PYTHON

between date pandas

df[df.some_date.between(start_date, end_date)]

pandas diff between dates

df[['A','B']] = df[['A','B']].apply(pd.to_datetime) #if conversion required
df['C'] = (df['B'] - df['A']).dt.days

datediff in seconds in pandas

t1 = pd.to_datetime('1/1/2015 01:00')
t2 = pd.to_datetime('1/1/2015 03:30')

print pd.Timedelta(t2 - t1).seconds / 3600.0

pandas difference between dates

# credit to Stack Overflow user in the source link
import pandas as pd 
# df is your pandas dataframe
# if already datetime64 you don't need to use to_datetime

df['A'] = pd.to_datetime(df['A'])
df['B'] = pd.to_datetime(df['B']) 

df['diff'] =  df['A'] - df['B'] # difference in days