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AutoMLPipeline

is a package that makes it trivial to create complex ML pipeline structures using simple expressions. Using Julia macro programming features, it becomes trivial to symbolically process and manipulate the pipeline expressions and its elements to automatically discover optimal structures for machine learning prediction and classification.

Future work will focus on algorithms to automatically optimize the pipeline structure for any given dataset.

Load the AutoMLPipeline package and submodules

using AutoMLPipeline, AutoMLPipeline.FeatureSelectors, AutoMLPipeline.EnsembleMethods
using AutoMLPipeline.CrossValidators, AutoMLPipeline.DecisionTreeLearners, AutoMLPipeline.Pipelines
using AutoMLPipeline.BaseFilters, AutoMLPipeline.SKPreprocessors, AutoMLPipeline.Utils

Load some of filters, transformers, learners to be used in a pipeline

#### Decomposition
pca = SKPreprocessor("PCA"); fa = SKPreprocessor("FactorAnalysis"); ica = SKPreprocessor("FastICA")

#### Scaler 
rb = SKPreprocessor("RobustScaler"); pt = SKPreprocessor("PowerTransformer"); 
norm = SKPreprocessor("Normalizer"); mx = SKPreprocessor("MinMaxScaler")

#### categorical preprocessing
ohe = OneHotEncoder()

#### Column selector
catf = CatFeatureSelector(); 
numf = NumFeatureSelector()

#### Learners
rf = SKLearner("RandomForestClassifier"); 
gb = SKLearner("GradientBoostingClassifier")
lsvc = SKLearner("LinearSVC");     svc = SKLearner("SVC")
mlp = SKLearner("MLPClassifier");  ada = SKLearner("AdaBoostClassifier")
jrf = RandomForest();              vote = VoteEnsemble();
stack = StackEnsemble();           best = BestLearner();

Load data. Make sure that the input feature is a dataframe and the target output is a 1-D vector.

using CSV
profbdata = CSV.read(joinpath(dirname(pathof(AutoMLPipeline)),"../data/profb.csv"))
X = profbdata[:,2:end] 
Y = profbdata[:,1] |> Vector;
head(x)=first(x,5)
head(profbdata)

Filter categories and hot-encode them

pohe = @pipeline catf |> ohe
tr = fit_transform!(pohe,X,Y)
head(tr)

Filter numeric features, compute ica and pca features, and combine both features

pdec = @pipeline (numf |> pca) + (numf |> ica)
tr = fit_transform!(pdec,X,Y)
head(tr)

A pipeline expression example for classification using the Voting Ensemble learner

# take all categorical columns and hotbit encode each, 
# concatenate them to the numerical features,
# and feed them to the voting ensemble
pvote = @pipeline  (catf |> ohe) + (numf) |> vote
pred = fit_transform!(pvote,X,Y)
sc=score(:accuracy,pred,Y)
println(sc)
### cross-validate
crossvalidate(pvote,X,Y,"accuracy_score",5)

Print corresponding function call of the pipeline expression

@pipelinex (catf |> ohe) + (numf) |> vote
# outputs: :(Pipeline(ComboPipeline(Pipeline(catf, ohe), numf), vote))

Another pipeline example using the RandomForest learner

# compute the pca, ica, fa of the numerical columns,
# combine them with the hot-bit encoded categorial features
# and feed all to the random forest classifier
prf = @pipeline  (numf |> rb |> pca) + (numf |> rb |> ica) + (catf |> ohe) + (numf |> rb |> fa) |> rf
pred = fit_transform!(prf,X,Y)
score(:accuracy,pred,Y) |> println
crossvalidate(prf,X,Y,"accuracy_score",5)

A pipeline for the Linear Support Vector for Classification

plsvc = @pipeline ((numf |> rb |> pca)+(numf |> rb |> fa)+(numf |> rb |> ica)+(catf |> ohe )) |> lsvc
pred = fit_transform!(plsvc,X,Y)
score(:accuracy,pred,Y) |> println
crossvalidate(plsvc,X,Y,"accuracy_score",5)

Extending AutoMLPipeline

# If you want to add your own filter/transformer/learner, it is trivial. 
# Just take note that filters and transformers process the first 
# input features and ignores the target output while learners process both 
# the input features and target output arguments of the fit! function. 
# transform! function always expect one input argument in all cases. 

# First, import the abstract types and define your own mutable structure 
# as subtype of either Learner or Transformer. Also import the fit! and
# transform! functions to be overloaded. Also load the DataFrames package
# as the main data interchange format.

using DataFrames
using AutoMLPipeline.AbsTypes, AutoMLPipeline.Utils

import AutoMLPipeline.AbsTypes: fit!, transform!  #for function overloading 

export fit!, transform!, MyFilter

# define your filter structure
mutable struct MyFilter <: Transformer
  variables here....
  function MyFilter()
      ....
  end
end

# define your fit! function. 
# filters and transformer ignore the target argument. 
# learners process both the input features and target argument.
function fit!(fl::MyFilter, inputfeatures::DataFrame, target::Vector=Vector())
     ....
end

#define your transform! function
function transform!(fl::MyFilter, inputfeatures::DataFrame)::DataFrame
     ....
end

# Note that the main data interchange format is a dataframe so transform! 
# output should always be a dataframe as well as the input for fit! and transform!.
# This is necessary so that the pipeline passes the dataframe format consistently to
# its filters/transformers/learners. Once you have this filter, you can use 
# it as part of the pipeline together with the other learners and filters.

Feature Requests and Contributions

We welcome contributions, feature requests, and suggestions. Here is the link to open an issue for any problems you encounter. If you want to contribute, please follow the guidelines in contributors page.

Help usage

Usage questions can be posted in:

• Julia Community
• Gitter AutoMLPipeline Community
• Julia Discourse forum