图例在Python中无法正常工作

导入matplotlib.pyplot as plt导入numpy as np导入xlrd导入xlwt导入pandas作为pd

wb = xlrd.open_workbook('Scatter plot.xlsx')

sh1 = wb.sheet_by_name('T180')
sh2=wb.sheet_by_name("T181")
sh3=wb.sheet_by_name("T182")
sh4=wb.sheet_by_name("T183")
sh5=wb.sheet_by_name("T189")

x= np.array([sh1.col_values(1, start_rowx=51, end_rowx=301)])
y= np.array([sh1.col_values(2, start_rowx=51, end_rowx=315)])

x1= np.array(sh2.col_values(1, start_rowx=50, end_rowx=298))
y1= np.array(sh2.col_values(2, start_rowx=50, end_rowx=298))

plt.style.use('ggplot')
fn ="C:\Users\M15-1478\Desktop\python\Scatter plot.xlsx"
sheetname = 'T181'
df = pd.read_excel(fn, sheetname=sheetname, skiprows=47,    parse_cols='B:C').dropna(how='any')
df.ix[df.eval('0 <= GrvX <= 1000'), 'GrvX'] -= 150
df.ix[df.eval('1000 < GrvX <= 2000'), 'GrvX'] -= 50
df.ix[df.eval('2000 < GrvX'), 'GrvX'] -= 30

# customize Y-values
df.ix[df.eval('0 <= GrvY <= 1000'), 'GrvY'] += 30

print df
df.plot(x='GrvX', y='GrvY',  linestyle='no line', marker="o",  label="Corrected T182")
plt.plot(x,y, "gs", label="T181")
plt.plot(x1,y1, "bx", label="T182")
plt.legend(loc=0)
plt.show()

除第一个图例（“更正的T182”）外，图例未正确显示。我尝试了很多方法。我怎么解决这个问题？我在这里附上我有问题的照片。我还附上了数据文件，以方便您使用。提前致谢。资料档案