**之后的MetaSerialisable对象参数必须是映射，而不是unicode

Question

尝试将此样式器对象转换为xlsx表：

 avg.style.background_gradient(cmap='RdYlGn',low=.09,high=.18,axis=1).to_excel('test.xlsx',engine='xlsxwriter')

然而，我收到错误：

 TypeError: MetaSerialisable object argument after ** must be a mapping, not unicode

当我尝试时：

 avg.style.background_gradient({'cmap':'RdYlGn'},low=.09,high=.18,axis=1).to_excel('test.xlsx',engine='xlsxwriter')

TypeError: ("unhashable type: 'dict'", u'occurred at index (Gain/Expsr%, 5)')

这里有一个，没有背景渐变输出：

writer = pd.ExcelWriter('usher.xlsx')
df.style.background_gradient(cmap='RdYlGn').to_excel(writer,engine='openpyxl')
writer.save()