import boto3
from StringIO import StringIO

def write_df_to_s3(df, s3_bucket, s3_key, encoding='utf-8', index=False, **kwargs):
    """
    Writes a pandas dataframe to a csv on AWS S3

    Arguments:
        df (pd.DataFrame): dataframe to write
        s3_bucket (str): s3 bucket name, e.g. "my-bucket"
        s3_key (str): s3 bucket key to write file as, e.g. "data/myfile.csv"
        kwargs: arguments to pass to pd.DataFrame.to_csv()
    """
    csv_buffer = StringIO()
    df.to_csv(csv_buffer, encoding=encoding, index=index, **kwargs)
    s3_resource = boto3.resource('s3')
    s3_resource.Object(s3_bucket, s3_key).put(Body=csv_buffer.getvalue())