Convert string to float error in pandas machine learning

For my machine learning code, I have some unknown values with '?' in my csv file. So, I am trying to replace them with 'Nan' but it throws some error. The following code is for the replacement of '?' that I have used. Can anyone please solve this?
Thanks in advance !

import numpy
import pandas as pd
import matplotlib as plot
import numpy as np
df = pd.read_csv('cdk.csv')
x=df.iloc[:,0:24].values
y=df.iloc[:,24].values
from sklearn.preprocessing import Imputer
imputer = Imputer(missing_values='NaN', strategy='most_frequent', axis =0,copy=False)
imputer = imputer.fit(x[:,0:5])
imputer.fit_transform(x[:,0:5])

imputer = Imputer(missing_values='normal', strategy='mode', axis =0,copy=False)
imputer = imputer.fit(x[:,5:7])
imputer.fit_transform(x[:,5:7])


This is what error it throws,

Traceback (most recent call last):
File "kidney.py", line 10, in <module>
imputer = imputer.fit(x[:,0:5])
File "C:UsersYAASHIAppDataLocalProgramsPythonPython36libsite-packagessklearnpreprocessingimputation.py", line 155, in fit
force_all_finite=False)
File "C:UsersYAASHIAppDataLocalProgramsPythonPython36libsite-packagessklearnutilsvalidation.py", line 433, in check_array
array = np.array(array, dtype=dtype, order=order, copy=copy)
ValueError: could not convert string to float: '?'


Link for the csv file

ValueError

?

?

?

1 Answer
1

If you want to replace all ? strings with NaN, do this:

?

df.replace('?', np.nan, inplace=True)


Or better yet, load them as NaN as you read the CSV:

df = pd.read_csv('cdk.csv', na_values=['?'])


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