chart_DataSeries::STYLE_LINEMARKER // plotStyle
);
// Set the series in the plot area
$plotarea = new PHPExcel_Chart_PlotArea(NULL, array($series));
// Set the chart legend
$legend = new PHPExcel_Chart_Legend(PHPExcel_Chart_Legend::POSITION_RIGHT, NULL, false);
$title = new PHPExcel_Chart_Title('CHART_TITLE');
$yAxisLabel = new PHPExcel_Chart_Title('Y_AXIS_TITLE');
$xAxisLabel = new PHPExcel_Chart_Title('X_AXIS_TITLE');
// Create the chart
$chart = new PHPExcel_Chart(
'chart1', // name
$title, // title
$legend, // legend
$plotarea, // plotArea
true, // plotVisibleOnly
0, // displayBlanksAs
$xAxisLabel, // xAxisLabel
$yAxisLabel // yAxisLabel
);
// Set the position where the chart should appear in the worksheet
$chart->setTopLeftPosition('E3');
$chart->setBottomRightPosition('N18');
// Add the chart to the worksheet
$objWorksheet->addChart($chart);
// Save Excel 2007 file
echo date('H:i:s') , " Write to Excel2007 format" , EOL;
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->setIncludeCharts(TRUE);
$objWriter->save(str_replace('.php', '.xlsx', __FILE__));
echo date('H:i:s') , " File written to " , str_replace('.php', '.xlsx', pathinfo(__FILE__, PATHINFO_BASENAME)) , EOL;
The real data will ultimately come from a database but right now I'm just trying to make things work during testing. This appears to work and while I need to do some manual formatting at the moment (remove markers, change line thickness, position axis on tick marks, change number format to yyyy-mm-dd) the graph appears to generate properly.
However if I only use one data series the graph generates properly but the x axis labels are missing. The tick marks are in the right place, only the labels are missing. As noted in the following code all I've done is comment out the second set of data.
define('EOL',(PHP_SAPI == 'cli') ? PHP_EOL : '<br />');
require_once __DIR__.'/phpexcel/Classes/PHPExcel.php';
require_once __DIR__.'/phpexcel/Classes/PHPExcel/Cell/AdvancedValueBinder.php';
PHPExcel_Cell::setValueBinder( new PHPExcel_Cell_AdvancedValueBinder() );
$objPHPExcel = new PHPExcel();
$objWorksheet = $objPHPExcel->getActiveSheet();
$objWorksheet->fromArray(
array(
array('','SERIES_1','SERIES_2'),
array('2014-05-01 00:00:03',12574,''),
array('2014-05-01 04:10:01',7347,''),
array('2014-05-02 09:20:01',4175,''),
array('2014-05-03 21:30:03',1045,''),
array('2014-05-01 07:05:03','',8544),
array('2014-05-02 12:15:01','',1324),
array('2014-05-02 16:25:01','',6729),
array('2014-05-03 15:35:03','',9420),
)
);
$objWorksheet->getStyle('A2:A9')
->getNumberFormat()
->setFormatCode('yyyy-mm-dd hh:mm:ss');
// Set the Labels for each data series we want to plot
// Datatype
// Cell reference for data
// Format Code
// Number of datapoints in series
// Data values
// Data Marker
$dataseriesLabels = array(
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$B$1', NULL, 1),
// new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$C$1' NULL, 1),
);
// Set the X-Axis Labels
$xAxisTickValues = array(
new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$A$2:$A$9', NULL, 8),
// new PHPExcel_Chart_DataSeriesValues('String', 'Worksheet!$A$2:$A$9', NULL, 8),
);
// Set the Data values for each data series we want to plot
// Datatype
// Cell reference for data
// Format Code
// Number of datapoints in series
// Data values
// Data Marker
$dataSeriesValues = array(
new PHPExcel_Chart_DataSeriesValues('Number', 'Worksheet!$B$2:$B$9', NULL, 8),
// new PHPExcel_Chart_DataSeriesValues('Number', 'Worksheet!$C$2:$C$9', NULL, 8)
);
// Build the dataseries
$series = new PHPExcel_Chart_DataSeries(
PHPExcel_Chart_DataSeries::TYPE_SCATTERCHART, // plotType
NULL, // plotGrouping (Scatter charts don't have any grouping)
range(0, count($dataSeriesValues)-1), // plotOrder
$dataseriesLabels, // plotLabel
$xAxisTickValues, // plotCategory
$dataSeriesValues, // plotValues
NULL, // smooth line
PHPExcel_Chart_DataSeries::STYLE_LINEMARKER // plotStyle
);
// Set the series in the plot area
$plotarea = new PHPExcel_Chart_PlotArea(NULL, array($series));
// Set the chart legend
$legend = new PHPExcel_Chart_Legend(PHPExcel_Chart_Legend::POSITION_RIGHT, NULL, false);
$title = new PHPExcel_Chart_Title('CHART_TITLE');
$yAxisLabel = new PHPExcel_Chart_Title('Y_AXIS_TITLE');
$xAxisLabel = new PHPExcel_Chart_Title('X_AXIS_TITLE');
// Create the chart
$chart = new PHPExcel_Chart(
'chart1', // name
$title, // title
$legend, // legend
$plotarea, // plotArea
true, // plotVisibleOnly
0, // displayBlanksAs
$xAxisLabel, // xAxisLabel
$yAxisLabel // yAxisLabel
);
// Set the position where the chart should appear in the worksheet
$chart->setTopLeftPosition('E3');
$chart->setBottomRightPosition('N18');
// Add the chart to the worksheet
$objWorksheet->addChart($chart);
// Save Excel 2007 file
echo date('H:i:s') , " Write to Excel2007 format" , EOL;
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->setIncludeCharts(TRUE);
$objWriter->save(str_replace('.php', '.xlsx', __FILE__));
echo date('H:i:s') , " File written to " , str_replace('.php', '.xlsx', pathinfo(__FILE__, PATHINFO_BASENAME)) , EOL;
As mentioned above the tick marks are in the right place, only the labels are missing.
Any ideas on why the x axis labels don't show up? Also, if I create a scatter plot in Excel manually (Insert >> Chart >> Scatter) I get a time scale chart with x axis options to select minimum, maximum, major unit, and minor unit whereas the graphs from PHPExcel appear to be a category/value type since you can only select interval between tick marks and interval unit. Is there any way to change this?
Edit: Forgot to mention that I've tried using both the 1.8.0 release of PHPExcel as well as the latest develop branch on git.