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rstandard-deviation

How to calculate standard deviation per row?

I am trying to calculate a standard deviation per row

The example of the input (values_for_all):

1  0.35 0.35 4.33 0.09 4.17 0.16 9.90 15.25 0.16 2.38 2.55 8.14 0.16 NA 0.16
2  8.75 3.22 7.34 0.56 2.43 0.23 1.20 8.45 1.26 NA NA 1.24 0.16 2.34 0.36

Code:

values_for_all[values_for_all == ''] <- NA
values_for_all[] <- lapply(values_for_all, as.numeric)
values_mean <- rowMeans(values_for_all, na.rm=TRUE) 

#calculating standard deviation per row 
SD <- rowSds(values_for_all, na.rm=TRUE)
SD

The first part (values_mean) works perfectly. Unfortunately, the part with SD doesn't.

Solution

  • apply lets you apply a function to all rows of your data:

    apply(values_for_all, 1, sd, na.rm = TRUE)

    To compute the standard deviation for each column instead, replace the 1 by 2.