Find median of every row using matrixStats::rowMedians

Question

I am trying to calculate the row median for a data frame df with rowMedians from matrixStats package.

Abundance Sample         


        

Answer 1

I think you need to remove first column because it's not numeric :

df$median_score <- apply(df[,-1], 1, median)

Answer 2

You don't want to include that Abundance column for median calculation. Let df be your current data frame.

library(matrixStats)
rowMedians(as.matrix(df[-1]))

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A few comments besides the correct code above.

1. Have you checked what matrix(df) is?
2. Even if it correctly returns you a numeric matrix, it does not overwrite df. So rowMedians(df) gives you the same error as if nothing has happened;
3. As an exercise, compare as.matrix(df[-1]) and as.matrix(df).

Understanding these issues prevents you from getting errors in future.