Accessing Data Frame From Geom

[stefaneng]

I don't know if this is possible, but I ran into a problem when trying to implement geom_boxplot, see pull request #39. I have the code commented to showcase the problem I am running into. Hopefully I am not just overlooking some simple way to access the original data frame passed into ggplot(...)

My goal is to be able to pass the whole data frame into:

http://pandas.pydata.org/pandas-docs/stable/visualization.html#box-plotting

as this is much simpler that trying to implement multiple box plots with

http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.boxplot

[jhaynes]

Doing something like this works... but produces a blank plot first... haven't sorted out why.

class geom_boxplot(geom):
    VALID_AES = ['y', 'lower','middle','upper','x','ymax','ymin','alpha',
                 'colour','color','fill','linetype','shape','size','weight']


    def plot_layer(self, layer):
        layer = {k: v for k, v in layer.items() if k in self.VALID_AES}
        layer.update(self.manual_aes)

        # Option 1 (No Pandas)

        # Boxplot takes in an array or sequence of vectors
        # The goal is to group the 'y' values by grouped 'x'
        # Then take the transpose and give it to plt.boxplot(**layer)
        # If we do not have a y value, no need to change anything
        #        if "y" in layer:
        # list(set([...])) just gets unique elements
        #           unique = list(set(layer["x"]))            
        # Group y values in len(x) arrays, having values y.x
        # Store it back in x as a transpose.            
        #          pass

        # plt.boxplot(**layer)
        # Option 2 With Pandas and DataFrame.boxplot()
        # Need access to the DataFrame passed to ggplot(..)
        df = DataFrame({'y': layer['y']})
        if 'x' in layer:
            layer['by'] = 'x'
            df['x'] = layer['x']
            del layer['x']
        if 'y' in layer:
            layer['column'] = 'y'
            del layer['y']
        df.boxplot(**layer)

[glamp]

take a look at how geom_bar works. i think you can piggy-back off of that.

[jhaynes]

Thanks, geom_bar looks like a good place to start and avoiding deep coupling with pandas is probably not a terrible idea.

This is sort off topic, but is there a reason why you opted to pass the values from aes around rather than the data frame and its column names?

[glamp]

Largely b/c the geoms have aes defined on an individual basis. That said, I don't think theres any reason data frames wouldn't work.

On Oct 25, 2013, at 9:38 AM, jhaynes notifications@github.com wrote:
Thanks, geom_bar looks like a good place to start and avoiding deep coupling with pandas is probably not a terrible idea.

This is sort off topic, but is there a reason why you opted to pass the values from aes around rather than the data frame and its column names?

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[glamp]

thanks to @JanSchulz for this one!