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R: calculating average row value based on partial column match

I have a table that looks like this:

er er.1 as as.1 as.2 rt op a 1 6 90 8 6 4 87 b 1 8 56 7 5 5 9 c 8 7 6 4 5 9 6 d 1 0 8 6 4 3 6 e 9 7 2 4 3 89 7

I would like to calculate the average value of a row between columns with partially matching names to get this result:

  er as rt op a 3.5 34.66666667 4 87 b 4.5 22.66666667 5 9 c 7.5 5 9 6 d 0.5 6 3 6 e 8 3 89 7

I found some helpful tips on this:

Calculate row value based on (partial) column name match

but it doesn't seem to work for me. Here are the commands I used:

 test <- read.table("test.txt", header=TRUE, row.names=1) colnames <- c("er", "er", "as", "as", "as", "rt", "op") means <-sapply(colnames, function(x) rowMeans(test [, grep(x, names(test))] ) )

This last command gives me the following error:

 Error in rowMeans(test[, grep(x, names(test))]) : 'x' must be an array of at least two dimensions

Here is the scope of my data frame:

 structure(list(er = c(1L, 1L, 8L, 1L, 9L), er.1 = c(6L, 8L, 7L, 0L, 7L), as = c(90L, 56L, 6L, 8L, 2L), as.1 = c(8L, 7L, 4L, 6L, 4L), as.2 = c(6L, 5L, 5L, 4L, 3L), rt = c(4L, 5L, 9L, 3L, 89L ), op = c(87L, 9L, 6L, 6L, 7L)), .Names = c("er", "er.1", "as", "as.1", "as.2", "rt", "op"), class = "data.frame", row.names = c("a", "b", "c", "d", "e"))

Any idea why I am getting this error and how can I fix it?

Thanks!

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1 answer

We can split and get rowMeans

 sapply(split.default(df1, sub("\\..*", "", names(df1))), rowMeans) # as er op rt #a 34.66667 3.5 87 4 #b 22.66667 4.5 9 5 #c 5.00000 7.5 6 9 #d 6.00000 0.5 6 3 #e 3.00000 8.0 7 89
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Source: https://habr.com/ru/post/1258764/

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