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.
Related
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.
This question already has answers here:
Counting the number of elements with the values of x in a vector
(20 answers)
Closed 1 year ago.
I have this data and I want to figure out a way to know how many ones and how many zeros are in each column (ie Arts and Crafts). I have been trying different things but it hasn't been working. Does anyone have any suggestions?
You can use the table() function in R. This creates a categorical representation of your data. Additionally here convert list to vector I have used unlist() function.
df1 <- read.csv("Your_CSV_file_name_here.csv")
table(unlist(df1$ArtsAndCrafts))
If you want to row vice categorize the number of zeros and ones you can refer to this question in Stackoverflow.
This question already has answers here:
Getting the last n elements of a vector. Is there a better way than using the length() function?
(6 answers)
Closed 5 years ago.
suppose I have daily time series data under variable name "prices", but im only interested in the past 100 days. How would i extract the last 100 elements from this variable?
Something equivalent to python's prices[-100:] but for R?
If it's a vector:
tail(prices, 100)
This question already has answers here:
How to get all possible combinations of n number of data set?
(2 answers)
How to calculate combination and permutation in R?
(6 answers)
Closed 5 years ago.
I am getting a tough time in selecting the combinations of factors.
I have a vector as ("Ryan", "Leo", "Jack","Harry","Edd").
I want to get the list of of all combinations taken 3 of the names once.
I want to do it in R. Probably a resultant matrix will help me.
We can use combn
t(combn(vec1, 3))
This question already has an answer here:
Vector of cumulative sums in R
(1 answer)
Closed 6 years ago.
I'm having real difficulty performing a calculation that is incredibly easy to perform in excel. What i require is a kind of rolling addition whereby the value in one column is added to preceding data point. For example:
column a: 1,2,3,5,16,18,3,11
would produce:
column b: 1,3,6,11,27,45,48,59
i.e. (1+1=2),(2+1=3),(3+3=6),(5+6=11)...
I have a feeling I'm missing something really obvious but have tried various iterations of rollapply and shift with no success... How can I do this in R? What am I missing?
The function you are looking for is cumsum:
df = data.frame(a=1:10)
df$b = cumsum(df$a)