在尝试拟合之前，我彻底清理了我的数据框，并确保整个数据框没有inf或NaN值，并且由完全非null的float64值组成。但是，我仍然使用np.isinf（），df.isnull（）。sum（）和df.info（）方法对此进行了冗余验证。我的所有研究表明，具有相同问题的其他人在其数据框中具有NaN，inf或对象数据类型。在我的情况下，情况并非如此。最后，我找到了一个模糊的case，它使用此代码找到了解决方案：
df = df.apply(lambda x: pd.to_numeric(x,errors='ignore'))
这对我的情况没有帮助。如何解决此ValueError异常？
from sklearn.neighbors import KNeighborsRegressor
from sklearn.metrics import mean_squared_error
import pandas as pd
import numpy as np
# Read csv file and assign column names
headers=['symboling','normalized_losses','make','fuel_type','aspiration','num_of_doors',
'body_style','drive_wheels','engine_location','wheel_base','length','width',
'height','curb_weight','engine_type','num_of_cylinders','engine_size','fuel_system',
'bore','stroke','compression_ratio','horsepower','peak_rpm','city_mpg','highway_mpg',
'price']
cars = pd.read_csv('imports-85.data.txt', names=headers)
# Select only the columns with continuous values from - https://archive.ics.uci.edu/ml/machine-learning-databases/autos/imports-85.names
continuous_values_cols = ['normalized_losses', 'wheel_base', 'length', 'width', 'height', 'curb_weight',
'bore', 'stroke', 'compression_ratio', 'horsepower', 'peak_rpm', 'city_mpg', 'highway_mpg', 'price']
numeric_cars = cars[continuous_values_cols].copy()
# Clean Data Set by Convert missing values (?) with np.NaN then set the type to float
numeric_cars.replace(to_replace='?', value=np.nan, inplace=True)
numeric_cars = numeric_cars.astype('float')
# Because the column we're trying to predict is 'price', any row were price is NaN will be removed."
numeric_cars.dropna(subset=['price'], inplace=True)
# All remaining NaN's will be filled with the mean of its respective column
numeric_cars = numeric_cars.fillna(numeric_cars.mean())
# Create training feature list and k value list
test_features = numeric_cars.columns.tolist()
predictive_feature = 'price'
test_features.remove(predictive_feature)
k_values = [x for x in range(10) if x/2 != round(x/2)]
# Normalize columns
numeric_cars_normalized = numeric_cars[test_features].copy()
numeric_cars_normalized = numeric_cars_normalized/ numeric_cars.max()
numeric_cars_normalized[predictive_feature] = numeric_cars[predictive_feature].copy()
def knn_train_test(df, train_columns, predict_feature, k_value):
# Randomly resorts the DataFrame to mitigate sampling bias
np.random.seed(1)
df = df.loc[np.random.permutation(len(df))]
# Split the DataFrame into ~75% train / 25% test data sets
split_integer = round(len(df) * 0.75)
train_df = df.iloc[0:split_integer]
test_df = df.iloc[split_integer:]
train_features = train_df[train_columns]
train_target = train_df[predict_feature]
# Trains the model
knn = KNeighborsRegressor(n_neighbors=k_value)
knn.fit(train_features, train_target)
# Test the model & return calculate mean square error
predictions = knn.predict(test_df[train_columns])
print("predictions")
mse = mean_squared_error(y_true=test_df[predict_feature], y_pred=predictions)
return mse
# instantiate mse dict
mse_dict = {}
# test each feature and do so with a range of k values
# in an effot to determine the optimal training feature and k value
for feature in test_features:
mse = [knn_train_test(numeric_cars_normalized,feature, predictive_feature, k) for k in k_values]
mse_dict[feature] = mse
print(mse_dict)
这是完整的错误追溯：
C:\ProgramData\Anaconda3\lib\site-packages\sklearn\utils\validation.py:395: DeprecationWarning: Passing 1d arrays as data is deprecated in 0.17 and will raise ValueError in 0.19. Reshape your data either using X.reshape(-1, 1) if your data has a single feature or X.reshape(1, -1) if it contains a single sample.
DeprecationWarning)
Traceback (most recent call last):
File "C:\DATAQUEST\06_MachineLearning\01_ML_Fundamentals\06_GuidedProject_PredictingCarPrices\PredictingCarPrices.py", line 76, in <module>
mse = [knn_train_test(numeric_cars_normalized,feature, predictive_feature, k) for k in k_values]
File "C:\DATAQUEST\06_MachineLearning\01_ML_Fundamentals\06_GuidedProject_PredictingCarPrices\PredictingCarPrices.py", line 76, in <listcomp>
mse = [knn_train_test(numeric_cars_normalized,feature, predictive_feature, k) for k in k_values]
File "C:\DATAQUEST\06_MachineLearning\01_ML_Fundamentals\06_GuidedProject_PredictingCarPrices\PredictingCarPrices.py", line 60, in knn_train_test
knn.fit(train_features, train_target)
File "C:\ProgramData\Anaconda3\lib\site-packages\sklearn\neighbors\base.py", line 741, in fit
X, y = check_X_y(X, y, "csr", multi_output=True)
File "C:\ProgramData\Anaconda3\lib\site-packages\sklearn\utils\validation.py", line 521, in check_X_y
ensure_min_features, warn_on_dtype, estimator)
File "C:\ProgramData\Anaconda3\lib\site-packages\sklearn\utils\validation.py", line 407, in check_array
_assert_all_finite(array)
File "C:\ProgramData\Anaconda3\lib\site-packages\sklearn\utils\validation.py", line 58, in _assert_all_finite
" or a value too large for %r." % X.dtype)
ValueError: Input contains NaN, infinity or a value too large for dtype('float64').
以下是我用来验证我的DataFrame中没有NaN或inf值的代码和输出：
# Verify data for NaN and inf
print(len(numeric_cars_normalized))
# 201
print(numeric_cars_normalized.info())
# <class 'pandas.core.frame.DataFrame'>
# Int64Index: 201 entries, 0 to 204
# Data columns (total 14 columns):
# bore 201 non-null float64
# city_mpg 201 non-null float64
# compression_ratio 201 non-null float64
# curb_weight 201 non-null float64
# height 201 non-null float64
# highway_mpg 201 non-null float64
# horsepower 201 non-null float64
# length 201 non-null float64
# normalized_losses 201 non-null float64
# peak_rpm 201 non-null float64
# price 201 non-null float64
# stroke 201 non-null float64
# wheel_base 201 non-null float64
# width 201 non-null float64
# dtypes: float64(14)
# memory usage: 23.6 KB
# None
print(numeric_cars_normalized.isnull().sum())
# bore 0
# city_mpg 0
# compression_ratio 0
# curb_weight 0
# height 0
# highway_mpg 0
# horsepower 0
# length 0
# normalized_losses 0
# peak_rpm 0
# price 0
# stroke 0
# wheel_base 0
# width 0
# dtype: int64
# The loop below, essentially does the same as the above
# verification, but using different methods
# the purpose is to prove there's no nan or inf in my data set
index = []
NaN_counter = []
inf_counter = []
for col in numeric_cars_normalized.columns:
index.append(col)
# inf counter
col_isinf = np.isinf(numeric_cars_normalized[col])
if col_isinf.value_counts().index[0] == False:
inf_counter.append(col_isinf.value_counts()[0])
# nan counter
col_isnan = np.isnan(numeric_cars_normalized[col])
if col_isnan.value_counts().index[0] == False:
NaN_counter.append(col_isnan.value_counts()[0])
data_check = {'NOT_NaN_count': NaN_counter, 'NOT_inf_count': inf_counter}
data_verification = pd.DataFrame(data=data_check, index=index)
print(data_verification)
# NOT_NaN_count NOT_inf_count
# bore 201 201
# city_mpg 201 201
# compression_ratio 201 201
# curb_weight 201 201
# height 201 201
# highway_mpg 201 201
# horsepower 201 201
# length 201 201
# normalized_losses 201 201
# peak_rpm 201 201
# price 201 201
# stroke 201 201
# wheel_base 201 201
# width 201 201
我可能已经发现了问题，但仍然不确定如何修复它。
# Here's a another methodology for extra redudnant data checking
index = []
NaN_counter = []
inf_counter = []
for col in numeric_cars_normalized.columns:
index.append(col)
inf_counter.append(np.any(np.isfinite(numeric_cars_normalized[col])))
NaN_counter.append(np.any(np.isnan(numeric_cars_normalized[col])))
data_check = {'Any_NaN': NaN_counter, 'Any_inf': inf_counter}
data_verification = pd.DataFrame(data=data_check, index=index)
print(data_verification)
Any_NaN Any_inf
# bore False True
# city_mpg False True
# compression_ratio False True
# curb_weight False True
# height False True
# highway_mpg False True
# horsepower False True
# length False True
# normalized_losses False True
# peak_rpm False True
# price False True
# stroke False True
# wheel_base False True
# width False True
很明显我的DataSet中有inf，但我不确定为什么或如何修复它。
答案 0 :(得分：2)
通过评论这两行，您似乎遇到的问题来自于您正在进行的排列：
# np.random.seed(1)
# df = df.loc[np.random.permutation(len(df))]
这是因为当您清理数据时，最终只有204行来自204行。通过调试你提供给knn函数的数据帧，你可以发现，一旦数字_cars_normalized被置换，所有列中的三行现在都是'nan'。
并重新运行代码，您将获得结果。但是你应该做一些额外的改变，因为knn可以更好地使用数组，你应该将数据帧（系列）更改为具有正确维度的值，然后使用它们进行操作。在您的特定情况下，所有这些都是系列，您可以通过以下方式更改它们：
series.values.reshape(-1, 1)
以下是包含所有更改的knn函数： def knn_train_test（df，train_columns，predict_feature，k_value）：
#print(train_columns, k_value)
# Randomly resorts the DataFrame to mitigate sampling bias
#np.random.seed(1)
#df = df.loc[np.random.permutation(len(df))]
# Split the DataFrame into ~75% train / 25% test data sets
split_integer = round(len(df) * 0.75)
train_df = df.iloc[0:split_integer]
test_df = df.iloc[split_integer:]
train_features = train_df[train_columns].values.reshape(-1, 1)
train_target = train_df[predict_feature].values.reshape(-1, 1)
# Trains the model
knn = KNeighborsRegressor(n_neighbors=k_value)
knn.fit(train_features, train_target)
# Test the model & return calculate mean square error
predictions = knn.predict(test_df[train_columns].values.reshape(-1, 1))
print("predictions")
mse = mean_squared_error(y_true=test_df[predict_feature], y_pred=predictions)
return mse
有了这个，如果我得到了正确的输入文件，这就是我得到的：
predictions
{'normalized_losses': [100210405.34, 116919980.22444445, 88928383.280000001, 62378305.931836732, 65695537.133086421], 'wheel_base': [10942945.5, 31106845.595555563, 34758670.590399988, 29302177.901632652, 25464306.165925924], 'length': [71007156.219999999, 37635782.111111119, 33676038.287999995, 29868192.295918364, 22553474.111604933], 'width': [42519394.439999998, 25956086.771111108, 15199079.0744, 10443175.389795918, 8440465.6864197534], 'height': [117942530.56, 62910880.079999998, 41771068.588, 33511475.561224483, 31537852.588641971], 'curb_weight': [14514970.42, 6103365.4644444454, 6223489.0728000011, 7282828.3632653067, 6884187.4446913591], 'bore': [57147986.359999999, 88529631.346666679, 68063251.098399997, 58753168.154285707, 42950965.435555562], 'stroke': [145522819.16, 98024560.913333327, 61229681.429599993, 36452809.841224492, 25989788.846172832], 'compression_ratio': [93309449.939999998, 18108906.400000002, 30175663.952, 44964197.869387761, 39926111.747407407], 'horsepower': [25158775.920000002, 17656603.506666664, 13804482.193600001, 15772395.163265305, 14689078.471851852], 'peak_rpm': [169310760.66, 86360741.248888895, 51905953.367999993, 46999120.435102046, 45218343.222716056], 'city_mpg': [15467849.460000001, 12237327.542222224, 10855581.140000001, 11479257.790612245, 11047557.746419754], 'highway_mpg': [17384289.579999998, 15877936.197777782, 7720502.6856000004, 6315372.4963265313, 7118970.4081481481]}