Graphics.Google.Chart

This module is for generating web-based charts using Google's Chart API: http://code.google.com/apis/chart/. Its output is URLs that will resolve to a PNG image of the resulting chart.

Most of the functions in this module, with names like setFoo, take a Chart as an argument and produce a new Chart with the specified attribute added. These calls are designed to be chained together. See the example below.

Charts are represented as a hierarchy of type classes so that parameters that only affect a specific chart type are only available to that chart type.

putStrLn "URL for your chart:"
putStrLn $ chartURL $
  setSize 400 257 $
  setTitle "My Chart" $
  setData (encodeDataSimple [[1..20]]) $
  setLegend ["1 to 20"] $
  newLineChart

This produces: http://chart.apis.google.com/chart?chs=400x257&chtt=My+Chart&chd=s%3aBCDEFGHIJKLMNOPQRSTU&chdl=1+to+20&cht=lc

Remaining features to implement:

• lxy line charts
• chbh bar charts
• scatter plots
• background/fill colors
• all style attributes

Chart basics

These functions and types are shared by all chart types.

class Chart c

The type class underneath all Charts.

Instances

Chart VennDiagram

Chart BarChart

Chart PieChart

Chart LineChart

chartURL :: Chart c => c -> String

Construct the URL used to show the chart.

setSize :: Chart c => Int -> Int -> c -> c

Set the width and height, in pixels, of the resulting image.

setTitle :: Chart c => String -> c -> c

Set the title of the chart.

setTitleOpts

Arguments

:: Chart c

=> String

Color of the text.

-> Int

Size of the text.

-> c

-> c

Set options for the display of the title of the chart.

setData :: Chart c => ChartData -> c -> c

Set the data displayed by the chart.

Chart data

There are multiple options for encoding chart data. See http://code.google.com/apis/chart/#chart_data for more details on the tradeoffs of the different encoding options.

data ChartData

All the encoding methods produce ChartData, which is usable by setData.

Instances

Show ChartData

encodeDataSimple :: [[Int]] -> ChartData

Encode data using the "simple" encoding, which maps each input value to a single letter in the URL. This produces minimal URLs but doesn't have as lot of resolution. Input values must be in the range 0 <= x <= 61. Values outside the valid input range will be considered missing data.

encodeDataText :: RealFrac a => [[a]] -> ChartData

Encode data using the "text" encoding, which maps each input value to its string representation (e.g. "3.4") in the URL. This has more resolution than simple encoding but produces larger URLs. Input values must be in the range 0 <= x <= 100. Values outside the valid input range will be considered missing data. Values with more than one decimal place of resolution will be rounded.

encodeDataExtended :: [[Int]] -> ChartData

Encode data using the "extended" encoding, which maps each input value to a two-character pair in base 64. This has more resolution than text encoding and is more compact. Input values must be in the range 0 <= x <= 4095. Values outside the valid input range will be considered missing data.

setDataColors :: Chart c => [String] -> c -> c

Set data set colors. The nth color specified here colors the nth data set in the ChartData passed to setData. See http://code.google.com/apis/chart/#line_bar_pie_colors for more information.

Chart features

Legends

class Chart c => LegendChart c

LegendChart represents charts that can display legends with setLegend.

Instances

LegendChart VennDiagram

LegendChart BarChart

LegendChart LineChart

setLegend :: LegendChart c => [String] -> c -> c

Set the legend for the corresponding data sets. The colors are taken from the data set colors.

Axis labels

The order of elements in the lists passed to these functions matter: If the first AxisType passed to setAxisTypes is AxisBottom, then the first set of labels passed to setAxisLabels refers to that bottom axis.

class Chart c => AxisLabelChart c

AxisLabelChart represents charts that can display axis labels.

Instances

AxisLabelChart BarChart

AxisLabelChart LineChart

setAxisTypes :: AxisLabelChart c => [AxisType] -> c -> c

Set which axes to display. Repeating an AxisType produces multiple sets of labels on that axis.

data AxisType

Where to display an axis.

Constructors

AxisBottom

AxisTop

AxisLeft

AxisRight

setAxisLabels :: AxisLabelChart c => [[String]] -> c -> c

Set axis labels. The nth list of strings in the argument sets the labels for the nth axis specified with setAxisTypes. An empty list of strings skips labelling the corresponding axis.

setAxisLabelPositions :: AxisLabelChart c => [[Int]] -> c -> c

Set axis label positions. The nth list of Ints in the argument sets the positions for the nth axis specified with setAxisTypes. An empty list skips setting position for the corresponding axis.

setAxisRanges :: AxisLabelChart c => [(Int, Int)] -> c -> c

Set axis ranges. The nth pair of Ints in the argument sets the range for the nth axis specified with setAxisTypes.

data AxisAlignment

Text alignment for labels on an axis.

Constructors

AlignLeft

AlignCenter

AlignRight

setAxisStyles :: AxisLabelChart c => [(String, Int, AxisAlignment)] -> c -> c

Set axis styles. The nth element in the argument sets the style for the nth axis specified with setAxisTypes. Each style is a tuple of (color, font size, text alignment).

Specific chart types

Line charts

data LineChart

Instances

AxisLabelChart LineChart

LegendChart LineChart

Chart LineChart

newLineChart :: LineChart

Pie charts

data PieChart

Instances

Chart PieChart

newPieChart :: PieStyle -> PieChart

data PieStyle

Constructors

Pie2D

Pie3D

setLabels :: [String] -> PieChart -> PieChart

Set labels for the different data points on the chart. Specify missing values by passing an empty string.

Bar charts

data BarChart

Instances

AxisLabelChart BarChart

LegendChart BarChart

Chart BarChart

newBarChart :: Orientation -> BarStyle -> BarChart

data Orientation

Constructors

Horizontal

Vertical

data BarStyle

Constructors

Stacked

Grouped

Venn diagrams

data VennDiagram

Venn diagram data is specified in a particular format. There should be exactly seven data values, which represent, in order: circle A size, circle B size, circle C size, A/B overlap, A/C overlap, B/C overlap, A/B/C overlap.

Instances

LegendChart VennDiagram

Chart VennDiagram

newVennDiagram :: VennDiagram