Sampling examples.Rmd

---
title: "R Notebook"
output: html_notebook
---
```{r setup}
knitr::opts_chunk$set(paged.print = FALSE)
```

```{r}
library(tidyverse)
```

Sampling random plant IDs

```{r}
plants <- unique(ha$ha_id_number)

plant_sample <- sample(plants, 10)

ha %>% filter(ha_id_number %in% plant_sample)
```

sampling years within plants

```{r}
ha %>% slice_sample(n = 10)

ha %>% 
  group_by(ha_id_number) %>%
  slice_sample(n = 10)
```
reducing SPEI history

```{r}
ha %>% 
  mutate(spei_short = spei_history[ , 1:12])
```


take many samples (with for-loop)

```{r}
out <- vector("list", 10)

for (i in 1:10) {
  plants <- unique(ha$ha_id_number)
  
  plant_sample <- sample(plants, 10)
  
  out[[i]] <- 
    ha %>%
    filter(ha_id_number %in% plant_sample)
}
out
```


With the `purrr` package

```{r}
library(purrr)

out[[1]] %>% 
  summary(mean_ht = mean(ht, na.rm = TRUE))

means <- map_df(out, ~ .x %>% summarize(mean_ht = mean(ht, na.rm = TRUE)))

means
means %>% map_dbl(~.x$mean_ht)
```