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Description:

pyggplot 27

pyggplot is a Pythonic wrapper around the [R ggplot2 library](http://had.co.nz/ggplot2/).
It is based on a a straightforward take [Pandas](http://pandas.pydata.org/) data frames and shove them into [R](http://www.r-project.org/) via [rpy2](https://pypi.python.org/pypi/rpy2) approach.
## Examples
Please visit http://nbviewer.ipython.org/url/tyberiusprime.github.io/pyggplot/pyggplot%20samples.ipynb
## Installation
The easiest installation is via [PyPI](https://pypi.python.org/pypi).

$ pip install pyggplot

You may be required to update pandas, rpy2, so you may be required to run

$ pip install –upgrade pyggplot

## Usage

import pandas as pd
import numpy as np
import ggplot

df = pd.DataFrame({‘x’: np.random.rand(100),
‘y’: np.random.randn(100),
‘group’: [‘A’,’B’] * 50})

p = pyggplot.Plot(df)
p.add_scatter(‘x’,’y’, color=’group’)
p.render(‘output.png’)
## or if you want to use it in IPython Notebook
# p.render_notebook()

## Further usage
Takes a pandas.DataFrame object, then add layers with the various add_xyz
functions (e.g. add_scatter).
Refer to the ggplot documentation about the layers (geoms), and simply
replace geom_* with add_*.
See: http://docs.ggplot2.org/0.9.3.1/index.html
You do not need to separate aesthetics from values - the wrapper
will treat a parameter as value if and only if it is not a column name.
(so y = 0 is a value, color = ‘blue’ is a value - except if you have a column ‘blue’, then it is a column!.
And y = ‘value’ does not work, but that seems to be a ggplot issue).
When the DataFrame is passed to R:

row indices are turned into columns with ‘reset_index’,
multi level column indices are flattened by concatenating them with ‘ ‘, that is (X, ‘mean’) becomes ‘x mean’.

Error messages are not great - most of them translate to ‘one or more columns were not found’,
but they can appear as a lot of different actual messages such as

argument “env” is missing, with no default
object ‘y’ not found
object ‘dat_0’ not found
requires the following missing aesthetics: x
non numeric argument to binary operator

without actually quite pointing at what is strictly the offending value.
Also, the error appears when rendering (or printing in the [IPython Notebook](http://ipython.org/notebook.html)),
not when adding the layer.
## Open questions

the stat support is not great - it doesn’t easily map into pythonic objects. For now, do your stats in pandas - more powerful anyhow!
how could error messages be improved?

## Other ggplots’ for python

http://ggplot.yhathq.com/ is a port of ggplot2 for python based on matplotlib - unfortunatly not yet feature complete as of early 2015.
https://github.com/sirrice/pyplot is another wrapper for ggplot closer to R’s syntax, and does not rely on rpy2 - calls command line R.