Filter data.frame rows by a logical condition

Question

I want to filter rows from a data.frame based on a logical condition. Let\'s suppose that I have data frame like

   expr_value     cell_type
1           


        

Answer 1

I was working on a dataframe and having no luck with the provided answers, it always returned 0 rows, so I found and used grepl:

df = df[grepl("downlink",df$Transmit.direction),]

Which basically trimmed my dataframe to only the rows that contained "downlink" in the Transmit direction column. P.S. If anyone can guess as to why I'm not seeing the expected behavior, please leave a comment.

Specifically to the original question:

expr[grepl("hesc",expr$cell_type),]

expr[grepl("bj fibroblast|hesc",expr$cell_type),]