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Hello, I was trying to import data from an Excel file. After I imported the data, I was trying to make a scatter plot. The X axes variable is a time variable, which occupies two columns, one is date, another one is time. Example 21-Apr-03, 4:10 PM. My qestion is: 1. How can I access the data of certain column? I mean how can I refer it in R? 2. How can I make the two column character

How can I deal with missing values in the excel file? I used read.csv to imports data, how ever there are missing values in the csv file. When I use names(), it turns out a error message: " names attribute must be the same length as the vector" What can i do with the missing values? Thanks --------------------------------- [[alternative HTML version deleted]]

In R, How to read Excel file and access the data item? Thank you. --------------------------------- [[alternative HTML version deleted]]

if I want to specify y-coordinates for the heights of horizontal lines to go across a plot. x <- c(1,2,3,6,4,8,4,7) y <- c(3,2,7,4,5,4,5,6) h <- c(3,5,7) plot(x,y) abline(y=h) However I got error message: Warning message: parameter "y" couldn't be set in high-level plot() function (I tried abline(h=y) , it;s not what I want also) Do u know why?

ABCD are four matrix. A * Inverse((Transpose(A)*Tranpose(B)*B*A+C)) * Transpose(A) * Transpose(B) * D how to write in R in an efficient way? --------------------------------- [[alternative HTML version deleted]]