Dr. Feng Li

Category: Default

  • Add comments on your R objects

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    by

    Feng Li
    in ,

    It is always good to add comments on your R code. But it is also good to add comments on your objects like variables, functions, etc. > Mydata comment(Mydata) <- “This is a data from a sequence” > Mydata [1] 1 2 3 4 5 6 7 8 9 10 > comment(Mydata) [1] “This is…

  • Set fonts size in R plot

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    by

    Feng Li
    in ,

    You probably have discovered that R usually gives you different size of fonts in different figures. That is because a numerical value (cex in par function) giving the amount by which plotting text and symbols is magnified relative to a default value. This starts as ‘1’ when a device is opened, and is reset when…

  • A fast routine of making a commutation matrix

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    by

    Feng Li
    in ,

    R does not have this function by default, so I wrote a faster routine K() to create a commutation matrix.We always use the notation of commutation matrix on the paper. But when we put it into practice, we typically need the result of a dense matrix by pre- or post-multiplied by a commutation matrix. i.e.,…