dataset = pd.read_csv("dataset.csv").fillna(" ")[:100]
dataset['Id']=0
dataset['i']=0
dataset['j']=0
#...
entries=dataset[dataset['Id']==0]
print type(entries)  # Prints <class 'pandas.core.frame.DataFrame'>
entries=entries.sort_values(['i','j','ColumnA','ColumnB'])

AttributeError: 'DataFrame' object has no attribute 'sort_values'

entries=entries.sort(['i','j','ColumnA','ColumnB'])