Python Sklearn "ValueError: Classification metrics can't handle a mix of multiclass-multioutput and binary targets" error - pandas

Question

I have already visited this answer but didn't understand.
I don't get this error when I use test_train_split function for using the same dateset for testing and training.
But when I try to use different csv files for testing and training I get this error.
link to titanic kaggle competition
Can Someone please explain why I am I getting this error?
from sklearn.linear_model import LogisticRegression
logreg=LogisticRegression()
logreg.fit(df,survived_df)
predictions=logreg.predict(test)
from sklearn.metrics import accuracy_score
accuracy=accuracy_score(test_survived,predictions) #error here Value Error ""ValueError: Classification metrics can't handle a mix of multiclass-multioutput and binary targets""
print(accuracy)
Full Error
ValueError Traceback (most recent call last)
<ipython-input-243-89c8ae1a928d> in <module>
----> 1 logreg.score(test,test_survived)
2
~/mldl/kaggle_practice/titanic_pilot/venv/lib64/python3.8/site-packages/sklearn/base.py in score(self, X, y, sample_weight)
497 """
498 from .metrics import accuracy_score
--> 499 return accuracy_score(y, self.predict(X), sample_weight=sample_weight)
500
501 def _more_tags(self):
~/mldl/kaggle_practice/titanic_pilot/venv/lib64/python3.8/site-packages/sklearn/utils/validation.py in inner_f(*args, **kwargs)
70 FutureWarning)
71 kwargs.update({k: arg for k, arg in zip(sig.parameters, args)})
---> 72 return f(**kwargs)
73 return inner_f
74
~/mldl/kaggle_practice/titanic_pilot/venv/lib64/python3.8/site-packages/sklearn/metrics/_classification.py in accuracy_score(y_true, y_pred, normalize, sample_weight)
185
186 # Compute accuracy for each possible representation
--> 187 y_type, y_true, y_pred = _check_targets(y_true, y_pred)
188 check_consistent_length(y_true, y_pred, sample_weight)
189 if y_type.startswith('multilabel'):
~/mldl/kaggle_practice/titanic_pilot/venv/lib64/python3.8/site-packages/sklearn/metrics/_classification.py in _check_targets(y_true, y_pred)
88
89 if len(y_type) > 1:
---> 90 raise ValueError("Classification metrics can't handle a mix of {0} "
91 "and {1} targets".format(type_true, type_pred))
92
ValueError: Classification metrics can't handle a mix of multiclass-multioutput and binary targets
Full Code
df=pd.read_csv('data/train.csv')
test=pd.read_csv('data/test.csv')
test_survived=pd.read_csv('data/gender_submission.csv')
plt.figure(5)
df=df.drop(columns=['Name','SibSp','Ticket','Cabin','Parch','Embarked'])
test=test.drop(columns=['Name','SibSp','Ticket','Cabin','Parch','Embarked'])
sns.heatmap(df.isnull(),),
plt.figure(2)
sns.boxplot(data=df,y='Age')
# from boxplot 75th%ile seems to b 38 n 25th percentile seems to be 20.....
#so multiplying by 1.5 at both ends so Age(10,57) seems good and any value outside this ...lets consider as outliers..
#also using this age for calaculating mean for replacing na values of age.
df=df.loc[df['Age'].between(9,58),]
# test=test.loc[test['Age'].between(9,58),]
# test=test.loc[test['Age'].between(9,58),]
df=df.reset_index(drop=True,)
class_3_age=df.loc[df['Pclass']==3].Age.mean()
class_2_age=df.loc[df['Pclass']==2].Age.mean()
class_1_age=df.loc[df['Pclass']==1].Age.mean()
def remove_null_age(data):
agee=data[0]
pclasss=data[1]
if pd.isnull(agee):
if pclasss==1:
return class_1_age
elif pclasss==2:
return class_2_age
else:
return class_3_age
return agee
df['Age']=df[["Age","Pclass"]].apply(remove_null_age,axis=1)
test['Age']=test[["Age","Pclass"]].apply(remove_null_age,axis=1)
sex=pd.get_dummies(df['Sex'],drop_first=True)
test_sex=pd.get_dummies(test['Sex'],drop_first=True)
sex=sex.reset_index(drop=True)
test_sex=test_sex.reset_index(drop=True)
df=df.drop(columns=['Sex'])
test=test.drop(columns=['Sex'])
df=pd.concat([df,sex],axis=1)
test=test.reset_index(drop=True)
df=df.reset_index(drop=True)
test=pd.concat([test,test_sex],axis=1)
survived_df=df["Survived"]
df=df.drop(columns='Survived')
test["Age"]=test['Age'].round(1)
test.at[152,'Fare']=30
from sklearn.linear_model import LogisticRegression
logreg=LogisticRegression()
logreg.fit(df,survived_df)
predictions=logreg.predict(test)
from sklearn.metrics import accuracy_score
accuracy=accuracy_score(test_survived,predictions)
print(accuracy)

Answer 1

You probably want to get the accuracy for the predictions together with the column Survived of the test_survived dataframe:
from sklearn.metrics import accuracy_score
accuracy=accuracy_score(test_survived['Survived'],predictions)
print(accuracy)
Your error occured, because the accuracy_score() only takes two 1-dimensional arrays, one as the ground truth labels and the other as the predicted labels. But you provided a 2-dimensional "array" (the dataframe) and the 1-dimensional predictions, hence it assumed that your first input is a multiclass-output.
The documentation is also very resourceful for this.