熊猫pythongroupby取决于其他列表
我有 x 和 y 辆汽车，并想添加一个带有汽车块 (1-3) 的新列。“y_block_number_ends”给出了块结束的 y 坐标。
import pandas as pd
x_start = 1
y_start = 1
size_city = 5
y_block_number_ends = [2,4]
cars = pd.DataFrame({'x': np.repeat(np.arange(x_start,x_start+size_city),size_city),
'y': np.tile(np.arange(y_start,y_start+size_city),size_city)})
#cars['block_y']= cars.where([cars['y'] > 0 | (cars['y'] <= 2)])
print(cars)
新的数据框看起来像这样
x y block
0 1 1 1
1 1 2 1
2 1 3 2
3 1 4 2
4 1 5 3
5 2 1 1
6 2 2 1
7 2 3 2
8 2 4 2
9 2 5 3
10 3 1 1
11 3 2 1
12 3 3 2
13 3 4 2
14 3 5 3
15 4 1 1
16 4 2 1
17 4 3 2
18 4 4 2
19 4 5 3
20 5 1 1
21 5 2 1
22 5 3 2
23 5 4 2
24 5 5 3
回答
pd.cut
cars.assign(block=pd.cut(cars.y, [0, 2, 4, float('inf')], labels=[1, 2, 3]))
x y block
0 1 1 1
1 1 2 1
2 1 3 2
3 1 4 2
4 1 5 3
5 2 1 1
6 2 2 1
7 2 3 2
8 2 4 2
9 2 5 3
10 3 1 1
11 3 2 1
12 3 3 2
13 3 4 2
14 3 5 3
15 4 1 1
16 4 2 1
17 4 3 2
18 4 4 2
19 4 5 3
20 5 1 1
21 5 2 1
22 5 3 2
23 5 4 2
24 5 5 3
searchsorted
ends = np.array([2, 4])
labels = np.array([1, 2, 3])
cars.assign(block=labels[ends.searchsorted(cars.y)])
x y block
0 1 1 1
1 1 2 1
2 1 3 2
3 1 4 2
4 1 5 3
5 2 1 1
6 2 2 1
7 2 3 2
8 2 4 2
9 2 5 3
10 3 1 1
11 3 2 1
12 3 3 2
13 3 4 2
14 3 5 3
15 4 1 1
16 4 2 1
17 4 3 2
18 4 4 2
19 4 5 3
20 5 1 1
21 5 2 1
22 5 3 2
23 5 4 2
24 5 5 3