Python using "if" in Datetime Index

user_3239756 0
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I have a pd like below:

"Date" is the index, not column

Date Value
2020-01-01 1
2020-01-02 2
2020-01-03 3
2020-01-04 4
2020-01-05 5

and I want to do something like if date > 2020-01-02 and date < 2020-01-05

then Value = 0

Date Value
2020-01-01 1
2020-01-02 2
2020-01-03 0
2020-01-04 0
2020-01-05 5

.loc can only trim the whole data set and I don't want that. May I know what can I do to achieve this? Thanks

python-datetime python
2 Answers

In case it could be useful, here's an option using df.loc:

df['Date'] = pd.to_datetime(df['Date'])
df['Value'].loc[(df['Date'] > "2020-01-02") & (df['Date'] < "2020-01-05")] = 0
user_136958890

If you want if...else Try this:

import pandas as pd

df = pd.DataFrame({
    'Date': ['2020-01-01', '2020-01-02', '2020-01-03', '2020-01-04', '2020-01-05'],
    'Value': [1,2,3,4,5]})

df['Value'] = [
    0 if (x > '2020-01-02') & (x <= '2020-01-04') else  df['Value'].iloc[idx]
    for idx, x in enumerate(df['Date'])
]
print(df)

Output:

         Date    Value
0  2020-01-01      1
1  2020-01-02      2
2  2020-01-03      0
3  2020-01-04      0
4  2020-01-05      5

Or you can use .loc like below:

import pandas as pd

df = pd.DataFrame({
    'Date': ['2020-01-01', '2020-01-02', '2020-01-03', '2020-01-04', '2020-01-05'],
    'Value': [1,2,3,4,5]})

df['Date'] = pd.to_datetime(df['Date'])  
df.loc[(df['Date'] > '2020-01-02') & (df['Date'] <= '2020-01-04'), 'Value'] = 0

Edit Base On Your Comment (if Date is index):

import pandas as pd

df = pd.DataFrame({
    'Date': ['2020-01-01', '2020-01-02', '2020-01-03', '2020-01-04', '2020-01-05'],
    'Value': [1,2,3,4,5]})

df.set_index('Date', inplace=True)
df

Output:

enter image description here

For the above DataFrame you can use df.reset_index() and like below:

df = df.reset_index()
df['Date'] = pd.to_datetime(df['Date'])  
df.loc[(df['Date'] > '2020-01-02') & (df['Date'] <= '2020-01-04'), 'Value'] = 0

With if...else:

df = df.reset_index()
df['Value'] = [
    0 if (x > '2020-01-02') & (x <= '2020-01-04') else  df['Value'].iloc[idx]
    for idx, x in enumerate(df['Date'])
]
user_17405770
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