Combining data points?


#1

I have a table with multiple data points for a species...
species temp min temp max
salt cedar 0 35
salt cedar -5 20
cheatgrass -24 15
cheatgrass 3 33

I need to combine, summarize, or merge the data so that I only have one column for each species with the overall min and max...
species temp min temp max
salt cedar -5 35
cheatgrass -24 33

I have no idea what function to use and I have only been using rstudio for a couple days.


#2

Your overall strategy is to group the data by species and then use evaluate the min and max separately for each group. This can be done in the following manner:

library(dplyr)
df <- 
  structure(
    list(species = c("salt cedar", "salt cedar", "cheatgrass", "cheatgrass"), 
         temp_min = c(0L, -5L, -24L, 3L), 
         temp_max = c(35L, 20L, 15L, 33L)), 
    .Names = c("species", "temp_min", "temp_max"), 
    class = "data.frame", 
    row.names = c(NA, -4L))

df %>% 
  group_by(species) %>% 
  summarise(temp_min = min(temp_min),
            temp_max = max(temp_max))

You may find the materials at http://r4ds.had.co.nz/transform.html helpful.