pandas报错：KeyError:

Posted 2023-05-01

参考技术A

使用pandas读取.csv文件，使用df[\'列名\']的时候，总是报如下错误。
.csv文件如下：

Traceback (most recent call last):
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\indexes\\base.py", line 2393, in get_loc
return self._engine.get_loc(key)
File "pandas_libs\\index.pyx", line 132, in pandas._libs.index.IndexEngine.get_loc (pandas_libs\\index.c:5239)
File "pandas_libs\\index.pyx", line 154, in pandas._libs.index.IndexEngine.get_loc (pandas_libs\\index.c:5085)
File "pandas_libs\\hashtable_class_helper.pxi", line 1207, in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas_libs\\hashtable.c:20405)
File "pandas_libs\\hashtable_class_helper.pxi", line 1215, in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas_libs\\hashtable.c:20359)
KeyError: \'交易日期\'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "D:/Quant/Practice/Code/xbx_stock_2019/program/pandas基础/5_缺失处理.py", line 25, in <module>
index = df[df[\'交易日期\'].isin([\'2019-03-01\'])].index
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\frame.py", line 2062, in getitem
return self._getitem_column(key)
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\frame.py", line 2069, in _getitem_column
return self._get_item_cache(key)
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\generic.py", line 1534, in _get_item_cache
values = self._data.get(item)
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\internals.py", line 3590, in get
loc = self.items.get_loc(item)
File "C:\\Users\\zhangheng\\anaconda3\\envs\\py36\\lib\\site-packages\\pandas\\core\\indexes\\base.py", line 2395, in get_loc
return self._engine.get_loc(self._maybe_cast_indexer(key))
File "pandas_libs\\index.pyx", line 132, in pandas._libs.index.IndexEngine.get_loc (pandas_libs\\index.c:5239)
File "pandas_libs\\index.pyx", line 154, in pandas._libs.index.IndexEngine.get_loc (pandas_libs\\index.c:5085)
File "pandas_libs\\hashtable_class_helper.pxi", line 1207, in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas_libs\\hashtable.c:20405)
File "pandas_libs\\hashtable_class_helper.pxi", line 1215, in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas_libs\\hashtable.c:20359)
KeyError: \'交易日期\'

Process finished with exit code 1

import pandas as pd # 将pandas作为第三方库导入，我们一般为pandas取一个别名叫做pd

pd.set_option(\'expand_frame_repr\', False) # 当列太多时清楚展示

df = pd.read_csv(
r\'D:\\Quant\\Practice\\Code\\xbx_stock_2019\\data\\a_stock_201903.csv\',
encoding=\'gbk\',
skiprows=1
)
在导入数据时，skiprows=1，即即读取.csv文件时，跳过了第一行的列名，没有读取列名，你使用 df[\'列名\'] 就会报错

Pandas - KeyError: '[] not in index' 训练 Keras 模型时

【中文标题】Pandas - KeyError: \'[] not in index\' 训练 Keras 模型时

【英文标题】：Pandas - KeyError: '[] not in index' when training a Keras modelPandas - KeyError: '[] not in index' 训练 Keras 模型时

【发布时间】：2018-01-10 18:22:07

【问题描述】：

我正在尝试根据我的数据集中的部分特征来训练 Keras 模型。我已经加载了数据集并提取了如下特征：

train_data = pd.read_csv('../input/data.csv')

X = train_data.iloc[:, 0:30]
Y = train_data.iloc[:,30]

# Code for selecting the important features automatically (removed) ...    

# Selectintg important features 14,17,12,11,10,16,18,4,9,3
X = train_data.reindex(columns=['V14','V17','V12','V11','V10','V16','V18','V4','V9','V3'])
print(X.shape[1]) # -> 10

但是当我调用 fit 方法时：

# Fit the model
history = model.fit(X, Y, validation_split=0.33, epochs=10, batch_size=10, verbose=0, callbacks=[early_stop])

我收到以下错误：

KeyError: '[3 2 5 1 0 4] not in index'

我错过了什么？

【问题讨论】：

检查this thread。

【参考方案1】：

keras 期望模型输入是 numpy 数组 - 而不是 pandas.DataFrames。试试：

X = train_data.iloc[:, 0:30].as_matrix()
Y = train_data.iloc[:,30].as_matrix()

由于as_matrix 方法将pandas.DataFrame 转换为numpy.array。