在 python 中使用 df.loc 时出现 AssertionError
AssertionError when use df.loc in python
我创建了一个脚本来加载数据、检查 NA 值并填充所有 NA 值。这是我的代码：
import pandas as pd
def filter_df(merged_df, var_list):
ind = merged_df.Name.isin(var_list)
return merged_df[ind]
def pivot_df(df):
return df.pivot(index='Date', columns='Name', values=['Open', 'High', 'Low', 'Close'])
def validation_df(input, summary = False):
df = input.copy()
# na check
missing = df.isna().sum().sort_values(ascending=False)
percent_missing = ((missing / df.isnull().count()) * 100).sort_values(ascending=False)
missing_df = pd.concat([missing, percent_missing], axis=1, keys=['Total', 'Percent'], sort=False)
# fill na
columns = list(missing_df[missing_df['Total'] >= 1].reset_index()['index'])
for col in columns:
null_index = df.index[df[col].isnull() == True].tolist()
null_index.sort()
for ind in null_index:
if ind > 0:
print(df.loc[ind, col])
print(df.loc[ind - 1, col])
df.loc[ind, col] = df.loc[ind - 1, col]
if ind == 0:
df.loc[ind, col] = 0
# outliers check
count = []
for col in df.columns:
count.append(sum(df[col] > df[col].mean() + 2 * df[col].std()) + sum(df[col] < df[col].mean() - 2 * df[col].std()))
outliers_df = pd.DataFrame({'Columns': df.columns, 'Count': count}).sort_values(by = 'Count')
if summary == True:
print('missing value check:/n')
print(missing_df)
print('/n outliers check:/n')
print(outliers_df)
return df
def join_df(price_df, transaction_df, var_list):
price_df = filter_df(price_df, var_list)
price_df = pivot_df(price_df)
joined_df = transaction_df.merge(price_df, how = 'left', on = 'Date')
#joined_df = validation_df(joined_df)
return joined_df
token_path = 'https://raw.githubusercontent.com/Carloszone/Cryptocurrency_Research_project/main/datasets/1_token_df.csv'
transaction_path = 'https://raw.githubusercontent.com/Carloszone/Cryptocurrency_Research_project/main/datasets/transaction_df.csv'
var_list = ['Bitcoin', 'Ethereum', 'Golem', 'Solana']
token_df = pd.read_csv(token_path)
transaction_df = pd.read_csv(transaction_path)
df = join_df(token_df, transaction_df, var_list)
df = validation_df(df)
但是没有用。我检查了我的代码，发现这个问题来自 loc()。例如：
df = join_df(token_df, transaction_df, var_list)
print(df[df.columns[15]])
print(df.loc[1,df.columns[15]])
我得到的是：
0 NaN
1 NaN
2 NaN
3 NaN
4 NaN
..
2250 NaN
2251 NaN
2252 NaN
2253 NaN
2254 NaN
Name: (High, Solana), Length: 2255, dtype: float64
AssertionError Traceback (most recent call last)
<ipython-input-19-75f01cc22c9c> in <module>()
2
3 print(df[df.columns[15]])
----> 4 print(df.loc[1,df.columns[15]])
2 frames
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in __getitem__(self, key)
923 with suppress(KeyError, IndexError):
924 return self.obj._get_value(*key, takeable=self._takeable)
--> 925 return self._getitem_tuple(key)
926 else:
927 # we by definition only have the 0th axis
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in _getitem_tuple(self, tup)
1107 return self._multi_take(tup)
1108
-> 1109 return self._getitem_tuple_same_dim(tup)
1110
1111 def _get_label(self, label, axis: int):
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in _getitem_tuple_same_dim(self, tup)
807 # We should never have retval.ndim < self.ndim, as that should
808 # be handled by the _getitem_lowerdim call above.
--> 809 assert retval.ndim == self.ndim
810
811 return retval
AssertionError:
我不知道为什么df[column_name]可用，但是df.loc[index,columns_name]是错误的
你可以在 Colab 上查看我的代码：https://colab.research.google.com/drive/1Yg280JRwFayW1tdp4OJqTO5-X3dGsItB?usp=sharing
问题是您在一个不共享的列上合并两个 DataFrame（因为您旋转 price_df，日期列成为索引）。此外，日期列没有统一的格式，因此您必须使它们相同。将您的 join_df 函数替换为下面的函数，它将按预期工作。
我在必须添加的行上添加了注释。
def join_df(price_df, transaction_df, var_list):
price_df = filter_df(price_df, var_list)
price_df = pivot_df(price_df)
# After pivot the Date column is the index, and price_df has MultiIndex columns
# since we want to merge it with transaction_df, we need to first flatten the columns
price_df.columns = price_df.columns.map('.'.join)
# and reset_index so that we have the index as the Date column
price_df = price_df.reset_index()
# the Dates are formatted differently across the two DataFrames;
# one has the following format: '2016-01-01' and the other '2016/1/1'
# to have a uniform format, we convert the both Date columns to datetime objects
price_df['Date'] = pd.to_datetime(price_df['Date'])
transaction_df['Date'] = pd.to_datetime(transaction_df['Date'])
joined_df = transaction_df.merge(price_df, how = 'left', on = 'Date')
#joined_df = validation_df(joined_df)
return joined_df
输出：
Date total_transaction_count Volume gas_consumption \
0 2016-01-01 2665 NaN NaN
1 2016-01-02 4217 NaN NaN
2 2016-01-03 4396 NaN NaN
3 2016-01-04 4776 NaN NaN
4 2016-01-05 26649 NaN NaN
... ... ... ... ...
2250 2022-02-28 1980533 1.968686e+06 8.626201e+11
2251 2022-03-01 2013145 2.194055e+06 1.112079e+12
2252 2022-03-02 1987934 2.473327e+06 1.167615e+12
2253 2022-03-03 1973190 3.093248e+06 1.260826e+12
2254 2022-03-04 1861286 4.446204e+06 1.045814e+12
old_ave_gas_fee new_avg_gas_fee new_avg_base_fee \
0 0.000000e+00 0.000000e+00 0.000000e+00
1 0.000000e+00 0.000000e+00 0.000000e+00
2 0.000000e+00 0.000000e+00 0.000000e+00
3 0.000000e+00 0.000000e+00 0.000000e+00
4 0.000000e+00 0.000000e+00 0.000000e+00
... ... ... ...
2250 6.356288e-08 6.356288e-08 5.941877e-08
2251 5.368574e-08 5.368574e-08 4.982823e-08
2252 5.567472e-08 5.567472e-08 4.782055e-08
2253 4.763823e-08 4.763823e-08 4.140883e-08
2254 4.566440e-08 4.566440e-08 3.547666e-08
new_avg_priority_fee Open.Bitcoin Open.Ethereum ... High.Golem \
0 0.000000e+00 430.0 NaN ... NaN
1 0.000000e+00 434.0 NaN ... NaN
2 0.000000e+00 433.7 NaN ... NaN
3 0.000000e+00 430.7 NaN ... NaN
4 0.000000e+00 433.3 NaN ... NaN
... ... ... ... ... ...
2250 4.144109e-09 37707.2 2616.34 ... 0.48904
2251 3.857517e-09 43187.2 2922.44 ... 0.48222
2252 7.854179e-09 44420.3 2975.80 ... 0.47550
2253 6.229401e-09 NaN NaN ... NaN
2254 1.018774e-08 NaN NaN ... NaN
High.Solana Low.Bitcoin Low.Ethereum Low.Golem Low.Solana \
0 NaN 425.9 NaN NaN NaN
1 NaN 430.7 NaN NaN NaN
2 NaN 423.1 NaN NaN NaN
3 NaN 428.6 NaN NaN NaN
4 NaN 428.9 NaN NaN NaN
... ... ... ... ... ...
2250 NaN 37458.9 2574.12 0.41179 NaN
2251 NaN 42876.6 2858.54 0.45093 NaN
2252 NaN 43361.3 2914.70 0.43135 NaN
2253 NaN NaN NaN NaN NaN
2254 NaN NaN NaN NaN NaN
Close.Bitcoin Close.Ethereum Close.Golem Close.Solana
0 434.0 NaN NaN NaN
1 433.7 NaN NaN NaN
2 430.7 NaN NaN NaN
3 433.3 NaN NaN NaN
4 431.2 NaN NaN NaN
... ... ... ... ...
2250 43188.2 2922.50 0.47748 NaN
2251 44420.3 2975.81 0.47447 NaN
2252 43853.2 2952.47 0.43964 NaN
2253 NaN NaN NaN NaN
2254 NaN NaN NaN NaN
[2255 rows x 24 columns]
我创建了一个脚本来加载数据、检查 NA 值并填充所有 NA 值。这是我的代码：
import pandas as pd
def filter_df(merged_df, var_list):
ind = merged_df.Name.isin(var_list)
return merged_df[ind]
def pivot_df(df):
return df.pivot(index='Date', columns='Name', values=['Open', 'High', 'Low', 'Close'])
def validation_df(input, summary = False):
df = input.copy()
# na check
missing = df.isna().sum().sort_values(ascending=False)
percent_missing = ((missing / df.isnull().count()) * 100).sort_values(ascending=False)
missing_df = pd.concat([missing, percent_missing], axis=1, keys=['Total', 'Percent'], sort=False)
# fill na
columns = list(missing_df[missing_df['Total'] >= 1].reset_index()['index'])
for col in columns:
null_index = df.index[df[col].isnull() == True].tolist()
null_index.sort()
for ind in null_index:
if ind > 0:
print(df.loc[ind, col])
print(df.loc[ind - 1, col])
df.loc[ind, col] = df.loc[ind - 1, col]
if ind == 0:
df.loc[ind, col] = 0
# outliers check
count = []
for col in df.columns:
count.append(sum(df[col] > df[col].mean() + 2 * df[col].std()) + sum(df[col] < df[col].mean() - 2 * df[col].std()))
outliers_df = pd.DataFrame({'Columns': df.columns, 'Count': count}).sort_values(by = 'Count')
if summary == True:
print('missing value check:/n')
print(missing_df)
print('/n outliers check:/n')
print(outliers_df)
return df
def join_df(price_df, transaction_df, var_list):
price_df = filter_df(price_df, var_list)
price_df = pivot_df(price_df)
joined_df = transaction_df.merge(price_df, how = 'left', on = 'Date')
#joined_df = validation_df(joined_df)
return joined_df
token_path = 'https://raw.githubusercontent.com/Carloszone/Cryptocurrency_Research_project/main/datasets/1_token_df.csv'
transaction_path = 'https://raw.githubusercontent.com/Carloszone/Cryptocurrency_Research_project/main/datasets/transaction_df.csv'
var_list = ['Bitcoin', 'Ethereum', 'Golem', 'Solana']
token_df = pd.read_csv(token_path)
transaction_df = pd.read_csv(transaction_path)
df = join_df(token_df, transaction_df, var_list)
df = validation_df(df)
但是没有用。我检查了我的代码，发现这个问题来自 loc()。例如：
df = join_df(token_df, transaction_df, var_list)
print(df[df.columns[15]])
print(df.loc[1,df.columns[15]])
我得到的是：
0 NaN
1 NaN
2 NaN
3 NaN
4 NaN
..
2250 NaN
2251 NaN
2252 NaN
2253 NaN
2254 NaN
Name: (High, Solana), Length: 2255, dtype: float64
AssertionError Traceback (most recent call last)
<ipython-input-19-75f01cc22c9c> in <module>()
2
3 print(df[df.columns[15]])
----> 4 print(df.loc[1,df.columns[15]])
2 frames
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in __getitem__(self, key)
923 with suppress(KeyError, IndexError):
924 return self.obj._get_value(*key, takeable=self._takeable)
--> 925 return self._getitem_tuple(key)
926 else:
927 # we by definition only have the 0th axis
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in _getitem_tuple(self, tup)
1107 return self._multi_take(tup)
1108
-> 1109 return self._getitem_tuple_same_dim(tup)
1110
1111 def _get_label(self, label, axis: int):
/usr/local/lib/python3.7/dist-packages/pandas/core/indexing.py in _getitem_tuple_same_dim(self, tup)
807 # We should never have retval.ndim < self.ndim, as that should
808 # be handled by the _getitem_lowerdim call above.
--> 809 assert retval.ndim == self.ndim
810
811 return retval
AssertionError:
我不知道为什么df[column_name]可用，但是df.loc[index,columns_name]是错误的
你可以在 Colab 上查看我的代码：https://colab.research.google.com/drive/1Yg280JRwFayW1tdp4OJqTO5-X3dGsItB?usp=sharing
问题是您在一个不共享的列上合并两个 DataFrame（因为您旋转 price_df，日期列成为索引）。此外，日期列没有统一的格式，因此您必须使它们相同。将您的 join_df 函数替换为下面的函数，它将按预期工作。
我在必须添加的行上添加了注释。
def join_df(price_df, transaction_df, var_list):
price_df = filter_df(price_df, var_list)
price_df = pivot_df(price_df)
# After pivot the Date column is the index, and price_df has MultiIndex columns
# since we want to merge it with transaction_df, we need to first flatten the columns
price_df.columns = price_df.columns.map('.'.join)
# and reset_index so that we have the index as the Date column
price_df = price_df.reset_index()
# the Dates are formatted differently across the two DataFrames;
# one has the following format: '2016-01-01' and the other '2016/1/1'
# to have a uniform format, we convert the both Date columns to datetime objects
price_df['Date'] = pd.to_datetime(price_df['Date'])
transaction_df['Date'] = pd.to_datetime(transaction_df['Date'])
joined_df = transaction_df.merge(price_df, how = 'left', on = 'Date')
#joined_df = validation_df(joined_df)
return joined_df
输出：
Date total_transaction_count Volume gas_consumption \
0 2016-01-01 2665 NaN NaN
1 2016-01-02 4217 NaN NaN
2 2016-01-03 4396 NaN NaN
3 2016-01-04 4776 NaN NaN
4 2016-01-05 26649 NaN NaN
... ... ... ... ...
2250 2022-02-28 1980533 1.968686e+06 8.626201e+11
2251 2022-03-01 2013145 2.194055e+06 1.112079e+12
2252 2022-03-02 1987934 2.473327e+06 1.167615e+12
2253 2022-03-03 1973190 3.093248e+06 1.260826e+12
2254 2022-03-04 1861286 4.446204e+06 1.045814e+12
old_ave_gas_fee new_avg_gas_fee new_avg_base_fee \
0 0.000000e+00 0.000000e+00 0.000000e+00
1 0.000000e+00 0.000000e+00 0.000000e+00
2 0.000000e+00 0.000000e+00 0.000000e+00
3 0.000000e+00 0.000000e+00 0.000000e+00
4 0.000000e+00 0.000000e+00 0.000000e+00
... ... ... ...
2250 6.356288e-08 6.356288e-08 5.941877e-08
2251 5.368574e-08 5.368574e-08 4.982823e-08
2252 5.567472e-08 5.567472e-08 4.782055e-08
2253 4.763823e-08 4.763823e-08 4.140883e-08
2254 4.566440e-08 4.566440e-08 3.547666e-08
new_avg_priority_fee Open.Bitcoin Open.Ethereum ... High.Golem \
0 0.000000e+00 430.0 NaN ... NaN
1 0.000000e+00 434.0 NaN ... NaN
2 0.000000e+00 433.7 NaN ... NaN
3 0.000000e+00 430.7 NaN ... NaN
4 0.000000e+00 433.3 NaN ... NaN
... ... ... ... ... ...
2250 4.144109e-09 37707.2 2616.34 ... 0.48904
2251 3.857517e-09 43187.2 2922.44 ... 0.48222
2252 7.854179e-09 44420.3 2975.80 ... 0.47550
2253 6.229401e-09 NaN NaN ... NaN
2254 1.018774e-08 NaN NaN ... NaN
High.Solana Low.Bitcoin Low.Ethereum Low.Golem Low.Solana \
0 NaN 425.9 NaN NaN NaN
1 NaN 430.7 NaN NaN NaN
2 NaN 423.1 NaN NaN NaN
3 NaN 428.6 NaN NaN NaN
4 NaN 428.9 NaN NaN NaN
... ... ... ... ... ...
2250 NaN 37458.9 2574.12 0.41179 NaN
2251 NaN 42876.6 2858.54 0.45093 NaN
2252 NaN 43361.3 2914.70 0.43135 NaN
2253 NaN NaN NaN NaN NaN
2254 NaN NaN NaN NaN NaN
Close.Bitcoin Close.Ethereum Close.Golem Close.Solana
0 434.0 NaN NaN NaN
1 433.7 NaN NaN NaN
2 430.7 NaN NaN NaN
3 433.3 NaN NaN NaN
4 431.2 NaN NaN NaN
... ... ... ... ...
2250 43188.2 2922.50 0.47748 NaN
2251 44420.3 2975.81 0.47447 NaN
2252 43853.2 2952.47 0.43964 NaN
2253 NaN NaN NaN NaN
2254 NaN NaN NaN NaN
[2255 rows x 24 columns]