Rather than removing duplicates during the pivot table process, use the df.drop_duplicates() function to selectively drop duplicates.

For example if you are pivoting using these index='c0' and columns='c1' then this simple step yields the correct counts.

In this example the 5th row is a duplicate of the 4th (ignoring the non-pivoted c2 column

import pandas as pd
data = {'c0':[0,1,0,1,1], 'c1':[0,0,1,1,1], 'person':[0,0,1,1,1], 'c_other':[1,2,3,4,5]}
df = pd.DataFrame(data)
df2 = df.drop_duplicates(subset=['c0','c1','person'])
pd.pivot_table(df2, index='c0',columns='c1',values='person', aggfunc='count')

This correctly outputs

c1  0  1
c0      
0   1  1
1   1  1

It's an issue with how you're calling the data and if it's actually there.

train.loc[:,['Survived','Sex']]

tells me that there's a DataFrame (which is from pandas, hence the error) called train and this line is trying to access parts of that dataframe (it's just a type of an array). Specifically, it's trying to access columns named Survived and Sex.

Similarly, this line tells me there's another dataframe (df) known as test with a column named Sex and this is access that data.

test.loc[:,['Sex']]

The error code also informs me of some things

predictions = pandas.DataFrame({'PassengerId': test.PassengerId,'Survived': hypothesis.Survived.tolist()})

There's another df called predictions that's of dict type which is trying to access information from the another hypothesis df. The attribute it's tryin to access in the second key of the dict is

hypothesis.Survived.tolist()

which is a way of calling a column from that df. That is, when the predictions line is executed, it's trying to pull all the values from the Survived column of the hypothesis df.

The error is that the df doesn't actually have a column named Survived. So either there's missing data, or you're calling it wrong, or there's a missing reference.

Without knowing more about your code and your question, I can't really extrapolate much more.

The Iris Dataset from Sklearn is in Sklearn's Bunch format:

print(type(iris))
print(iris.keys())

output:

<class 'sklearn.utils.Bunch'>
dict_keys(['data', 'target', 'target_names', 'DESCR', 'feature_names', 'filename'])

So, that's why you can access it as:

x=iris.data
y=iris.target

But when you read the CSV file as DataFrame as mentioned by you:

iris = pd.read_csv('iris.csv',header=None).iloc[:,2:4]
iris.head()

output is:

    2   3
0   petal_length    petal_width
1   1.4 0.2
2   1.4 0.2
3   1.3 0.2
4   1.5 0.2

Here the column names are '1' and '2'.

First of all you should read the CSV file as:

df = pd.read_csv('iris.csv')

you should not include header=None as your csv file includes the column names i.e. the headers.

So, now what you can do is something like this:

X = df.iloc[:, [2, 3]] # Will give you columns 2 and 3 i.e 'petal_length' and 'petal_width'
y = df.iloc[:, 4] # Label column i.e 'species'

or if you want to use the column names then:

X = df[['petal_length', 'petal_width']]
y = df.iloc['species']

Also, if you want to convert labels from string to numerical format use sklearn LabelEncoder

from sklearn import preprocessing
le = preprocessing.LabelEncoder()
y = le.fit_transform(y)

make sure you write your line code true Example:

True way:

    `datafram.groupby('column')['column'].nunique()` #this is true way

wrong way:

    `datafram.groupby('column'),['column'].nunique()` #this way give you your error