Find the average of a given set of numbers where the length of the set varies

Question

I want to find the average of given sets of numbers of varying length in R.

The data I have looks like this:

    company_name  marketcap  date
    A             100023     01-01-2000
    A             100234     02-01-2000
    A             108332     03-01-2000
    A
    .
    .
    A             112334     31-12-2000
    B              24342     01-01-2000
    B              25345     02-01-2000
.
.

There are hundred such companies. I want to calculate average value of marketcap for each company.

Output should look something like this (each marketcap value is an average rather than a set of numbers)

    company_name   marketcap  
    A              1023452   
    B               243425
.
.

akrun · Accepted Answer · 2019-05-07T10:27:03.710

2

We can use aggregate from base R to get the mean of 'marketcap' grouped by 'company_name'

aggregate(marketcap ~ company_name, df1, FUN = mean)

edited May 07 '19 at 10:27

answered May 07 '19 at 10:06

akrun

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get the Error in aggregate.data.frame(., company_name ~ nse_market_cap, FUN = mean) : 'by' must be a list – sylvestermarx May 07 '19 at 10:26
1

@sylvestermarx sorry , a typo. I forgot the dataset object identifier `df1`, Updated the code – akrun May 07 '19 at 10:27
1

thanks akrun!!! I got required result. – sylvestermarx May 07 '19 at 10:30

Newl · Answer 2 · 2019-05-07T11:54:23.677

2

Or you can use the aggregation/group-by of the data.table library as:

library(data.table)

dt <- as.data.table(your_data_frame)
dt[, .(marketcap = mean(marketcap)), by = company_name)]

edited May 07 '19 at 11:54

answered May 07 '19 at 10:42

Newl

310
2
12

Find the average of a given set of numbers where the length of the set varies

2 Answers2