lyashevska

import pandas as pd

d = {'dat': ['2016-01-01', '2016-01-02', '2016-01-03', '2017-01-01', '2017-01-02', '2017-01-03'],'x': [1, 2, 3, 4, 5, 6]}
df1 = pd.DataFrame(d)
df1.set_index(['dat'], inplace=True)
df1.index = pd.to_datetime(df1.index)

d = {'dat': ['2016-01-01', '2017-01-01'],'y': [10, 11]}
df2 = pd.DataFrame(d)
df2.set_index(['dat'], inplace=True)

lyashevska

# List unique values in a DataFrame column
pd.unique(df.column_name.ravel())

# Convert Series datatype to numeric, getting rid of any non-numeric values
df['col'] = df['col'].astype(str).convert_objects(convert_numeric=True)

# Grab DataFrame rows where column has certain values
valuelist = ['value1', 'value2', 'value3']
df = df[df.column.isin(valuelist)]