Pandas で特定の列が所定の条件を満たすすべての行のインデックスを取得する方法

import pandas as pd
import numpy as np

dates=['April-10', 'April-11', 'April-12', 'April-13','April-14','April-16']
sales=[200,300,400,200,300,300]
prices=[3, 1, 2, 4,3,2]

df = pd.DataFrame({'Date':dates ,
                   'Sales':sales ,
                   'Price': prices})

reqd_Index = df[df['Sales']>=300].index.tolist()
print(reqd_Index)

[1, 2, 4, 5]

import pandas as pd
import numpy as np

dates=['April-10', 'April-11', 'April-12', 'April-13','April-14','April-16']
sales=[200,300,400,200,300,300]
prices=[3, 1, 2, 4,3,2]

df = pd.DataFrame({'Date':dates ,
                   'Sales':sales ,
                   'Price': prices})

reqd_Index = list(np.where(df["Sales"] >= 300))
print(reqd_Index)

[array([1, 2, 4, 5])]

import pandas as pd
import numpy as np

dates=['April-10', 'April-11', 'April-12', 'April-13','April-14','April-16']
sales=[200,300,400,200,300,300]
prices=[3, 1, 2, 4,3,2]

df = pd.DataFrame({'Date':dates ,
                   'Sales':sales ,
                   'Price': prices})

reqd_index = df.query('Sales == 300').index.tolist()
print(reqd_index)

[1, 4, 5]