尝试根据另一列上的值分配标签，但得到的值总是相同的

Question

我正在尝试根据另一列的值为一列指定一些标签。'Percentage_delay'列的值的范围从0到1。如果'Percentage_delay'列的值大于0.75，则'Labels'列上的相应值应为'high'，如果小于0.75且大于0.5'medium'，如果小于0.5'low'

我想出了这个密码：

for i in number_delay_aiport['Percentage_delay']:
    if i >= 0 and i < 0.25:
        number_delay_aiport['Labels'] = 'low'
    if i >= 0.25 and i < 0.75:
        number_delay_aiport['Labels'] = 'medium'
    if i >= 0.75 and i <= 1:
        number_delay_aiport['Labels'] = 'high'

输出错误，因为我只有Label == 'high'： Output

如果我使用'return'函数，也会发生同样的情况

你能告诉我为什么会这样吗

Answer 1

将for循环更改为枚举for循环，并在标签上使用iloc：

import pandas as pd

d = {"Percentage_delay" : [0.64, 0.80, 0.55, 0.48, 0.65, 0.46, 0.87, 0.66, 0.77, 0.44]}

number_delay_airport = pd.DataFrame(d)
# to use iloc you first have to create the column
number_delay_airport['Labels'] = ''
for j, i in enumerate(number_delay_airport['Percentage_delay']):
    print(i,j)
    if i >= 0 and i < 0.25:
        number_delay_airport['Labels'].iloc[j] = 'low'
    if i >= 0.25 and i < 0.75:
        number_delay_airport['Labels'].iloc[j] = 'medium'
    if i >= 0.75 and i <= 1:
        number_delay_airport['Labels'].iloc[j] = 'high'

print(number_delay_airport)

或者更好的方法是，使用apply函数可以执行以下操作：

import pandas as pd

d = {"Percentage_delay" : [0.64, 0.80, 0.55, 0.48, 0.65, 0.46, 0.87, 0.66, 0.77, 0.44]}

number_delay_airport = pd.DataFrame(d)

def assign_label(i):
    if i >= 0 and i < 0.25:
        return 'low'
    if i >= 0.25 and i < 0.75:
        return 'medium'
    if i >= 0.75 and i <= 1:
        return 'high'

number_delay_airport['Labels'] = number_delay_airport['Percentage_delay'].apply(assign_label)

print(number_delay_airport)