Automatically generates formula based on df column names

asformula.R

# Example of automatic formula
# How to generate and test automatically different formulas
set.seed(1)  # Makes it reproducible

library(dplyr)
library(lmerTest)

# Test data
df = data.frame(a = runif(30, 1, 10), b_sp = rnorm(30, 5, 20), 
                b_abs = runif(30, 0, 1), c_sp = rnorm(30, -3, 10),
                c_abs = runif(30, 0, 1),
                species = rep(c("specA", "specB"), each = 2, length.out = 30))

# base formula
base.formula = "a ~ (1|species) +"

# Different models
sp.formula = df %>%
  names() %>% # Get colnames of df
  grep("_sp", ., value = T)%>%  # Select names of interest
  paste(collapse = " + ") %>%  # joins all elements with '+' with spaces
  paste(base.formula, .) %>%
  as.formula()  # Converts character string to formula

b.formula = df %>%
  names() %>% # Get colnames of df
  grep("b_", ., value = T)%>%  # Select names of interest
  paste(collapse = " + ") %>%  # joins all elements with '+' with spaces
  paste(base.formula, .) %>%
  as.formula()


# Fit models
mod.sp = lmer(sp.formula, data = df)
mod.b = lmer(b.formula, data = df)