Python 格式和 Pandas

Question

我想使用 format 删除一些列。(想要删除列:new_cost0、new_0_quantity、new_2_cost 和 new_2_quantity)但并不是每一列都被删除。下面是数据框和代码。

数据框

    |new_0_cost|new_0_quantity|new_2_cost|new_2_quantity|quality|weights|     
   0| 10       | 20           |  10      | 20           | good  | 40    |

函数

def drop_cost_and_quan(data):
    # data is a dataframe described above
    # try to drop new_cost0, new_0_quantity, new_2_cost, and new_2_quantity
    data3 = data.copy()
    for i, item in enumerate(data3.columns):
        if item == 'new_{0}_cost'.format(i):
            data3 = data3.drop(item, axis=1)
        print('cost:',item == 'new_{0}_cost'.format(i))

    for i, item in enumerate(data3.columns):
        if item == 'new_{0}_quantity'.format(i):
            data3 = data3.drop(item, axis=1)
        print(item == 'item_{0}_quantity'.format(i))

    return data3

输出:

data3 = drop_cost_and_quan(data):

cost: True
cost: False
cost: True
cost: False
cost: False
cost: False
quntity: True
quntity: False
quntity: False
quntity: False

data3 
 |new_2_quantity|quality| weights|
0| 20           |good   |40

Answer 1

除了@vinod 的方法，你也可以这样做:

In [148]: df
Out[148]:
   new_0_cost  new_0_quantity  new_2_cost  new_2_quantity  new_0_total_cost  new_2_total_cost quality  weights
0          10              20          10              20              1111              2222    good       40

In [151]: df.drop(df.columns[df.columns.str.contains(r'^new_\d+_(?:quantity|cost)')], 1, inplace=True)

In [152]: df
Out[152]:
   new_0_total_cost  new_2_total_cost quality  weights
0              1111              2222    good       40

解释:

In [148]: df
Out[148]:
   new_0_cost  new_0_quantity  new_2_cost  new_2_quantity  new_0_total_cost  new_2_total_cost quality  weights
0          10              20          10              20              1111              2222    good       40

In [149]: df.columns.str.contains(r'^new_\d+_(?:quantity|cost)')
Out[149]: array([ True,  True,  True,  True, False, False, False, False], dtype=bool)

In [150]: df.columns[df.columns.str.contains(r'^new_\d+_(?:quantity|cost)')]
Out[150]: Index(['new_0_cost', 'new_0_quantity', 'new_2_cost', 'new_2_quantity'], dtype='object')