In R : select a value in a column by the corresponding row argument-CodePudding

how can I select and extract a biomass value based on the name of the corresponding fish ?

fish_data <- data.frame(names = c("Fish_1", "Fish_2", "Fish_3", "Fish_4", "Fish_5"), 
                            biomass = c(1.532, 2.243, 1.325, 1.098, 4.347))

##################

   names biomass
1 Fish_1   1.532
2 Fish_2   2.243
3 Fish_3   1.325
4 Fish_4   1.098
5 Fish_5   4.347

CodePudding user response：

In addition to Sotos' answer, you have dplyr::filter.

dplyr::filter(fish_data, names == "Fish_1")$biomass

This method can be useful for identifying several values and/or use several logical filters, in a more concise and flexible way. For example you can retrieve all the "biomass" values of the observations having "Fish" or "fish" in their "names" with dplyr::filter(fish_data, stringr::str_detect(names,"Fish|fish"))$biomass