Great ! Does the job very well. Thank you.
I have a data frame in which the first column contains unique identifiers in the form of Arabidopsis AGI transcript numbers.
target_id est_counts tpm
AT1G01010.1 236 26.3
AT1G01020.2 55.0 12.2
AT1G01020.6 0 0
AT1G01020.1 25.2 4.8
AT1G01020.4 5.8 0.2
AT1G01020.5 45.5 8.8
AT1G01020.3 3.5 0.5
AT1G01030.2 13.25 1.3
AT1G01030.1 17.75 1.7
This table has data for three genes; AT1G01010, AT1G01020 and AT1G01030. However, two genes, AT1G01020 and AT1G01030 have multiple transcripts as indicated by the number to the right of the decimal. I would like to collapse the above table into three entries, one entry for each gene in which each column will contain the total for all transcripts of that gene. So, the resulting data frame will look like this:
target_id est_counts tpm
AT1G01010 236 26.3
AT1G01020 135.0 26.5
AT1G01030 31 3.0
Here, the values for est_counts and tpm for all transcripts of a single gene have been summed. I have seen things like lapply(.sd), but I don't think that will work because the AGI numbers are not exactly equal and my real table has thousands of different AGI numbers.
2 answers
Clean up target_id column, then aggregate other multiple columns at once, see:
# reproducible data
df1 <- read.table(text = "target_id est_counts tpm
AT1G01010.1 236 26.3
AT1G01020.2 55.0 12.2
AT1G01020.6 0 0
AT1G01020.1 25.2 4.8
AT1G01020.4 5.8 0.2
AT1G01020.5 45.5 8.8
AT1G01020.3 3.5 0.5
AT1G01030.2 13.25 1.3
AT1G01030.1 17.75 1.7", header = TRUE, stringsAsFactors = FALSE)
# we can imagine they are filenames and drop "extensions":
df1$target_id_clean <- tools::file_path_sans_ext(df1$target_id)
# then aggregate and sum on multiple columns
aggregate(.~target_id_clean, df1[-1], sum)
# target_id_clean est_counts tpm
# 1 AT1G01010 236 26.3
# 2 AT1G01020 135 26.5
# 3 AT1G01030 31 3.0
Assume your data us called data1, use aggregate():
## remove everything after the "."
data1$target_id <- sapply(strsplit(data1$target_id, split="\\."), function(x)x[1])
## sum using the aggregate() function, which reads as:
## sum up est_counts (or tpm) as a function of duplicated target_id entries:
results <- data.frame(aggregate(est_counts ~ target_id, data1, sum),
aggregate(tpm ~ target_id, data1, sum)[,2])
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