Here’s a solution without loops.
# some artificial data
set.seed(1)
daf <- data.frame(species = factor(paste0("species", c(rep(1:3, 10)))),
year = rep(2000:2009, 3), x = sample(1:100, 30))
library(dplyr)
library(broom)
lm_fit <- daf %>% group_by(species) %>%
do(fit = lm(x ~ year, .))
tidy(lm_fit, fit) # or as.data.frame(tidy(lm_fit, fit)) to get a data.frame
# # A tibble: 6 x 6
# # Groups: species [3]
# species term estimate std.error statistic p.value
# <fct> <chr> <dbl> <dbl> <dbl> <dbl>
# 1 species1 (Intercept) 2508 7132 0.352 0.734
# 2 species1 year - 1.23 3.56 -0.346 0.738
# 3 species2 (Intercept) -11250 4128 -2.73 0.0260
# 4 species2 year 5.64 2.06 2.74 0.0256
# 5 species3 (Intercept) 461 7460 0.0618 0.952
# 6 species3 year - 0.206 3.72 -0.0554 0.957
library(ggplot2)
ggplot(daf, aes(x = year, y = x)) + geom_smooth(method = "lm", se = FALSE) +
facet_wrap(~species)
solved How to create a loop that will make regression models in R? [closed]