Whatever TomDLT answered it may not work for some of you because
data1 = pd.DataFrame(data= np.c_[iris['data'], iris['target']],
columns= iris['feature_names'] + ['target'])
because iris['feature_names'] returns you a numpy array. In numpy array you can't add an array and a list ['target'] by just + operator. Hence you need to convert it into a list first and then add.
You can do
data1 = pd.DataFrame(data= np.c_[iris['data'], iris['target']],
columns= list(iris['feature_names']) + ['target'])
This will work fine tho..