Pos/Neg Waterfall Chart

This example demonstrates a waterfall chart with positive and negative data shown in different colors.

This chart is created as a box-whisker layer using XYChart.addBoxWhiskerLayer. Only the "box" part of the box-whisker layer is used.

The top-edges of the boxes are obtained by accumulating the raw data using the ArrayMath utility. The bottom-edges of the boxes are simply the top-edges of previous boxes, with the exception of the last "total" box which always starts at 0.

The color for each box is set using BoxWhiskerLayer.setBoxColor, in which the color depends on whether the top-edge is above or below the bottom-edge (that is, whether the data is positive or negative).

[File: phpdemo/posnegwaterfall.php]

<?php
require_once("../lib/phpchartdir.php");

# 4 data points to represent the cash flow for the Q1 - Q4
$data = array(230, -140, 220, 330);

# We want to plot a waterfall chart showing the 4 quarters as well as the total
$labels = array("1st Quarter", "2nd Quarter", "3rd Quarter", "4th Quarter", "Total");

# The top side of the bars in a waterfall chart is the accumulated data. We use the
# ChartDirector ArrayMath utility to accumulate the data. The "total" is handled by
# inserting a zero point at the end before accumulation (after accumulation it will
# become the total).
$tmpArrayMath1 = new ArrayMath($data);
$tmpArrayMath1->insert2(0, 1, count($data));
$tmpArrayMath1->acc();
$boxTop = $tmpArrayMath1->result();

# The botom side of the bars is just the top side of the previous bar. So we shifted
# the top side data to obtain the bottom side data.
$tmpArrayMath1 = new ArrayMath($boxTop);
$tmpArrayMath1->shift(1, 0);
$boxBottom = $tmpArrayMath1->result();

# The last point (total) is different. Its bottom side is always 0.
$boxBottom[count($boxBottom) - 1] = 0;

# In this example, we want to use different colors depending on the data is positive
# or negative.
$posColor = 0x00ff00;
$negColor = 0xff0000;

# Create a XYChart object of size 500 x 280 pixels. Set background color to light
# blue (ccccff), with 1 pixel 3D border effect.
$c = new XYChart(500, 300, 0xccccff, 0x000000, 1);

# Add a title to the chart using 13 points Arial Bold Itatic font, with white
# (ffffff) text on a deep blue (0x80) background
$textBoxObj = $c->addTitle("Corporate Cash Flow - Year 2004", "arialbi.ttf", 13,
    0xffffff);
$textBoxObj->setBackground(0x000080);

# Set the plotarea at (55, 50) and of size 430 x 215 pixels. Use alternative
# white/grey background.
$c->setPlotArea(55, 50, 430, 215, 0xffffff, 0xeeeeee);

# Add a legend box at (55, 25) using 8 pts Arial Bold font with horizontal layout,
# with transparent background and border color.
$b = $c->addLegend(55, 25, false, "arialbd.ttf", 8);
$b->setBackground(Transparent, Transparent);

# Add keys to show the colors for positive and negative cash flows
$b->addKey("Positive Cash Flow", $posColor);
$b->addKey("Negative Cash Flow", $negColor);

# Set the labels on the x axis using Arial Bold font
$labelsObj = $c->xAxis->setLabels($labels);
$labelsObj->setFontStyle("arialbd.ttf");

# Set the x-axis ticks and grid lines to be between the bars
$c->xAxis->setTickOffset(0.5);

# Use Arial Bold as the y axis label font
$c->yAxis->setLabelStyle("arialbd.ttf");

# Add a title to the y axis
$c->yAxis->setTitle("USD (in millions)");

# Add a box-whisker layer to represent the waterfall bars
$layer = $c->addBoxWhiskerLayer($boxTop, $boxBottom);

# Color the bars depending on whether it is positive or negative
for($i = 0; $i < count($boxTop); ++$i) {
    if ($boxTop[$i] >= $boxBottom[$i]) {
        $layer->setBoxColor($i, $posColor);
    } else {
        $layer->setBoxColor($i, $negColor);
    }
}

# Put data labels on the bars to show the cash flow using Arial Bold font
$layer->setDataLabelFormat("{={top}-{bottom}}M");
$textBoxObj = $layer->setDataLabelStyle("arialbd.ttf");
$textBoxObj->setAlignment(Center);

# Output the chart
header("Content-type: image/png");
print($c->makeChart2(PNG));
?>