How to sum up observations in a column in R?

Question

I have a df1:

Number State
42     AK
65     AK
31     TN
34     TN
12     MO
3      AK
41     MO
53     TN
23     AK

I would like to sum up the observations of State:

To see:

State Obs
AK    4
TN    3
MO    2

RaV · Answer 1 · 2020-04-03T18:12:19.367

1

You can use dplyr package:

library(dplyr)

df1 %>%
#grouping rows by State
  group_by(State) %>%
#using 'n()' to count number of observations for each State
  summarize(Obs = n())

Summarize() function will keep only grouped variable State and summarization variable Obs.

data:

df1 <- data.frame(Number = c(42, 65, 31, 34, 12, 3, 41, 53, 23),
                  State = c("AK", "AK", "TN", "TN", "MO", "AK", "MO", "TN", "AK"))

edited Apr 03 '20 at 18:12

answered Apr 03 '20 at 18:06

RaV

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1

Or `df1 %>% count(State)` – IceCreamToucan Apr 03 '20 at 18:15
1

@IceCreamToucan, that is much simpler solution, thank you. However, it is not enough if counting variable has to be named _Obs_ for some reason. – RaV Apr 03 '20 at 18:22

How to sum up observations in a column in R?

1 Answers1