Rpy2 and drawing pie diagram

Here is code that I come up with for drawing a pie diagram using rpy2. The function takes two lists. Function takes two lists: data contains frequencies and labels labels. The argument title set the title text of chart. Radius sets the radius of pie (max 1.0). Font size 1 is default, 1.5 is 50% bigger, 0.5 is 50% smaller. If file name is provided the chart will be saved to png file. Radius, font_size, and file name are optional parameters.

import rpy2.robjects as robjects
from rpy2.robjects.packages import importr

def draw_pie(data, labels, title, radius=0.8, font_size=1.0, file_name=None):

    total = 0
    for x in data: total = total + x

    labels_with_percentages = []
    for td, tl in zip(data, labels):
        percentage = 100.0 * float(td)/float(total)
        labels_with_percentages.append("%s %.1f%%" % (tl, percentage))

    l = robjects.StrVector(labels_with_percentages)
    d = robjects.IntVector(data)

    grdevices = importr('grDevices')
    if file_name:
        grdevices.png(file_name)
    font = robjects.r['par'](cex=font_size)
    robjects.r.pie(d,l, main=title, radius=radius)
    if file_name:
        grdevices.dev_off()

To use this we can do:

draw_pie([10,8],["Male", "Female"], "Sex", font_size=1.5, file_name="chart.png")