I have this dataframe "df1" as example which is actually part of a much larger one (15 years):
X1 X2
3798 2009-12-29 0
3799 2009-12-30 0
3800 2009-12-31 0
3802 2010-01-02 0
3803 2010-01-03 2.1
3804 2010-01-04 0
3805 2010-01-05 0
3806 2010-01-06 0
3807 2010-01-07 0
3808 2010-01-08 0
3809 2010-01-09 0
3810 2010-01-10 6.8
3811 2010-01-12 0
3812 2010-01-13 0
3813 2010-01-14 17.7
3814 2010-01-16 0
3815 2010-01-17 0
3816 2010-01-18 1.5
3817 2010-01-19 0
3818 2010-01-20 0
3819 2010-01-21 0
3820 2010-01-22 0
3821 2010-01-23 0
3822 2010-01-24 0
3823 2010-01-25 0
3824 2010-01-26 0
3825 2010-01-27 4.5
3826 2010-01-28 0
3827 2010-01-29 0
3828 2010-01-31 0
3829 2010-02-01 0
3830 2010-02-03 0
3831 2010-02-04 0
3832 2010-02-05 0
3833 2010-02-07 0
3834 2010-02-08 0
3835 2010-02-09 1.2
I want to use this dataframe to create a new one "df2" with averages per month. Does anyone know how to do this? Help would be great!
One way, using base
R would be to make sure your dates are of class Date
or similar ( e.g. POSIXct) if you haven't already, and then to extract the months and years (as your data spans more than one year) and aggregate like so:
# Convert to date if not already
df1$X1 <- as.Date(df1$X1)
# Get months
df1$Month <- months(df1$X1)
# Get years
df1$Year <- format(df1$X1,format="%y")
# Aggregate 'X2' on months and year and get mean
aggregate( X2 ~ Month + Year , df1 , mean )
# Month Year X2
#1 December 09 0.0000000
#2 February 10 0.1714286
#3 January 10 1.2074074
There are quite a few ways of doing this if you have a look around.