The 2021 USMS ePostal Championship Results, Working Up Data for a Shiny App

Cleaning Data for a Shiny App

The data we’ve already downloaded and named Postal contains the as-reported results from all ePostals from 1998 through 2021. Let’s take a look.

names(Postal)
## [1] "Place"           "Name"            "Age"             "USMS_ID"        
## [5] "Distance"        "Club"            "Gender"          "Year"           
## [9] "National_Record"

Pretty self explanatory column names, and quite a bit of information. There’s more though that we can tease out.

I’d like to add to Postal in the following ways:

1. Age groups. The ePostal is scored by age group, 18-24 and then by 5 year windows thereafter (25-29 etc.)
2. Athlete’s relative place within their age and gender category by year
3. An athlete’s average 50 split, based on distance traveled and assuming a 25 yard pool
4. Cleaning up USMS identification to identify athletes across years
5. Club sizes. USMS defines club sizes and scores based on those sizes, both by gender and total size by year
6. Summary stats for clubs by year
   • Total distance swam
   • Club rankings by gender
   • Average distance traveled and 50 split by gender
   • Average age by gender

Since this is headed for a Shiny app, where it will be displayed the goal will be to make information readable, which will involve some sacrifices. For example an athlete’s relative place will be a string in the form of “Athlete place of Total place” (i.e. “1 of 54”) rather than just a naked numeric.

Age Groups

Since we already have an Age column making an age group column is a simple matter of using dplyr::case_when to match the appropriate age range to the Age. We’ll do this using dplyr::between. between takes three arguments – a value x, a left and a right. If x >= left & x <= right then between returns TRUE. Otherwise between returns FASLE. The resulting code is perhaps long, and there are more compact ways to do this, but it’s also very readable, approximating written English. Readability is useful in the context of a blog entry and I’ll continue to prioritize it throughout.

Postal <- Postal %>% 
  mutate(
    Age_Group = case_when(
      between(Age, 0, 24) ~ "18-24",
      between(Age, 25, 29) ~ "25-29",
      between(Age, 30, 34) ~ "30-34",
      between(Age, 35, 39) ~ "35-39",
      between(Age, 40, 44) ~ "40-44",
      between(Age, 45, 49) ~ "45-49",
      between(Age, 50, 54) ~ "50-54",
      between(Age, 55, 59) ~ "55-59",
      between(Age, 60, 64) ~ "60-64",
      between(Age, 65, 69) ~ "65-69",
      between(Age, 70, 74) ~ "70-74",
      between(Age, 75, 79) ~ "75-79",
      between(Age, 80, 84) ~ "80-84",
      between(Age, 85, 89) ~ "85-89",
      between(Age, 90, 94) ~ "90-94",
      between(Age, 95, 99)~ "95-99",
      between(Age, 100, 104) ~ "100-104",
      TRUE ~ "NA" # if for some reason Age doesn't match any of the above this will catch it and write the string 'NA'
    )
  ) %>% 
  mutate(Age_Group = factor(Age_Group, levels = c("18-24", "25-29", "30-34", "35-39", "40-44", "45-49", "50-54", "55-59", "60-64", "65-69", "70-74", "75-79", "80-84", "85-89", "90-94", "95-99")))

# demonstration table
Postal %>%
  select(Place, Name, Distance, Year, Age, Age_Group, Gender) %>% 
  head(5) %>%
  flextable_style()

Athlete Relative Place

As discussed above the athlete place column will contain a string giving an individual athlete’s place within their age and gender category for a given year. The point is to provide a means of comparing two athletes in the Shiny app. If Athlete A and Athlete B both finished 6th, but Athlete A did so in a category with 50 entrants vs. only 10 in Athlete B’s category then that’s worth knowing when comparing them.

Here we’ll just paste an athlete’s Place, the string " of " and the maximumn place from that age group together.

Postal <- Postal %>%
  group_by(Gender, Age_Group, Year) %>% # places are caluclated by gender, age group and year
  mutate(Relative_Place = paste(Place, max(Place, na.rm = TRUE), sep = " of ")) # use paste to build string

# demonstration table
Postal %>%
  select(Place, Name, Distance, Year, Age_Group, Gender, Relative_Place) %>% 
  head(5) %>%
  flextable_style()

Average 50 Split

I’m accustomed to looking at 50 splits in swimming, and I think it’s an interesting metric by which to evaluate ePostal results as well. An athlete’s split can be calculated by converting the time (1 hour), then multiplying that number of seconds by 50 and then multiplying again by reciprocal distance to get a number in units of seconds per 50 yards. We can then round and format the result to make it pleasant to look at.

Postal <- Postal %>%
  mutate(Avg_Split_50 = (1 / Distance) * 60 * 60 * 50) %>% # compute split
  mutate(Avg_Split_50 = format(round(Avg_Split_50, 2), nsmall = 2)) # want two decimal places, even if the last one is a zero

# demonstration table
Postal %>%
  select(Place, Name, Distance, Year, Age_Group, Gender, Avg_Split_50) %>% 
  head(5) %>%
  flextable_style()

USMS_ID

The value in USMS_ID has two parts. The first four characters, before the "-" vary year to year. The last five characters, after the "-" are an athlete’s permanent identification string, used to identify athletes without relaying on names. We discuss this records matching problem a lot around here, because athlete names aren’t a stable means of identification. Sometimes people get married and change their names. Sometimes people use nicknames. Things happen and the permanant portion of the USMS_ID is a good way of handling things. Sadly ePostal results only include USMS_ID after 2010, so we need to come up with something for pre-2011 results.

Here’s the plan. We’ll break off the permanent portion of USMS_ID into a new column called Perm_ID based on the location of "-" using str_split_fixed. Rows without a USMS_ID will have an empty character string "" in Perm_ID, which we’ll convert to NA with na_if. Then we’ll group athletes by name. If any entry for that athlete, using that name, is from post-2010 they’ll have a Perm_ID which we’ll be able to copy to all rows involving that name using the tidyr::fill function. It’s of course possible to have two athletes with the same name. We could be stricter here and group_by name and club for example, but athletes do change clubs. There are other things we could try as well, like matching on age progression, but for right now we’re just going to accept that there might be some false matches.

Postal <- Postal %>%
  mutate(Perm_ID = str_split_fixed(USMS_ID, "-", n = 2)[, 2], # only want the second part of the split
         Perm_ID = na_if(Perm_ID, "")) %>%  # turn empty strings "" into NAs
  group_by(Name) %>%
  tidyr::fill(Perm_ID, .direction = "updown") # all instances of name will get non-NA value of Perm_ID - assumes there's only one unique Perm_ID for each name

Some athletes still don’t have a Perm_ID though, because they don’t have a USMS_ID listed.

# demonstration table
Postal %>%
  filter(Year == 1998) %>% 
  select(Place, Name, Year, USMS_ID, Perm_ID) %>%
  head(5) %>%
  flextable_style()

We’re going to make them fake Perm_IDs. Each fake Perm_ID will be a six character string of upper case letters. We’ll use this slightly different format (compared to the five character alphanumeric real Perm_IDs) so that it’s possible to differentiate the fake from the real.

Each unique name without a real Perm_ID needs a fake Perm_ID. Let’s first collect those unique names.

Unique_Names <- Postal %>%
  ungroup() %>%
  select(Name, Perm_ID) %>% # don't need all the columns, only these two
  filter(is.na(Perm_ID) == TRUE) %>% # want only rows where there isn't a Perm_ID
  unique() # don't need duplicates

Unique_Names %>% 
  head(5) %>%
  flextable_style()

Now we need a list of random strings, one for each name. Since we’re generating something random we’ll use set.seed to make it reproducible. Then we’ll use the stringi::stri_rand_strings function to generate a list of random strings with length 6. The length of the list will be the number of rows in unique_names.

set.seed(1) # to make random strings reproducible

Unique_Names <- Unique_Names %>% 
  mutate(Perm_ID = stringi::stri_rand_strings( # make random strings
    n = nrow(Unique_Names), # number of random strings to make
    length = 6, # number of characters in each string
    pattern = "[A-Z]" # what to make the string out of, in this case all capital letters
  ))

# demonstration table
Unique_Names %>% 
  head(5) %>%
  flextable_style()

Now we’ll join Postal and Unique_Names back up by Name and use coalesce to get non-NA values of Perm_ID for each row. Each Name, which hopefully means each athlete, now has a unique Perm_ID.

Postal <- Postal %>% 
  left_join(Unique_Names, by = "Name") %>% # attach newly made strings back to original data frame based on name
  mutate(Perm_ID = coalesce(Perm_ID.x, Perm_ID.y)) %>% # use first non-na value between original data frame (x) and new data frame (y)
  select(-Perm_ID.x, -Perm_ID.y) # don't need these columns any more

# demonstration table
Postal %>%
  filter(Year == 1998) %>% 
  select(Place, Name, Year, USMS_ID, Perm_ID) %>%
  head(5) %>%
  flextable_style()

Club Sizes

USMS defines categories of club size for the ePostal as small, medium, large and extra large based on the number of athletes representing that club. Here we’ll count the number of athletes for each club with n and categorize appropriately with case_when. It’s also interesting to look at participation by gender, so we’ll count the male and female athletes for each club using sum. We’ll get new columns of the form Club_Count (number of athletes in a club) and Club_Size (a factor with levels S, M, L, XL).

# total club size
Postal <- Postal %>% 
    group_by(Club, Year) %>% # working with clubs now, by year
    mutate(Club_Count = n()) %>% # number of athletes in each club for a given year
    mutate(Club_Size_Combined = case_when( # code in club sizes based on number of athletes
      Club_Count < 26 ~ "S",
      Club_Count < 50 ~ "M",
      Club_Count <= 100 ~ "L",
      TRUE ~ "XL"
    )) %>% 
  mutate(Club_Size_Combined = factor(Club_Size_Combined, levels = c("S", "M", "L", "XL")))

# male club size
Postal <- Postal %>% 
    group_by(Club, Year) %>%
    mutate(Club_Count_Male = sum(Gender == "M", na.rm = TRUE)) %>% # only want to count men this time
    mutate(Club_Size_Male = case_when(
      Club_Count_Male < 26 ~ "S",
      Club_Count_Male < 50 ~ "M",
      Club_Count_Male <= 100 ~ "L",
      TRUE ~ "XL"
    )) %>% 
    mutate(Club_Size_Male = factor(Club_Size_Male, levels = c("S", "M", "L", "XL")))

# female club size
Postal <- Postal %>% 
    group_by(Club, Year) %>%
    mutate(Club_Count_Female = sum(Gender == "W", na.rm = TRUE)) %>% # only want to count women this time
    mutate(Club_Size_Female = case_when(
      Club_Count_Female < 26 ~ "S",
      Club_Count_Female < 50 ~ "M",
      Club_Count_Female <= 100 ~ "L",
      TRUE ~ "XL"
    )) %>% 
    mutate(Club_Size_Female = factor(Club_Size_Female, levels = c("S", "M", "L", "XL")))

# demonstration table
Postal %>%
  select(Club, Year, Club_Count, Club_Size_Combined, Club_Size_Male) %>% 
  head(5) %>%
  flextable_style()

Club Summary Stats

In addition to making comparisons between athletes we can also make comparisons between clubs.

# total club stats
Postal <- Postal %>%
  mutate(Distance = na_if(Distance, 0)) %>% # shouldn't be any distance NA values, but convert to zero if there are
  group_by(Club, Year) %>%
  mutate(Total_Distance_Combined = sum(Distance, na.rm = TRUE)) %>% # add up distance for each club/year
  mutate(Avg_Distance_Combined = Total_Distance_Combined / Club_Count) %>% # calculate avg distance per athlete
  mutate(Avg_Distance_Combined = round(Avg_Distance_Combined, 0))# don't want decimal places


# male stats
Postal <- Postal %>%
  group_by(Club, Year) %>%
  mutate(Total_Distance_Male = sum(Distance[Gender == "M"], na.rm = TRUE)) %>%
  mutate(Avg_Distance_Male = Total_Distance_Male / Club_Count_Male) %>%
  mutate(Avg_Distance_Male = round(Avg_Distance_Male, 0))

# female stats
Postal <- Postal %>%
  group_by(Club, Year) %>%
  mutate(Total_Distance_Female = sum(Distance[Gender == "W"], na.rm = TRUE)) %>%
  mutate(Avg_Distance_Female = Total_Distance_Female / Club_Count_Female) %>%
  mutate(Avg_Distance_Female = round(Avg_Distance_Female, 0))

# demonstration table
Postal %>%
  filter(Gender == "W") %>% 
  select(Club, Year, Total_Distance_Female, Avg_Distance_Female) %>% 
  head(5) %>%
  flextable_style()