Training parameters

    Note.

    Training on GPU requires NVIDIA Driver of version 390.xx or higher.

    ParameterDescriptionDefault value
    Common parameters
    loss_function

    The metric to use in training. The specified value also determines the machine learning problem to solve. Some metrics support optional parameters (see the Objectives and metrics section for details on each metric).

    Format:
    <Metric>[:<parameter 1>=<value>;..;<parameter N>=<value>]
    Supported metrics:
    • RMSE
    • Logloss
    • MAE
    • CrossEntropy
    • Quantile
    • LogLinQuantile
    • Lq
    • MultiClass
    • MultiClassOneVsAll
    • MAPE
    • Poisson
    • PairLogit
    • PairLogitPairwise
    • QueryRMSE
    • QuerySoftMax
    • YetiRank
    • YetiRankPairwise
    For example, use the following construction to calculate the value of Quantile with the coefficient :
    Quantile:alpha=0.1
    RMSE
    custom_loss

    Metric values to output during training. These functions are not optimized and are displayed for informational purposes only. Some metrics support optional parameters (see the Objectives and metrics section for details on each metric)..

    Format:
    <Metric>[:<parameter 1>=<value>;..;<parameter N>=<value>]
    Supported metrics:
    • RMSE
    • Logloss
    • MAE
    • CrossEntropy
    • Quantile
    • LogLinQuantile
    • Lq
    • MultiClass
    • MultiClassOneVsAll
    • MAPE
    • Poisson
    • PairLogit
    • PairLogitPairwise
    • QueryRMSE
    • QuerySoftMax
    • SMAPE
    • Recall
    • Precision
    • F1
    • TotalF1
    • Accuracy
    • BalancedAccuracy
    • BalancedErrorRate
    • Kappa
    • WKappa
    • LogLikelihoodOfPrediction
    • AUC
    • R2
    • MCC
    • BrierScore
    • HingeLoss
    • HammingLoss
    • ZeroOneLoss
    • MSLE
    • MedianAbsoluteError
    • PairAccuracy
    • AverageGain
    • PFound
    • NDCG
    • PrecisionAt
    • RecallAt
    • MAP
    • CtrFactor
    Examples:
    • Calculate the value of CrossEntropy:

      c('CrossEntropy')
      Or simply:
      'CrossEntropy'
    • Calculate the values of Logloss and AUC:

      c('Logloss', 'AUC')
    • Calculate the value of Quantile with the coefficient 
      c('Quantile:alpha=0.1')

    Values of all custom metrics for learn and validation datasets are saved to the Metric output files (learn_error.tsv and test_error.tsv respectively). The directory for these files is specified in the --train-dir (train_dir) parameter.

    None (use one of the metrics supported by the library)
    eval_metric

    The metric used for overfitting detection (if enabled) and best model selection (if enabled). Some metrics support optional parameters (see the Objectives and metrics section for details on each metric).

    Format:
    <Metric>[:<parameter 1>=<value>;..;<parameter N>=<value>]
    Supported metrics:
    • RMSE
    • Logloss
    • MAE
    • CrossEntropy
    • Quantile
    • LogLinQuantile
    • Lq
    • MultiClass
    • MultiClassOneVsAll
    • MAPE
    • Poisson
    • PairLogit
    • PairLogitPairwise
    • QueryRMSE
    • QuerySoftMax
    • SMAPE
    • Recall
    • Precision
    • F1
    • TotalF1
    • Accuracy
    • BalancedAccuracy
    • BalancedErrorRate
    • Kappa
    • WKappa
    • LogLikelihoodOfPrediction
    • AUC
    • R2
    • MCC
    • BrierScore
    • HingeLoss
    • HammingLoss
    • ZeroOneLoss
    • MSLE
    • MedianAbsoluteError
    • PairAccuracy
    • AverageGain
    • PFound
    • NDCG
    • PrecisionAt
    • RecallAt
    • MAP
    Quantile:alpha=0.3
    Optimized objective is used
    iterations

    The maximum number of trees that can be built when solving machine learning problems.

    When using other parameters that limit the number of iterations, the final number of trees may be less than the number specified in this parameter.

    1000
    learning_rate

    The learning rate.

    Used for reducing the gradient step.

    The default value is defined automatically based on the dataset properties and training parameters if all of the following conditions are met:

    • The binary classification machine learning problem is being solved.

    • Some parameters are not set (refer to the list)

    The value is set to 0.03 otherwise.

    random_seed

    The random seed used for training.

    0
    l2_leaf_reg

    L2 regularization coefficient. Used for leaf value calculation.

    Any positive values are allowed.

    3
    bootstrap_type

    Bootstrap type. Defines the method for sampling the weights of objects.

    Supported methods:

    • Poisson (supported for GPU only)
    • Bayesian
    • Bernoulli
    • No
    Bayesian
    bagging_temperature

    Defines the settings of the Bayesian bootstrap. It is used by default in classification and regression modes.

    Use the Bayesian bootstrap to assign random weights to objects.

    The weights are sampled from exponential distribution if the value of this parameter is set to “1”. All weights are equal to 1 if the value of this parameter is set to “0”.

    Possible values are in the range . The higher the value the more aggressive the bagging is.

    1
    subsample
    Sample rate for bagging. This parameter can be used if one of the following bootstrap types is defined:
    • Poisson
    • Bernoulli
    0.66
    sampling_frequency

    Frequency to sample weights and objects when building trees.

    Supported values:
    • PerTree
    • PerTreeLevel
    PerTreeLevel
    random_strength

    Score the standard deviation multiplier. Use this parameter to avoid overfitting the model.

    The value of this parameter is used when selecting splits. On every iteration each possible split gets a score (for example, the score indicates how much adding this split will improve the loss function for the training dataset). The split with the highest score is selected.

    The scores have no randomness. A normally distributed random variable is added to the score of the feature. It has a zero mean and a variance that decreases during the training. The value of this parameter is the multiplier of the variance.

    1
    use_best_model
    If this parameter is set, the number of trees that are saved in the resulting model is defined as follows:
    1. Build the number of trees defined by the training parameters.
    2. Use the validation dataset to identify the iteration with the optimal value of the metric specified in  --eval-metric (eval_metric).

    No trees are saved after this iteration.

    This option requires a validation dataset to be provided.

    True if a validation set is input (the train_pool parameter is defined) and at least one of the label values of objects in this set differs from the others. False otherwise.

    best_model_min_trees

    The minimal number of trees that the best model should have. If set, the output model contains at least the given number of trees even if the best model is located within these trees.

    Should be used with the use_best_model parameter.

    None (The minimal number of trees for the best model is not set)
    train_pool
    The validation set for the following processes:
    None
    depth

    Depth of the tree.

    The range of supported values depends on the processing unit type and the type of the selected loss function:
    • CPU — Any integer up to  16.

    • GPU — Any integer up to 8 pairwise modes (YetiRank, PairLogitPairwise and QueryCrossEntropy) and up to   16 for all other loss functions.

    6
    ignored_features

    Indices of features to exclude from training. The non-negative indices that do not match any features are successfully ignored. For example, if five features are defined for the objects in the dataset and this parameter is set to “42”, the corresponding non-existing feature is successfully ignored.

    The identifier corresponds to the feature's index. Feature indices used in train and feature importance are numbered from 0 to featureCount – 1. If a file is used as input data then any non-feature column types are ignored when calculating these indices. For example, each row in the input file contains data in the following order: categorical feature<\t>label value<\t>numerical feature. So for the row rock<\t>0<\t>42, the identifier for the “rock” feature is 0, and for the “42” feature it's 1.

    The identifiers of features to exclude should be enumerated at vector.

    For example, if training should exclude features with the identifiers 1, 2, 7, 42, 43, 44, 45, the value of this parameter should be set to c(1,2,7,42,43,44,45).

    None (use all features)
    one_hot_max_size

    Use one-hot encoding for all features with a number of different values less than or equal to the given parameter value. Ctrs are not calculated for such features.

    2

    has_time

    Use the order of objects in the input data (do not perform random permutations during the Transforming categorical features to numerical features and Choosing the tree structure stages).

    The Timestamp column type is used to determine the order of objects if specified in the input data.

    FALSE (not used; generate random permutations)
    rsm

    Random subspace method. The percentage of features to use at each split selection, when features are selected over again at random.

    The value must be in the range (0;1].

    1
    nan_mode

    The method to process NaN values in the input dataset.

    Possible values:
    • Forbidden — NaN values are not supported, their presence raises an exception.
    • Min — Each NaN float feature is processed as the minimum value from the dataset.
    • Max — Each NaN float feature is processed as the maximum value from the dataset.
    Note.

    The method for processing NaN values can also be set in the Custom quantization borders and NaN modes input file. Such values override the ones specified in this parameter.

    Min
    fold_permutation_block_size

    Objects in the dataset are grouped in blocks before the random permutations. This parameter defines the size of the blocks. The smaller is the value, the slower is the training. Large values may result in quality degradation.

    Default value differs depending on the dataset size and ranges from 1 to 256 inclusively
    leaf_estimation_iterations

    The number of gradient steps when calculating the values in leaves.

    Depends on the training objective
    leaf_estimation_method

    The method used to calculate the values in leaves.

    Possible values:
    • Newton
    • Gradient
    Default value depends on the selected metric
    nameThe experiment name to display in visualization tools.experiment
    fold_len_multiplier

    Coefficient for changing the length of folds.

    The value must be greater than 1. The best validation result is achieved with minimum values.

    With values close to 1 (for example, ), each iteration takes a quadratic amount of memory and time for the number of objects in the iteration. Thus, low values are possible only when there is a small number of objects.

    2
    approx_on_full_history

    The principles for calculating the approximated values.

    Possible values:
    • “TRUE” — Use all the preceding rows in the fold for calculating the approximated values. This mode is slower and in rare cases slightly more accurate.
    • “FALSE” — Use only а fraction of the fold for calculating the approximated values. The size of the fraction is calculated as follows: , where X is the specified coefficient for changing the length of folds. This mode is faster and in rare cases slightly less accurate
    TRUE
    class_weights

    Class weights. The values are used as multipliers for the object weights. This parameter can be used for solving classification and multiclassification problems.

    For example, class_weights <- c(0.1, 4) multiplies the weights of objects from class 0 by 0.1 and the weights of objects from class 1 by 4.

    None (the weight for all classes is set to 1)
    boosting_type

    Boosting scheme.

    Possible values:
    • Ordered — Usually provides better quality on small datasets, but it may be slower than the Plain scheme.
    • Plain — The classic gradient boosting scheme.
    Depends on the number of objects in the training dataset and the selected learning mode
    allow_const_label

    Use it to train models with datasets that have equal label values for all objects.

    False
    cat_features

    A vector of categorical features indices.

    The indices are zero-based and can differ from the ones given in the Column descriptions file.

    NULL (it is assumed that all columns are the values of numerical features)
    Overfitting detection settings
    od_type

    The type of the overfitting detector to use.

    Possible values:
    • IncToDec
    • Iter
    IncToDec
    od_pval

    The threshold for the IncToDec overfitting detector type. The training is stopped when the specified value is reached. Requires that a validation dataset was input.

    For best results, it is recommended to set a value in the range .

    The larger the value, the earlier overfitting is detected.

    Restriction.

    Do not use this parameter with the Iter overfitting detector type.

    0 (the overfitting detection is turned off)
    od_waitThe number of iterations to continue the training after the iteration with the optimal metric value.
    The purpose of this parameter differs depending on the selected overfitting detector type:
    • IncToDec — Ignore the overfitting detector when the threshold is reached and continue learning for the specified number of iterations after the iteration with the optimal metric value.
    • Iter — Consider the model overfitted and stop training after the specified number of iterations since the iteration with the optimal metric value.
    20
    early_stopping_roundsSet the overfitting detector type to Iter and stop the training after the specified number of iterations since the iteration with the optimal metric value.FALSE
    Binarization settings
    border_count

    The number of splits for numerical features. Allowed values are integers from 1 to 255 inclusively.

    254 (if training is performed on CPU) or 128 (if training is performed on GPU)
    feature_border_type

    The binarization mode for numerical features.

    Possible values:
    • Median
    • Uniform
    • UniformAndQuantiles
    • MaxLogSum
    • MinEntropy
    • GreedyLogSum
    GreedyLogSum
    Multiclassification settings
    classes_count

    The upper limit for the numeric class label. Defines the number of classes for multiclassification.

    Only non-negative integers can be specified. The given integer should be greater than any of the label values.

    If this parameter is specified the labels for all classes in the input dataset should be smaller than the given value

    maximum class label + 1

    Performance settings
    thread_count

    The number of threads to use during training.

    Optimizes the speed of execution. This parameter doesn't affect results.

    -1 (the number of threads is equal to the number of cores) (The number of processor cores)
    Processing units settings
    task_type

    The processing unit type to use for training.

    Possible values:
    • CPU
    • GPU
    CPU
    devices

    IDs of the GPU devices to use for training (indices are zero-based).

    Format

    • <unit ID> for one device (for example, 3)
    • <unit ID1>:<unit ID2>:..:<unit IDN> for multiple devices (for example, devices='0:1:3')
    • <unit ID1>-<unit IDN> for a range of devices (for example, devices='0-3')
    -1 (all GPU devices are used if the corresponding processing unit type is selected)
    Output settings
    logging_level

    The logging level to output to stdout.

    Possible values:
    • Silent — Do not output any logging information to stdout.

    • Verbose — Output the following data to stdout:

      • optimized metric
      • elapsed time of training
      • remaining time of training
    • Info — Output additional information and the number of trees.

    • Debug — Output debugging information.
    Verbose
    metric_period

    The frequency of iterations to calculate the values of objectives and metrics. The value should be a positive integer.

    The usage of this parameter speeds up the training.

    1
    verbose

    The frequency of iterations to print the information to stdout. The value of this parameter should be divisible by the value of the frequency of iterations to calculate the values of objectives and metrics.

    Restriction. Do not use this parameter with the logging_level parameter.
    1
    train_dir

    The directory for storing the files generated during training.

    catboost_info
    model_size_reg

    The model size regularization coefficient. The larger the value, the smaller the model size.

    Possible values are in the range .

    Large values reduce the number of feature combinations in the model. Note that the resulting quality of the model can be affected. Set the value to 0 to turn off the model size optimization option.

    0.5
    allow_writing_files

    Allow to write analytical and snapshot files during training.

    If set to “False”, the snapshot and data visualization tools are unavailable.

    TRUE
    save_snapshot

    Enable snapshotting for restoring the training progress after an interruption.

    None
    snapshot_fileThe name of the file to save the training progress information in. This file is used for recovering training after an interruption.
    Depending on whether the specified file exists in the file system:
    • Missing — Write information about training progress to the specified file.
    • Exists — Load data from the specified file and continue training from where it left off.
    File can't be generated or read. If the value is omitted, the file name is experiment.cbsnapshot.
    snapshot_interval

    The interval between saving snapshots in seconds.

    The first snapshot is taken after the specified number of seconds since the start of training. Every subsequent snapshot is taken after the specified number of seconds since the previous one. The last snapshot is taken at the end of the training.

    600
    CTR settings
    simple_ctr

    Binarization settings for simple categorical features.

    Format:

    c(CtrType[:TargetBorderCount=BorderCount][:TargetBorderType=BorderType][:CtrBorderCount=Count][:CtrBorderType=Type][:Prior=num_1/denum_1]..[:Prior=num_N/denum_N])
    Components:
    • CtrType — The method for transforming categorical features to numerical features.

      Supported methods for training on CPU:

      • Borders
      • Buckets
      • BinarizedTargetMeanValue
      • Counter

      Supported methods for training on GPU:

      • Borders
      • Buckets
      • FeatureFreq
      • FloatTargetMeanValue
    • TargetBorderCount — The number of borders for label value binarization. Only used for regression problems. Allowed values are integers from 1 to 255 inclusively. The default value is 1.

      This option is available for training on CPU only.

    • TargetBorderType — The binarization type for the label value. Only used for regression problems.

      Possible values:

      • Median
      • Uniform
      • UniformAndQuantiles
      • MaxLogSum
      • MinEntropy
      • GreedyLogSum

      By default, MinEntropy.

      This option is available for training on CPU only.

    • CtrBorderCount — The number of splits for categorical features. Allowed values are integers from 1 to 255 inclusively.
    • CtrBorderType — The binarization type for categorical features.

      Supported values for training on CPU:
      • Uniform

      Supported values for training on GPU:

      • Median
      • Uniform
      • UniformAndQuantiles
      • MaxLogSum
      • MinEntropy
      • GreedyLogSum
    • Prior — Use the specified priors during training (several values can be specified).

      Possible formats:
      • One number — Adds the value to the numerator.
      • Two slash-delimited numbers (for GPU only) — Use this format to set a fraction. The number is added to the numerator and the second is added to the denominator.
    combinations_ctr

    Binarization settings for combinations of categorical features.

    Format:

    c(CtrType[:TargetBorderCount=BorderCount][:TargetBorderType=BorderType][:CtrBorderCount=Count][:CtrBorderType=Type][:Prior=num_1/denum_1]..[:Prior=num_N/denum_N])
    Components:
    • CtrType — The method for transforming categorical features to numerical features.

      Supported methods for training on CPU:

      • Borders
      • Buckets
      • BinarizedTargetMeanValue
      • Counter

      Supported methods for training on GPU:

      • Borders
      • Buckets
      • FeatureFreq
      • FloatTargetMeanValue
    • TargetBorderCount — The number of borders for label value binarization. Only used for regression problems. Allowed values are integers from 1 to 255 inclusively. The default value is 1.

      This option is available for training on CPU only.

    • TargetBorderType — The binarization type for the label value. Only used for regression problems.

      Possible values:

      • Median
      • Uniform
      • UniformAndQuantiles
      • MaxLogSum
      • MinEntropy
      • GreedyLogSum

      By default, MinEntropy.

      This option is available for training on CPU only.

    • CtrBorderCount — The number of splits for categorical features. Allowed values are integers from 1 to 255 inclusively.
    • CtrBorderType — The binarization type for categorical features.

      Supported values for training on CPU:
      • Uniform
      Supported values for training on GPU:
      • Uniform
      • Median
    • Prior — Use the specified priors during training (several values can be specified).

      Possible formats:
      • One number — Adds the value to the numerator.
      • Two slash-delimited numbers (for GPU only) — Use this format to set a fraction. The number is added to the numerator and the second is added to the denominator.
    counter_calc_method

    The method for calculating the Counter CTR type.

    Possible values:
    • SkipTest — Objects from the validation dataset are not considered at all
    • Full — All objects from both learn and validation datasets are considered
    Full
    max_ctr_complexity

    The maximum number of categorical features that can be combined.

    4
    ctr_leaf_count_limit

    The maximum number of leaves with categorical features. If the quantity exceeds the specified value a part of leaves is discarded.

    The leaves to be discarded are selected as follows:

    1. The leaves are sorted by the frequency of the values.
    2. The top N leaves are selected, where N is the value specified in the parameter.
    3. All leaves starting from N+1 are discarded.

    This option reduces the resulting model size and the amount of memory required for training. Note that the resulting quality of the model can be affected.

    None

    The number of leafs with categorical features is not limited

    store_all_simple_ctr

    Ignore categorical features, which are not used in feature combinations, when choosing candidates for exclusion.

    Use this parameter with ctr_leaf_count_limit only.

    False

    Both simple features and feature combinations are taken in account when limiting the number of leafs with categorical features

    final_ctr_computation_mode

    Final CTR computation mode.

    Possible values:
    • Default — Compute final CTRs for learn and validation datasets.
    • Skip — Do not compute final CTRs for learn and validation datasets. In this case, the resulting model can not be applied. This mode decreases the size of the resulting model. It can be useful for research purposes when only the metric values have to be calculated.

    CPU and GPU