How to set values in dataframe to a value before every date in every year [duplicate]
I've got some daily data in a Pandas DataFrame and it has a nice index. Something like this:
import pandas as pd
import numpy as np
rng = pd.date_range('1/1/2010', periods=1000, freq='D')
ts = pd.DataFrame(randn(len(rng)), index=rng, columns=['vals'])
print ts.head()
vals
2010-01-01 1.098302
2010-01-02 -1.384821
2010-01-03 -0.426329
2010-01-04 -0.587967
2010-01-05 -0.853374
I'd like to subset my DataFrame to only the records that fall between February 2 & March 3 for all years.
It seems there should be a very Pandas-esque way of doing this but I'm struggling to find it. Any help?
I don't think there is a native way to do this (there is with between times).
But you can do it naively (this will be efficient, but is a pain to write!):
In [11]: ts[((ts.index.month == 2) & (2 <= ts.index.day) # in Feb after the 2nd inclusive
| (ts.index.month == 3) & (ts.index.day <= 3))] # in March before the 3rd inclusive
Out[11]:
<class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 94 entries, 2010-02-01 00:00:00 to 2012-03-03 00:00:00
Data columns (total 1 columns):
vals 94 non-null values
dtypes: float64(1)
To select all records of an annual returning period covering multiple months, do as follow:
rng = pd.date_range('2010-1-1', periods=1000, freq='D')
df = pd.DataFrame(np.random.randn(len(rng)), index=rng, columns=['A'])
startMM, startdd = (2,15) # Feb 15th
endMM, enddd = (10,3) # Oct 3rd
month_day = pd.concat([
df.index.to_series().dt.month,
df.index.to_series().dt.day
], axis=1).apply(tuple, axis=1)
df[(month_day >= (startMM, startdd)) & (month_day <= (endMM, enddd))]
as mentioned by @IanS in https://stackoverflow.com/a/45996897/2459096