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# An example of a logistic regression model based off Kaggle's Titanic data set.
# https://www.kaggle.com/c/titanic
# Let's define some constants we will use below later.
titles <- c(
mr = "Mr.", mrs = "Mrs.", ms = "Ms\\.|Miss\\.",
master = "Master.", rev = "Rev.", dr = "Dr."
)
fixed_titles <- c("mr", "mrs", "master", "rev", "dr")
tickets <- c(
pc = "PC", a = "A/", sc = "S.C.", ca = "C\\.A|CA",
sp = "SP|S\\.P", w = "W", soc = "SOC|S\\.O\\.C", ston = "SOTON|STON",
line = "LINE", paris = "PARIS"
)
fixed_tickets <- c("pc", "a", "sc", "w", "line", "paris")
cabin_derivations <- alist(
cabin_number = as.integer(gsub("[^0-9]+", "", cabin)),
cabin_letter = factor(gsub("[^a-zA-Z]+", "", cabin)),
cabin_fare = stats::ave(title_fare, cabin, FUN = mean)
)
# This is just so we have a temporary file to save our model to.
# At the bottom of this file, you can replace it with a static CSV path.
syberia_project()$cache_set("titanic_model", tempfile(fileext = ".rds"))
# A syberia model file is a nested list structure. Top-level lists are called
# stages. You can create your own stages by writing `lib/stages/my_stage.R`.
# A stage should return a [stagerunner](github.com/syberia/stagerunner) object.
list(
import = list(
url = list(
"https://raw.githubusercontent.com/haven-jeon/introduction_to_most_usable_pkgs_in_project/master/bicdata/data/titanic.csv",
stringsAsFactors = FALSE
)
),
# Data stage is a perfect place to transform your dataset prior to modeling
# The default data stage defines a DSL for creating and training
# [mungebits](github.com/syberia/mungebits)
# Yes, you need to train your data preparation!
# Traditionally data scientists have been preparing models and shipping them to
# engineers that would reimplement them in Java or another traditional server language.
# This is a very slow and extremely error-prone process.
#
# Also, there is one more important consideration: data preparation should
# operate differently in train versus predict!
# For example, let's say that we want to impute a missing variable using column mean.
# In training, you'd want to use the mean calculated from the import stage dataframe.
# However, in production you do not have access to the input dataframe anymore!
# So you need to store the imputed mean somewhere and use that number in production.
# Data stage takes care of this duality, allowing you to use a plethora of mungebits
# from [syberiaMungebits](github.com/syberia/syberiaMungebits). Or you can write your own
# and put them in `lib/mungebits/my_mungebit.R`
data = list(
"has paren in name" = list(multi_column_transformation(function(name) grepl("(", fixed = TRUE, name)), "name", "has_paren")
,"Name length variable" = list(new_variable, function(name) nchar(name), "name_length")
,"Formal title" = list(regex_factor, "name", "title", cases = titles, fixed = fixed_titles)
,"Ticket type" = list(regex_factor, "ticket", "ticket_type", cases = tickets, fixed = fixed_tickets)
,"title_fare variable" = list(new_variable, function(title, fare) { stats::ave(fare, title, FUN = mean) }, "title_fare")
,"class_fare" = list(multi_column_transformation(function(klass, fare) { stats::ave(fare, klass, FUN = mean) }), c("pclass", "fare"), "class_fare")
,"Some simple derivations" = list(atransform, alist(fare_diff = fare - title_fare, fare_pct = fare / title_fare, fare_diff_class = fare - class_fare, fare_pct_class = fare / class_fare))
,"Derived cabin variables" = list(atransform, cabin_derivations)
,"Cabin diff and pct" = list(atransform, alist(fare_diff_cabin = fare - cabin_fare, fare_pct_cabin = fare / cabin_fare))
,"cabin_single_letter" = list(new_variable, function(cabin_letter) factor(gsub("^(.).*$", "\\1", cabin_letter)), "cabin_single_letter")
,"Set factors" = list(!factor, c("sex", "embarked"))
,"Logical to factor" = list(!as.factor, is.logical)
,"Drop character vars" = list(drop_variables, is.character)
,"Restore levels" = list(restore_categorical_variables, is.factor)
,"Rename dep_var" = list(renamer, c("survived" = "dep_var"))
),
# Once the data is prepared and is in the right format we are ready to
# do the modeling itself.
# You can use any R package to create a *classifier*.
# Classifiers are determined by the `train` and `predict` functions.
# The output of the model stage is a [tundraContainer](github.com/syberia/tundra)
# A tundracontainer is an object that contains all the information necessary
# to make a prediction: the munge procedure, the classifier object, as well as
# the ids of the variables that were in training. This helps to ensure that
# you are not predicting on the same ids that you used for training,
# helping you make a more accurate validation. You can set `.is_var` to the id column name
# or it will default to 'id'.
# The most interesting part about a tundracontainer is its predict function.
# The predict function first runs all the mungebits in predict mode,
# then it checks that you are not predicting on train ids, and then calls the
# classifier predict method, like `predict.gbm`
model = list('gbm'
, .id_var = 'X'
, distribution = 'bernoulli'
, number_of_trees = 100 # Set to 3000 for better model.
, shrinkage_factor = 0.05 # Set to 0.005 for better model.
, depth = 5
, min_observations = 6
, train_fraction = 1
, bag_fraction = 0.5
, cv = FALSE # Uncomment lines below for cv.
# , cv_folds = 5 # For CV and/or > 1 cores need GBM globally installed.
# , number_of_cores = 1
, perf_method = 'OOB'
, prediction_type = 'response'
),
# When all is said and done you need to export the result of your hard work.
# This stage uses the same adapters as the *import* stage.
# If you need to export to a custom place you need to write a new adapter and
# implement the `write` function.
export = list(
R = "titanic",
# Change to fixed file like ~/tmp/model.rds
file = syberia_project()$cache_get("titanic_model")
)
)