Question

为了在各个地区进行有意义的比较，我想在不同国家的爆发开始日期之前对COVID-19确诊病例进行标准化。对于任何领土，领土达到或超过10例确诊病例的那一天都被视为“爆发的第0天”。

示例数据框：

[in]
import pandas as pd
confirmed_cases = {'Date':['1/22/20', '1/23/20', '1/24/20', '1/25/20', '1/26/20'], 'Australia':[0, 0, 0, 30, 50], 'Albania':[0, 20, 25, 30, 50], 'Algeria':[25, 40, 50, 50, 70]}
df = pd.DataFrame(confirmed_cases)
df

[out]
    Date    Australia   Albania     Algeria
0   1/22/20        0         0          25
1   1/23/20        0        20          40
2   1/24/20        0        25          50
3   1/25/20       30        30          50
4   1/26/20       50        50          70

所需结果：

    Day Since Outbreak     Australia    Albania     Algeria
0           0                    30         20          25
1           1                    50         25          40
2           2                   NaN         30          50
3           3                   NaN         50          50
4           4                   NaN        NaN          70

有没有办法用简单的Python / Panda代码行来执行此任务？

Answer 1

为每个国家/地区找到超过阈值（10）的第一个值的索引值，然后将每一列向上移动那么多

df2 = df[['Australia', 'Albania', 'Algeria']].apply(lambda x: x.shift(-(x > 10).idxmax()))
# df2
   Australia  Albania  Algeria
0       30.0     20.0       25
1       50.0     25.0       40
2        NaN     30.0       50
3        NaN     50.0       50
4        NaN      NaN       70

重置索引以获取“天起”列

df2.reset_index().rename(columns={'index': 'Day Since Outbreak'})

   Day Since Outbreak  Australia  Albania  Algeria
0                   0       30.0     20.0       25
1                   1       50.0     25.0       40
2                   2        NaN     30.0       50
3                   3        NaN     50.0       50
4                   4        NaN      NaN       70

Answer 2

根据第一次运行的值<10，确定需要shift每列多少次，然后移动它们。 cummin确保如果间歇值<10，则不会计入shift

df = df.drop(columns='Date')  # Wont need
s = df.lt(10).cummin().sum()

for col, shift in s.iteritems():
    df[col] = df[col].shift(-shift)

df['Days Since'] = range(len(df)) # Duplicative with index...

   Australia  Albania  Algeria  Days Since
0       30.0     20.0       25           0
1       50.0     25.0       40           1
2        NaN     30.0       50           2
3        NaN     50.0       50           3
4        NaN      NaN       70           4

熊猫：如何针对爆发天数不同的不同国家/地区对COVID-19数据框进行标准化

2 个答案: