i need to create a query that finds the counties that belong to regions 1 or 2, whose name starts with 'Washington', and whose POPESTIMATE2015 was greater than their POPESTIMATE 2014 , using pandas This function should return a 5x2 DataFrame with the columns = ['STNAME', 'CTYNAME'] and the same index ID as the census_df (sorted ascending by index)
you'll find a description of my data in the picture : 
Consider the following demo:
In [19]: df
Out[19]:
REGION STNAME CTYNAME POPESTIMATE2014 POPESTIMATE2015
0 0 Washington Washington 10 12
1 1 Washington Washington County 11 13
2 2 Alabama Alabama County 13 15
3 4 Alaska Alaska 14 12
4 3 Montana Montana 10 11
5 2 Washington Washington 15 19
In [20]: qry = "REGION in [1,2] and POPESTIMATE2015 > POPESTIMATE2014 and CTYNAME.str.contains('^Washington')"
In [21]: df.query(qry, engine='python')[['STNAME', 'CTYNAME']]
Out[21]:
STNAME CTYNAME
1 Washington Washington County
5 Washington Washington
Use boolean indexing with mask created by isin and startswith:
mask = df['REGION'].isin([1,2]) &
df['COUNTY'].str.startswith('Washington') &
(df['POPESTIMATE2015'] > df['POPESTIMATE2014'])
df = df.loc[mask, ['STNAME', 'CTYNAME']]
