熊猫numpy累积余额

Question

import pandas as pd
data = {
    'Date': ['2020-01-01', '2020-01-02', '2020-01-03', '2020-01-04',
             '2020-02-01', '2020-02-08', '2020-02-15', '2020-02-22',
             '2020-02-29','2020-03-07','2020-03-15','2020-03-22'],

    'stock': [5, 0, 0, 0
              , 0, 0, 0, 0
              , 0, 0, 0, 0],
    'in': [14, 4, 29, 2
           , 0, 0, 0, 0
           , 0, 0, 0, 0],
    'out': [-10, -25, -8,-8
            , -8, -8, -8, -8
            , -8, -8, -8, -8],
'supplier': [0, 0, 0,0
            , 0, 0, 0, 0
            , 0, 0, 0, 0]
    }

df1 = pd.DataFrame ( data, columns=['Date',  'stock', 'in', 'out','supplier'] )
df1['Sum_Stock'] = df1['stock'] + df1['in'] + df1['out']+df1['supplier']
df1['cum_Stock'] = df1['Sum_Stock'].cumsum ( axis=0 )
print ( df1 )

如何更新“供应商”列并使每行的['cum_Stock']大于0。

如果['cum_Stock']大于0，则“供应商”为0。

“供应商”不能为负，但应最小化。

谢谢！