Predict fish phenology: advanced

Overview

The function predict_phenolgy() is purposefully kept fairly simple so it can be expanded to iterate across datasets. Typically, this will take the form of loops or vectorizing in R (functions of the map() famimy from purrr and apply() family from base). There are many reasons why you might want to iterate, including predicting over multiple years, multiple sites, predicting hatch or emergence simultaneously, or even using multiple potential spawn dates. We’ll show some examples below (moving from less to more complicated). First, we load packages:

library(hatchR) # for data and phenology modeling
library(ggplot2) # for additional plotting options
library(purrr) # for iteration
library(lubridate) # for date manipulation
library(tibble) # for data manipulation
library(dplyr) # for data manipulation
library(tidyr) # for data manipulation

Multiple spawn dates

Given the example we used in the Predict Phenology-Basic vignette, perhaps we now want to expand it to predict multiple spawn dates (e.g., the early, peak, and late part of the spawning distribution) for the Woody Island population in Lake Iliamna. Using Table 1 from Sparks et al. (2019) we see that the spawning range is between August 14 and September 3rd, with the peak occurring August 18th. We can set these dates up as a vector to run the model over.

WI_spawn_dates <- c("1990-08-14", "1990-08-18", "1990-09-3")

The we will go through the typical process of getting the model parameterized as we did previously.

sockeye_hatch_mod <- model_select(
  author = "Beacham and Murray 1990",
  species = "sockeye",
  model_id = 2,
  development_type = "hatch"
)

Now we can automate the model. We’ll demonstrate two ways—a loop and a vectorized approach.

Looping

We will show an example of how to set up a for loop to run through each element of the woody_island dataset.

# Loop storage objects
OUT_loop_all <- NULL
OUT_loop_d2h <- NULL

# Loop body
for (d in 1:length(WI_spawn_dates)) { # d will be our numerical iterator

  # subset the element d of the vector and assign to object
  WI_spawn <- WI_spawn_dates[d]

  # predict phenology
  WI_hatch <- predict_phenology(
    data = woody_island,
    dates = date,
    temperature = temp_c,
    spawn.date = WI_spawn,
    model = sockeye_hatch_mod
  )

  ### ALL output ###
  # do this if we want to maintain all info predict_phenology
  OUT_loop_all[[d]] <- WI_hatch

  ### A single element of output ###
  # alternatively, subsets out output
  temp <- tibble(matrix(data = NA, ncol = 2, nrow = 1)) # empty dataframe to add in data
  colnames(temp) <- c("spawn_date", "days_2_hatch") # change column names
  temp$spawn_date <- WI_spawn # assign spawn date
  temp$days_2_hatch <- WI_hatch$days2done # assign days to hathc
  OUT_loop_d2h <- rbind(OUT_loop_d2h, temp) # row bind temp object and OUT object
}

Inspect the loop output:

glimpse(OUT_loop_all)
#> List of 3
#>  $ :List of 4
#>   ..$ days_to_develop: int 71
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-14"
#>   .. ..$ stop : Date[1:1], format: "1990-10-23"
#>   ..$ ef_table       : tibble [71 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 74
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-18"
#>   .. ..$ stop : Date[1:1], format: "1990-10-30"
#>   ..$ ef_table       : tibble [74 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 110
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-09-03"
#>   .. ..$ stop : Date[1:1], format: "1990-12-21"
#>   ..$ ef_table       : tibble [110 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr>

You can also see we made a tibble of dates and predicted days to hatch:

OUT_loop_d2h
#> # A tibble: 3 × 1
#>   spawn_date
#>   <chr>     
#> 1 1990-08-14
#> 2 1990-08-18
#> 3 1990-09-3

If you don’t want the full output of each run of predict_phenolgy() and you just for example want the predicted days to hatch, then it’s easier to access those elements within the loop as demonstrated with the temp object section demonstrated in the loop.

Vectorizing

Mapping

Vectorizing, while historically about prioritizing speed, is now more about making your code more readable (see Chapter 26 in R for Data Science and chapter 9 in Advanced R).

We’ll demonstrate using purrr::map(). If you are unfamiliar with mapping but want to learn more about how it works and it’s power, we highly recommend the linked chapters from R for Data Science and Advanced R.

# map works by applying a function over a list (our vector is a very simple list)
# if you are familiar with apply() functions, map is essentially the same

results_map <- map(
  WI_spawn_dates, # vector we are mapping over
  predict_phenology, # function we are mapping with (note no "()"),
  data = woody_island, # additional arguments required by predict_phenology
  dates = date,
  temperature = temp_c,
  model = sockeye_hatch_mod
)

# we now have a list of lists the same as OUT_loop
glimpse(results_map)
#> List of 3
#>  $ :List of 4
#>   ..$ days_to_develop: int 71
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-14"
#>   .. ..$ stop : Date[1:1], format: "1990-10-23"
#>   ..$ ef_table       : tibble [71 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 74
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-18"
#>   .. ..$ stop : Date[1:1], format: "1990-10-30"
#>   ..$ ef_table       : tibble [74 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 110
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-09-03"
#>   .. ..$ stop : Date[1:1], format: "1990-12-21"
#>   ..$ ef_table       : tibble [110 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr>

# we can then access days to hatch easily as such
results_map |> map_dbl("days_to_develop")
#> [1]  71  74 110

Apply

While tidyverse packages like purrr have become quite popular, the base functionality of R has long had a set of functions to do similar things as map. They are called the apply family. Because hatchR is built using much of the functionality of the tidyverse we opt for using purrr:::map() over apply() functions, however we will demonstrate a similar workflow as above using the apply family.

# lapply() is the equivalent function as map() in the apply family
# they both output lists

results_lapply <- lapply(WI_spawn_dates, # vector we are mapping over
  predict_phenology, # function we are mapping with (note no "()"),
  data = woody_island, # additional arguments required by predict phenology
  dates = date,
  temperature = temp_c,
  model = sockeye_hatch_mod
)

You can see that lapply() and purrr::map() output the same results:

glimpse(results_lapply)
#> List of 3
#>  $ :List of 4
#>   ..$ days_to_develop: int 71
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-14"
#>   .. ..$ stop : Date[1:1], format: "1990-10-23"
#>   ..$ ef_table       : tibble [71 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 74
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-18"
#>   .. ..$ stop : Date[1:1], format: "1990-10-30"
#>   ..$ ef_table       : tibble [74 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ :List of 4
#>   ..$ days_to_develop: int 110
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-09-03"
#>   .. ..$ stop : Date[1:1], format: "1990-12-21"
#>   ..$ ef_table       : tibble [110 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr>

Iterating over multiple variables

An obvious extension of the example above is to use sites with multiple years of data and to predict hatch and emergence. In the example from the Predict Phenology-Basic vignette, we saw we had some days where the logger appeared to be out of the water, so let’s use a cleaner dataset.

In this example we will use temperature from the Crooked River, a tributary of the Boise River in Idaho, USA, from a reach with known bull trout spawning. The dataset is included as crooked_river.

# look at data structure
glimpse(crooked_river)
#> Rows: 1,826
#> Columns: 2
#> $ date   <dttm> 2010-12-01, 2010-12-02, 2010-12-03, 2010-12-04, 2010-12-05, 20…
#> $ temp_c <dbl> 1.1638020, 1.3442852, 1.2533443, 1.0068728, 1.2899153, 1.229158…

# visually check data
plot_check_temp(
  data = crooked_river,
  dates = date,
  temperature = temp_c,
  temp_min = 0,
  temp_max = 12
)

We can use the functionality of dplyr to do a datacheck that shows the number of observations per year:

crooked_river |>
  mutate(year = lubridate::year(date)) |>
  group_by(year) |>
  tally()
#> # A tibble: 6 × 2
#>    year     n
#>   <dbl> <int>
#> 1  2010    31
#> 2  2011   365
#> 3  2012   366
#> 4  2013   365
#> 5  2014   365
#> # ℹ 1 more row

We see we have 5 full years of data to use. For the sake of this exercise, let’s assume bull trout spawning in this system starts September 1st, peaks September 15th, and is mostly done by September 30th.

Remember, our data starts just barely in 2010, so our spawning years would be 2011-2015. However we may not have enough days of record to make predictions for 2015 so best to check that first.

First let’s just check to see if fish spawning in 2015 would have enough data to hatch and emerge.

# select bull trout hatch and emergence models
bull_hatch_mod <- model_select(
  author = "Austin et al. 2017",
  species = "bull trout",
  model = "MM",
  development_type = "hatch" # note we are using hatch model here
)

bull_emerge_mod <- model_select(
  author = "Austin et al. 2017",
  species = "bull trout",
  model = "MM",
  development_type = "emerge" # note we are using emerge model here
)

# set spawning dates in 2015
dates_2015 <- c("2015-09-01", "2015-09-15", "2015-09-30")

## hatch first
hatch_2015 <- dates_2015 |> purrr::map(
  predict_phenology,
  data = crooked_river,
  dates = date,
  temperature = temp_c,
  model = bull_hatch_mod
)

See how we receive 2 seperate warning messages saying: “FFish did not accrue enough effective units to develop. Did your fish spawn too close to the end of your data? Spawn date is _____”. It tells us the spawn date we used so we can reference which date isn’t working if we use an string of multiple dates to predict over.

If fish aren’t hatching they definitely are not going to emerge, so we won’t use 2015.

Looping

We will build a nested loop to automate over model selection variables and then over the dates. So the order of applying the predict_phenology() function in the loop example below is as follows:

Predict hatch
- 2011 spawn dates
- …
- 2014 spawn dates
Predict emergence
- 2011 spawn dates
- …
- 2014 spawn dates

## mini loop to make vector of dates
spawn_dates <- NULL
for (year in 2011:2014) {
  temp_dates <- c(paste0(year, "-09-01"), paste0(year, "-09-15"), paste0(year, "-09-30"))
  spawn_dates <- c(spawn_dates, temp_dates)
}
spawn_dates
#>  [1] "2011-09-01" "2011-09-15" "2011-09-30" "2012-09-01" "2012-09-15"
#>  [6] "2012-09-30" "2013-09-01" "2013-09-15" "2013-09-30" "2014-09-01"
#> [11] "2014-09-15" "2014-09-30"

### loop for prediction
OUT <- NULL
i <- 1 # build a counter for adding to our list of lists (OUT)

for (mod in c("hatch", "emerge")) { # loop for hatch and emerge

  # here we just iterate model selection over the two hatch and emerge options
  # in the first for loop
  dev_mod <- model_select(
    author = "Austin et al. 2017",
    species = "bull trout",
    model = "MM",
    development_type = mod
  )

  for (d in 1:length(spawn_dates)) { # nested loop over spawn dates

    # here we iterate over every date of spawn_dates but run this loop twice,
    # once for each value of the first for loop

    spawn <- spawn_dates[d] # get spawn date

    temp <- predict_phenology(
      data = crooked_river,
      dates = date,
      temperature = temp_c,
      spawn.date = spawn,
      model = dev_mod
    ) # notice we are calling the mod we set in the fist loop

    OUT[[i]] <- temp

    i <- i + 1 # add to your counter
  }
}

The output of this loop is again a list of lists. This time 24 lists that comprise the elements of each predict_phenology() iteration. Simply, the loop selects the hatch model, runs it for every date in our vector (spawn_dates) and then switches over to an emerge model and does the same thing. The point of having an iterator (i) is that we can make a new list addition to OUT for every combination of the dev_mod (hatch and emerge) and the 12 dates we want to run—resulting in 24 total individual lists that are appended to our OUT list of lists as we walk through each iteration of the for loop.

If that sounds a bit complicated, it’s because it is. And this is where the vectorized approaches really shine.

A quick note about accessing lists. Even if you want to write loops instead of vectorizing, we do recommend accessing those results via a vectorized approach. It’s hard to pull out a lot of information from from very large nested loops. You would probably write a custom loop to do so. However, those results are easily accessed by map, like so:

mapped_results <- OUT |> purrr:::map_df("ef.tibble")
mapped_results
#> # A tibble: 0 × 0

The above code outputs the ef.tibble element from every one of your lists from each combination of spawn date and phenology type into a dataframe like object which can then easily be plotted. Notice, we now use purrr::map_df() because we know the list element we are accessing is in the format of a dataframe type object (a tibble).

Vectorizing

We’ll use the purrr function purrr::pmap() to vectorize our multiple-input map function. Let’s again set up our iterative variables. We’ll do the same workflow as the past example but now exclusively with mapping.

# slightly cleaner spawn dates with map output is a list of vectors
spawn_dates <- map(
  c(2011:2014), # year vector to map for custom function
  function(year) { # custom function to make dates
    c(
      paste0(year, "-09-01"),
      paste0(year, "-09-15"),
      paste0(year, "-09-30")
    )
    }
  ) |> 
  unlist()

dev_mods <- map(
  c("hatch", "emerge"),
  model_select,
  author = "Austin et al. 2017",
  species = "bull trout",
  model = "MM"
  )

# we then set up a variable grid for all combinations of our models and dates
# it is very important to make the names of the columns in var_grid to match the
# arguments of the predict_phenology function (e.i., model = and spawn.date =)

var_grid <- expand_grid(model = dev_mods, spawn.date = spawn_dates)
head(var_grid)
#> # A tibble: 6 × 2
#>   model              spawn.date
#>   <list>             <chr>     
#> 1 <spc_tbl_ [1 × 5]> 2011-09-01
#> 2 <spc_tbl_ [1 × 5]> 2011-09-15
#> 3 <spc_tbl_ [1 × 5]> 2011-09-30
#> 4 <spc_tbl_ [1 × 5]> 2012-09-01
#> 5 <spc_tbl_ [1 × 5]> 2012-09-15
#> # ℹ 1 more row

### multiple input mapping

crooked_predictions <- pmap(var_grid, # combos of variables to iterate over
  predict_phenology, # function
  data = crooked_river, # additional arguments required by function
  dates = date,
  temperature = temp_c
)

Now that we’ve demonstrated both loops and mapping to get at iterating over multiple variables, let’s verify our results match.

# loop predictions
preds_loop <- OUT |> map_dbl("days_to_develop")
preds_pmap <- crooked_predictions |> map_dbl("days_to_develop")

# everything matches!
preds_loop == preds_pmap
#>  [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
#> [16] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE

Getting usable output

Because the basic output of these iterative processes are big lists of lists, it can be a little annoying to access all that data. However, this is again were the different flavors of map can be our friend. We’ve already shown examples of how to access the predictions, but predict_phenology() outputs much more data than just point estimates.

First we’ll demonstrate an example of how we can take those prediction and use them to create an object that’s useful for plotting.

# get predictions
days <- crooked_predictions |>
  map_dbl("days_to_develop")

# make a vector of what type of phenology we were predicting
# remember we ran hatch over 15 spawn dates then emerge over thos same 15
phenology <- c(rep("hatch", 12), rep("emerge", 12))

# make a vector of our spawn dates replicated twice and turn into a timepoint
spawning <- rep(spawn_dates, 2) |>
  ymd(tz = "UTC") # we do this because the crooked_river dataset is ymd_hms

# put them all together in an object
bull_trout_phenology <- tibble(phenology, spawning, days)
head(bull_trout_phenology)
#> # A tibble: 6 × 3
#>   phenology spawning             days
#>   <chr>     <dttm>              <dbl>
#> 1 hatch     2011-09-01 00:00:00    88
#> 2 hatch     2011-09-15 00:00:00   106
#> 3 hatch     2011-09-30 00:00:00   124
#> 4 hatch     2012-09-01 00:00:00    89
#> 5 hatch     2012-09-15 00:00:00   104
#> # ℹ 1 more row

We could then make a plot with our original data:

# filter crooked_river to correct size
crooked_river_11_15 <- crooked_river |> filter(date < ymd_hms("2015-06-01 00:00:00"))

ggplot(data = crooked_river_11_15, aes(x = date, y = temp_c)) +
  geom_point(size = 0.25) +
  geom_line() +
  geom_point(
    data = bull_trout_phenology,
    aes(x = spawning, y = 10), color = "darkblue", shape = 25, size = 2.5
  ) +
  geom_point(
    data = bull_trout_phenology |> filter(phenology == "hatch"),
    aes(x = spawning + days(days), y = 0),
    color = "darkgreen", shape = 24, size = 2.5
  ) +
  geom_point(
    data = bull_trout_phenology |> filter(phenology == "emerge"),
    aes(x = spawning + days(days), y = 0),
    color = "darkorange", shape = 24, size = 2.5
  ) +
  labs(
    title = "Crooked River Bull Trout Developmental Phenology",
    subtitle = "Blue = Spawn, Green = Hatch, Orange = Emerge",
    x = "Date",
    y = "Temperature"
  ) +
  theme_classic()

Not the best looking plot, but a good example of how to translate output to a visual representation. For better looking plots, please see the Advanced plotting vignette.

Other data types you might want might include the tibble with dates, temperature, and values and cumulative sums of effective values or the, alternatively, the developmental period.

# the tibble with all temperature and effective values for each phenological period
all_data <- crooked_predictions |>
  map_df("ef_table")
head(all_data)
#> # A tibble: 6 × 5
#>   index dates               temperature ef_vals ef_cumsum
#>   <dbl> <dttm>                    <dbl>   <dbl>     <dbl>
#> 1   275 2011-09-01 00:00:00        6.65  0.0148    0.0148
#> 2   276 2011-09-02 00:00:00        6.45  0.0144    0.0292
#> 3   277 2011-09-03 00:00:00        6.46  0.0144    0.0436
#> 4   278 2011-09-04 00:00:00        6.66  0.0148    0.0584
#> 5   279 2011-09-05 00:00:00        6.88  0.0152    0.0736
#> # ℹ 1 more row

# the phenological durations for each prediction set
development_period <- crooked_predictions |>
  map_df("dev.period")
head(development_period)
#>        start       stop
#> 1 2011-09-01 2011-11-27
#> 2 2011-09-15 2011-12-29
#> 3 2011-09-30 2012-01-31
#> 4 2012-09-01 2012-11-28
#> 5 2012-09-15 2012-12-27
#> 6 2012-09-30 2013-01-29

Naming your lists

A problem with this approach is that you end up with very large lists of lists without labels which require you to remember the data structure you feed to your mapping function. However, purrr does have a method to get around this which is the purrr::set_names() function which you would pipe into your mapping function.

# to use the simple Iliamna Lake example within a single season
WI_named_list <- WI_spawn_dates |>
  set_names() |>
  map(predict_phenology, # note we leave out the input row (WI_spawn_dates) because we are piping it in as input
    data = woody_island, # additional arguments required by predict phenology
    dates = date,
    temperature = temp_c,
    model = sockeye_hatch_mod
  )

# you can now see each list is named according to its respective spawn date
glimpse(WI_named_list)
#> List of 3
#>  $ 1990-08-14:List of 4
#>   ..$ days_to_develop: int 71
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-14"
#>   .. ..$ stop : Date[1:1], format: "1990-10-23"
#>   ..$ ef_table       : tibble [71 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ 1990-08-18:List of 4
#>   ..$ days_to_develop: int 74
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-08-18"
#>   .. ..$ stop : Date[1:1], format: "1990-10-30"
#>   ..$ ef_table       : tibble [74 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr> 
#>  $ 1990-09-3 :List of 4
#>   ..$ days_to_develop: int 110
#>   ..$ dev.period     :'data.frame':  1 obs. of  2 variables:
#>   .. ..$ start: Date[1:1], format: "1990-09-03"
#>   .. ..$ stop : Date[1:1], format: "1990-12-21"
#>   ..$ ef_table       : tibble [110 × 5] (S3: tbl_df/tbl/data.frame)
#>   ..$ model_specs    : spc_tbl_ [1 × 5] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
#>   .. ..- attr(*, "spec")=List of 3
#>   .. .. ..- attr(*, "class")= chr "col_spec"
#>   .. ..- attr(*, "problems")=<externalptr>

# therefore a single elemet could be accessed with its name and the $ operator
# if we wanted the dev.period for fish spawning on August 18th we would do the following

WI_named_list$`1990-08-18`$dev.period
#>        start       stop
#> 1 1990-08-18 1990-10-30

This approach works well for the example above, but not so well with our examples with purrr::pmap() because the variable grid we create has a bunch of expressions which don’t work for naming lists. However, if we were to do a purrr::pmap() example where it was a site x dates combination, that still work and would name the lists according to their site and then the date used to predict phenology (e.g. named_list$site1$`date`$dev.period)

References

Sparks, Morgan M., Jeffrey A. Falke, Thomas P. Quinn, Milo D. Adkison, Daniel E. Schindler, Krista Bartz, Dan Young, and Peter A. H. Westley. 2019. “Influences of Spawning Timing, Water Temperature, and Climatic Warming on Early Life History Phenology in Western Alaska Sockeye Salmon.” Canadian Journal of Fisheries and Aquatic Sciences 76 (1): 123–35. https://doi.org/10.1139/cjfas-2017-0468.

Morgan Sparks, Bryan M. Maitland

Overview

Multiple spawn dates

Looping

Vectorizing

Mapping

Apply

Iterating over multiple variables

Looping

Vectorizing

Getting usable output

Naming your lists

References