Metadata-Version: 1.0
Name: pycha
Version: 0.3.0
Summary: A library for making charts with Python
Home-page: http://www.lorenzogil.com/projects/pycha/
Author: Lorenzo Gil Sanchez
Author-email: lorenzo.gil.sanchez@gmail.com
License: LGPL 3
Description: .. contents::
        
        =====
        PyCha
        =====
        
        Pycha is a very simple Python package for drawing charts using the great
        `Cairo <http://www.cairographics.org/>`_ library. Its goals are:
        
        * Lightweight
        
        * Simple to use
        
        * Nice looking with default values
        
        * Customization
        
        It won't try to draw any possible chart on earth but draw the most common ones
        nicely. There are some other options you may want to look at like
        `pyCairoChart <http://bettercom.de/de/pycairochart>`_.
        
        Pycha is based on `Plotr <http://solutoire.com/plotr/>`_ which is based on
        `PlotKit <http://www.liquidx.net/plotkit/>`_. Both libraries are written in
        JavaScript and are great for client web programming. I needed the same for the
        server side so that's the reason I ported Plotr to Python. Now we can deliver
        charts to people with JavaScript disabled or embed them in PDF reports.
        
        Pycha is distributed under the terms of the `GNU Lesser General Public License
        <http://www.gnu.org/licenses/lgpl.html>`_.
        
        Documentation
        =============
        
        Installation
        ------------
        
        Pycha needs PyCairo to works since it uses the Cairo graphics library. If you
        use Linux you will probably already have it installed so you don't have to do
        anything. If you use Windows these are the recommended steps for installing
        PyCairo:
        
        1. Grab the latest PyCairo Windows installer from
        http://ftp.gnome.org/pub/GNOME/binaries/win32/pycairo/ You need to use the
        one that matches your Python version so take the one ending in -py2.4.exe
        for Python 2.4 or the one ending in -py2.5.exe for Python 2.5
        2. Install it in your Python environment (just follow the installation
        program instructions)
        3. Put the Cairo dlls inside the pycairo directory inside your site-packages
        directory or anywhere in your path. You can find the dlls at
        http://www.gimp.org/%7Etml/gimp/win32/downloads.html Go there and download
        the following packages:
        
        1. cairo.zip. You just need the libcairo-2.dll file inside that zip
        2. libpng.zip. You just need the libpng13.dll file inside that zip
        3. zlib.zip. You just need the zlib1.dll file inside that zip
        
        Pycha is distributed as a Python Egg so is quite easy to install. You just need
        to type the following command:
        
        easy_install pycha
        
        And Easy Install will go to the Cheeseshop and grab the last pycha for you. If
        will also install it for you at no extra cost :-)
        
        Tutorial
        --------
        
        Using pycha is quite simple. You always follow the same 5 simple steps:
        
        1. Create a Cairo surface to draw the chart on
        2. Build a list of data sets from which your chart will be created
        3. Customize the chart options.
        4. Create the chart, add the datasets and render it
        5. Save the results into a file or do whatever you want with the Cairo
        surface
        
        To create the Cairo surface you just need to say the type of surface and its
        dimensions:
        
        import cairo
        width, height = (500, 400)
        surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
        
        Then you should create your data set querying a database or any other data
        source::
        
        dataSet = (
        ('dataSet 1', ((0, 1), (1, 3), (2, 2.5))),
        ('dataSet 2', ((0, 2), (1, 4), (2, 3))),
        ('dataSet 3', ((0, 5), (1, 1), (2, 0.5))),
        )
        
        As you can see, each data set is a tuple where the first element is the name of
        the data set and the second is another tuple composed by points. Each point is a
        two-elements tuple, the first one is the x value and the second the y value.
        
        Not every chart uses all the information of a data set. For example, the Pie
        chart only uses the first point of each dataset and it only uses the y value of
        the point.
        
        Now you may want to specify some options so the chart can be customize changing
        its defaults values. To see the defaults you can check the
        pycha.chart.Chart.__init__ method in the source code. You can use regular
        dictionaries to define your options. For example, imagine you want to hide the
        legend and use a different color for the background::
        
        options = {
        'legend': {'hide': True},
        'background': {'color': '#f0f0f0'},
        }
        
        Now we are ready to instantiate the chart, add the data set and render it::
        
        import pycha.bar
        chart = pycha.bar.VerticalBarChart(surface, options)
        chart.addDataset(dataSet)
        chart.render()
        
        
        Right now you can choose among 4 different kind of charts:
        
        * Pie Charts (picha.pie.PieChart)
        * Vertical Bar Charts (picha.bar.VerticalBarChart)
        * Horizontal Bar Charts (picha.bar.HorizontalBarChart)
        * Line Charts (picha.bar.LineChart)
        
        Finally you can write the surface to a graphic file or anything you want using
        the cairo library::
        
        surface.write_to_png('output.png')
        
        That's it! You can see more examples in the examples directory of the source
        code.
        
        Development
        -----------
        
        You can get the last bleeding edge version of pycha by getting a checkout of
        the subversion repository::
        
        svn co http://www.lorenzogil.com/svn/pycha/trunk pycha
        
        
        
        Changes
        =======
        
        0.3.0 (2008-03-22)
        ------------------
        - Scattered charts
        - Chart titles
        - Axis labels and rotated ticks
        - Chart background and surface background
        - Automatically augment the light in large color schemes
        - Lots of bug fixes
        
        0.2.0 (2007-10-25)
        ------------------
        - Test suite
        - Python 2.4 compatibility (patch by Miguel Hernandez)
        - API docs
        - Small fixes
        
        0.1.0 (2007-10-17)
        ------------------
        - Initial release
        
Keywords: chart cairo
Platform: UNKNOWN
