S Ringne S Ringne - 4 days ago 6
Python Question

create a new dataframe from selecting specific rows from existing dataframe python

i have a table in my pandas dataframe. df

id count price
1 2 100
2 7 25
3 3 720
4 7 221
5 8 212
6 2 200


i want to create a new dataframe(df2) from this, selecting rows where count is 2 and price is 100,and count is 7 and price is 221

my output should be df2 =

id count price
1 2 100
4 7 221


i am trying using
df[df['count'] == '2' & df['price'] == '100']


but getting error

TypeError: cannot compare a dtyped [object] array with a scalar of type [bool]

Answer

You nedd add () because & has higher precedence than ==:

df3 = df[(df['count'] == '2') & (df['price'] == '100')]
print (df3)
  id count price
0  1     2   100

If need check multiple values use isin:

df4 = df[(df['count'].isin(['2','7'])) & (df['price'].isin(['100', '221']))]
print (df4)
  id count price
0  1     2   100
3  4     7   221

But if check numeric, use:

df3 = df[(df['count'] == 2) & (df['price'] == 100)]
print (df3)

df4 = df[(df['count'].isin([2,7])) & (df['price'].isin([100, 221]))]
print (df4)
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