This question already has answers here:
How to get the mean of specific columns in dataframe and store in vector (in R)
(1 answer)
Find mean of multiple columns in R
(4 answers)
Closed 2 months ago.
I have a large dataset. I want to calculate the mean of some of the columns in the data set together. I am not sure how I can use the
colMeans ()
I have only found how to calculate for categories and rows.
Let me take embedded data iris in R as an example.
colMeans(iris[, 1:3], na.rm=TRUE) # select columns #1~3.
Related
This question already has answers here:
Normalizing selection of dataframe columns with dplyr
(2 answers)
Closed 3 years ago.
In need to normalise my data by dividing each value by the mean of the entire column, preferably using dplyr.
assume
inputs <- c(3,5,3,9,12)
mydata = data.frame(inputs)
I would like all the values replaced by themselves divided by the mean, which is 6.4.
Any straightforward suggestion?
We can use sapply in base R for generalized approach
sapply(mydata, function(x) x/mean(x))
Or with colMeans if more than one column
mydata/colMeans(mydata)[col(mydata)]
This question already has answers here:
Mean per group in a data.frame [duplicate]
(8 answers)
How to find mean for subset using R?
(2 answers)
Closed 3 years ago.
Beginner problem in R. I have a data frame in R that has 1 column ranking the data into specific subgroups, named "Group" (Groups: Heavy, Medium, Light), then another column with values (named "Value") of those groups. How do I check, for example the mean, within the "value" column for a specific subset based on the "Group" column, lets say for "Heavy"?
This question already has answers here:
calculate the mean for each column of a matrix in R
(10 answers)
Closed 4 years ago.
I'm new to R and still learning. I have a matrix with 100 columns and I need to calculate the average of each column and store all those values for further calculations. Each column has 5 numbers and after this step i'm supposed to have 100 new values. Also, please let me know if the replicate() function is a viable way to do this in just one line.
colMeans(DF)
Is a highly optimized function for exactly this purpose.
This question already has answers here:
How to count the number of unique values by group? [duplicate]
(1 answer)
Unique values in each of the columns of a data frame
(9 answers)
Closed 5 years ago.
Is there better way to compute this instead of:
length(unique(vector))
let's assume that we donno what class is the vector.
You can use
library(data.table)
vector <- c(1,2,2,2,3)
uniqueN(vector)
This question already has answers here:
How to find the highest value of a column in a data frame in R?
(10 answers)
Closed 7 years ago.
I have the following dataframe:
I would like to create a table of the column headers, in a column with their maximum value to the right of them. I will be looking to embed this in a Shiny App. Does anyone know how I can do this?
I used:
colMax <- function(data) sapply(data, max, na.rm=TRUE)
Then I called as.data.frame(colmax(data)) and it worked as needed.
Duplicate: How to find the highest value of a column in a data frame in R?