報錯：
Aw, snap! We don't have an account for ''. Want to try again? You can authenticate with your email address or username. Sign in is not case sensitive. Don't have an account? plot.ly Questions? support@plot.ly
PlotlyError: Because you didn't supply a 'file_id' in the call, we're assuming you're trying to snag a figure from a url. You supplied the url, '', we expected it to start with 'https://plot.ly'. Run help on this function for more information.
解決辦法:在https://plot.ly/注冊賬戶，然后在plotly的credentials文件中設置用戶名和API_key，具體方法參見：https://plot.ly/python/getting-started/