I have a data frame with several columns; some numeric and some character. How to compute the sum of a specific column? I’ve googled for this and I see numerous functions (sum
, cumsum
, rowsum
, rowSums
, colSums
, aggregate
, apply
) but I can’t make sense of it all.
For example suppose I have a data frame people
with the following columns
people <- read(
text =
"Name Height Weight
Mary 65 110
John 70 200
Jane 64 115",
header = TRUE
)
…
How do I get the sum of all the weights?
This question is related to
r
dataframe
sum
aggregate-functions
to order after the colsum :
order(colSums(people),decreasing=TRUE)
if more than 20+ columns
order(colSums(people[,c(5:25)],decreasing=TRUE) ##in case of keeping the first 4 columns remaining.
To sum values in data.frame
you first need to extract them as a vector.
There are several way to do it:
# $ operatior
x <- people$Weight
x
# [1] 65 70 64
Or using [, ]
similar to matrix:
x <- people[, 'Weight']
x
# [1] 65 70 64
Once you have the vector you can use any vector-to-scalar function to aggregate the result:
sum(people[, 'Weight'])
# [1] 199
If you have NA values in your data, you should specify na.rm
parameter:
sum(people[, 'Weight'], na.rm = TRUE)
When you have 'NA' values in the column, then
sum(as.numeric(JuneData1$Account.Balance), na.rm = TRUE)
Source: Stackoverflow.com