1 How could I generate a manifest file with filtering of Race and Ethnicity?

From https://support.bioconductor.org/p/9138939/.

library(GenomicDataCommons,quietly = TRUE)

I made a small change to the filtering expression approach based on changes to lazy evaluation best practices. There is now no need to include the ~ in the filter expression. So:

q = files() %>%
    cases.project.project_id == 'TCGA-COAD' &
      data_type == 'Aligned Reads' &
      experimental_strategy == 'RNA-Seq' &
      data_format == 'BAM')

And get a count of the results:

## [1] 1188

And the manifest.