CODEWITHSUNDEEP
rdataframe
LucasSeveryn
LucasSeveryn

Reputation: 6262

Taking average of dataframe elements sharing same date

I am a bit lost in how to take average of a data frame formatted in the following way:

id  date        quantity    product
1   12-05-2015  10          apple
2   21-03-2015  12          orange
3   12-05-2015  15          orange
4   21-03-2015  16          apple

Expected result:

date       quantity
21-03-2015 14
12-05-2015 12.5

I tried converting it to zoo object, but then I run into issues as dates are non-unique.

Upvotes: 2

Views: 56

Answers (2)

akrun
akrun

Reputation: 887068

Try

aggregate(quantity~date, df1, mean)
#        date quantity
#1 12-05-2015     12.5
#2 21-03-2015     14.0

Or

library(data.table)
setDT(df1)[, list(quantity=mean(quantity)), date]

As @Alex A. mentioned in the comments, list( can be replaced by .( in the recent data.table versions.

Upvotes: 5

Alex A.
Alex A.

Reputation: 5586

You could also use the dplyr package. Assuming your data frame is called df:

library(dplyr)

df %>%
    group_by(date) %>%
    summarize(quantity = mean(quantity))

#         date quantity
# 1 12-05-2015     12.5
# 2 21-03-2015     14.0

This gets the mean quantity grouped by date.

Upvotes: 3

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