chart_label sets the attributes of the labels that appear over the graphs. Chart labels are the red labels here:
The text of the chart labels is generated by default from chart_data. To override the default text and create custom labels, use chart_data label
prefix: The characters to add before numbers (example: $10). The default is nothing.
suffix: The characters to add after numbers (example: 10%). The default is nothing.
decimals: The number of decimal places to the right of the decimal point (example: 10.45). The default is zero (no decimals).
decimal_char: The character to use at the left of a decimal fraction (example: 1.5). The default is '.' (dot or full stop).
separator: The character to place between every group of thousands (example: 1,00,000). The default is nothing.
position: The position where to place the labels. Each chart type has a different set of position values (see Label Position below).
hide_zero: This determines whether to hide value labels equal to zero. The default is false (shows zero labels).
as_percentage: This is relevant in pie charts only. It determines whether to display the values as raw data, or as percentages of the whole pie. The default is false.
font: The font used for the chart labels (see Fonts). The default is Arial.
bold: A boolean that indicates whether the font is bold or not. The default is true.
size: The font's size. The default font size is calculated based on the background size.
color: The font's color. This is a string holding triple hexadecimal values representing the red, green, and blue components of a color. The default is "000000" (black).
alpha: This affects the labels' transparency only when the embedded font is used (see Fonts). Valid values are 0 (fully transparent) to 100 (fully opaque). The default is 100.
shadow: The ID of a shadow filter to apply to chart labels. This is omitted by default (no shadow).
bevel: The ID of a bevel filter to apply to chart labels. This is omitted by default (no bevel).
glow: The ID of a glow filter to apply to chart labels. This is omitted by default (no glow).
blur: The ID of a blur filter to apply to chart labels. This is omitted by default (no blur).
Label Position
Each chart type has different values for the 'position' key. The valid values are:
Line chart: center, above, below, left, right, hide Column chart: top, bottom, middle, middle-up, middle-down, outside, hide Stacked Column chart: top, bottom, middle, middle-up, middle-down, hide Floating Column chart: inside, outside, hide 3D Column chart: over, middle, hide Image Column chart: top, bottom, middle, middle-up, middle-down, outside, hide Stacked 3D Column chart: middle, hide Parallel 3D Column chart: over, middle, hide Pie charts: inside, outside, circular, hide 3D Pie charts: inside, outside, circular, hide Image Pie charts: inside, outside, circular, hide Donut charts: inside, hide Bar chart: left, center, right, outside, hide Stacked Bar chart: left, center, right, hide Floating Bar chart: inside, outside, hide Area chart: center, above, below, left, right, hide Stacked Area chart: center, above, below, left, right, hide 3D Area chart: above, hide 3D Stacked Area chart: above, hide Candlestick chart: Candlestick chart has no chart labels. Use tooltip instead. Scatter chart: center, above, below, left, right, hide Polar chart: center, above, below, left, right, hide Bubble chart: center, hide Mixed chart: If one position key belonging to the above chart types isn't sufficient to show all the labels on a mixed chart, add more keys separated by underscores. For example, a column and line mixed chart can have the position key "top_above".
To display labels at the cursor position, see tooltip.
The default value for the pie chart is inside. All the other charts default to hide.