CODEWITHSUNDEEP
pythonpandasdatetime
WJA
WJA

Reputation: 7004

Previous month datetime pandas

I have a datetime instance declared as follows:

dtDate = datetime.datetime(2016,1,1,0,0)

How do I get the previous month and previous year from dtDate?

e.g. something like:

dtDate.minusOneMonth()
# to return datetime.datetime(2015,12,1,0,0)

Upvotes: 11

Views: 20147

Answers (4)

kevin_theinfinityfund
kevin_theinfinityfund

Reputation: 2187

To Manipulate an entire pandas series.

Use pd.DateOffset() with .dt.to_period("M")

df['year_month'] = df['timestamp'].dt.to_period("M")
df['prev_year_month'] = (df['timestamp'] - pd.DateOffset(months=1)).dt.to_period("M")

enter image description here

If you want to go forward a month, set months=-1.

Upvotes: 3

jezrael
jezrael

Reputation: 863701

You can use:

dtDate = datetime.datetime(2016,1,1,0,0)

print (dtDate - pd.DateOffset(months=1))
2015-12-01 00:00:00

print (dtDate - pd.DateOffset(years=1))
2015-01-01 00:00:00

Add s is important, because if use year only:

print (dtDate - pd.DateOffset(year=1))
0001-01-01 00:00:00

Upvotes: 20

Serenity
Serenity

Reputation: 36715

Use relativedelta from dateutil:

import datetime
import dateutil.relativedelta
dtDate = datetime.datetime(2016,1,1,0,0)
# get previous month
print ((dtDate+dateutil.relativedelta.relativedelta(months=-1)).month)
# get previous year
print ((dtDate+dateutil.relativedelta.relativedelta(years=-1)).year)

Output: 

12
2015

Upvotes: 1

EdChum
EdChum

Reputation: 394459

You can use DateOffset:

In [32]:    
dtDate = dt.datetime(2016,1,1,0,0)
dtDate - pd.DateOffset(months=1)

Out[32]:
Timestamp('2015-12-01 00:00:00')

Upvotes: 3

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