英文:
How to apply pandas dataframe.where on just one column
问题
我正在尝试使用dataframe.where将一些天数添加到数据框列中，但它的行为很奇怪。以下是数据框、当前结果和预期结果。
my_dict={'NAME':['Ravi','Raju','Alex','Ron','King','Jack'],
'ID':[1,2,3,4,5,6],
'MATH':[80,40,70,70,82,30],
'ENGLISH':[81,70,40,50,60,30],
'Result Date': ['2021-08-01', '2021-04-24', '2021-09-30', '2021-07-13', '2021-09-30', '2021-07-13'],
}
my_data = pd.DataFrame(data=my_dict)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
my_data['Result Date'] = my_data.where(my_data["ID"] > 5, my_data['Result Date'] + pd.Timedelta(days=14), axis=1)
当前结果：
预期结果：
英文:
I'm trying to add some days to a dataframe column using dataframe.where, but it behaves weirdly. Here is the dataframe, current result and expected result.
my_dict={'NAME':['Ravi','Raju','Alex','Ron','King','Jack'],
'ID':[1,2,3,4,5,6],
'MATH':[80,40,70,70,82,30],
'ENGLISH':[81,70,40,50,60,30],
'Result Date': ['2021-08-01', '2021-04-24', '2021-09-30', '2021-07-13', '2021-09-30', '2021-07-13'],
}
my_data = pd.DataFrame(data=my_dict)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
my_data['Result Date'] = my_data.where(my_data["ID"] > 5, my_data['Result Date'] + pd.Timedelta(days=14), axis=1)
Current result:
Expected result:
答案1
得分: 1
在my_dict中假设您输入了到达时间的拼写错误，因为您没有提及到达时间。
以下是更新后的代码：
import pandas as pd
import numpy as np
my_dict = {'NAME': ['Ravi', 'Raju', 'Alex', 'Ron', 'King', 'Jack'],
'ID': [1, 2, 3, 4, 5, 6],
'MATH': [80, 40, 70, 70, 82, 30],
'ENGLISH': [81, 70, 40, 50, 60, 30],
'Result Date': ['2021-08-01', '2021-04-24', '2021-09-30', '2021-07-13', '2021-09-30', '2021-07-13']}
my_data = pd.DataFrame(data=my_dict)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
my_data['Result Date'] = np.where(my_data["ID"] > 5, my_data['Result Date'] + pd.Timedelta(days=14), None)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
print(my_data)
输出：
NAME ID MATH ENGLISH Result Date
0 Ravi 1 80 81 NaT
1 Raju 2 40 70 NaT
2 Alex 3 70 40 NaT
3 Ron 4 70 50 NaT
4 King 5 82 60 NaT
5 Jack 6 30 30 2021-07-27
英文:
assuming you had a typo error with Arrival time as you haven't mentioned anything about Arrival time in the my_dict
here is the updated code
import pandas as pd
import numpy as np
my_dict={'NAME':['Ravi','Raju','Alex','Ron','King','Jack'],
'ID':[1,2,3,4,5,6],
'MATH':[80,40,70,70,82,30],
'ENGLISH':[81,70,40,50,60,30],
'Result Date': ['2021-08-01', '2021-04-24', '2021-09-30', '2021-07-13', '2021-09-30', '2021-07-13'],
}
my_data = pd.DataFrame(data=my_dict)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
my_data['Result Date'] = np.where(my_data["ID"] > 5, my_data['Result Date'] + pd.Timedelta(days=14), None)
my_data['Result Date'] = pd.to_datetime(my_data['Result Date'])
print(my_data)
output:
NAME ID MATH ENGLISH Result Date
0 Ravi 1 80 81 NaT
1 Raju 2 40 70 NaT
2 Alex 3 70 40 NaT
3 Ron 4 70 50 NaT
4 King 5 82 60 NaT
5 Jack 6 30 30 2021-07-27
答案2
得分: 0
下面的代码可以获取所需的结果。Yashaswi K的答案有效，但我们需要使用另一个库Numpy，但我正在寻找使用Pandas的解决方案。
my_data['Result Date'] = (my_data['Result Date'] + pd.Timedelta(days=14)).where(my_data["ID"] > 5, None)
英文:
The code below works to get the desired result. The answer by Yashaswi K works, but we need to use another library, Numpy, but I was looking for something using Pandas.
my_data['Result Date'] = (my_data['Result Date'] + pd.Timedelta(days=14)).where(my_data["ID"] > 5, None )
答案3
得分: 0
使用where在特定列上：
my_data['Result Date'] = my_data['Result Date'].where(my_data["ID"] > 5) + pd.Timedelta(days=14)
英文:
Use where on the specific column:
my_data['Result Date'] = my_data['Result Date'].where(my_data["ID"].gt(5))+pd.Timedelta(days=14)
>>> my_data
NAME ID MATH ENGLISH Result Date
0 Ravi 1 80 81 NaT
1 Raju 2 40 70 NaT
2 Alex 3 70 40 NaT
3 Ron 4 70 50 NaT
4 King 5 82 60 NaT
5 Jack 6 30 30 2021-07-27
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