请问如下这个CART决策树代码哪里出问题了

import warnings
warnings.filterwarnings('ignore')
import numpy as np
import os
from sklearn.tree import export_graphviz

import matplotlib
import matplotlib.pyplot as plt
plt.rcParams['axes.labelsize'] = 14
plt.rcParams['xtick.labelsize'] = 12
plt.rcParams['ytick.labelsize'] = 12
from sklearn.tree import DecisionTreeClassifier
import pandas as pd
df = pd.read_excel(r"C:\Users\Administrator\Desktop\市场调研\新媒体.xlsx")
print(df)
data= df() #加载数据集
X = data[:,4:]
y = data.target
print(X)
print(y)
class_names=['Reasonable treatment','Lighten the burden','Convenient process','Reasonable payment']
feature_names=['Others','Non-Others']
clf=DecisionTreeClassifier(max_depth=3,random_state=234)
clf.fit(X,y)
##导出 dot 文件
dot_data = export_graphviz(
          clf,
          out_file="C:\\dot_data.dot",
          feature_names=feature_names,
          class_names=class_names,
          rounded=True,
          filled=True
          )

运行会出现如下问题

  File "C:\Users\Administrator\.spyder-py3\untitled0.py", line 16, in <module>
    data= df() #加载数据集

TypeError: 'DataFrame' object is not callable

请问一下，是哪里出错了呀？

data = df