make_csv_dataset: Reads CSV files into a batched dataset

In tfdatasets: Interface to 'TensorFlow' Datasets

Reads CSV files into a batched dataset

Description

Reads CSV files into a dataset, where each element is a (features, labels) list that corresponds to a batch of CSV rows. The features dictionary maps feature column names to tensors containing the corresponding feature data, and labels is a tensor containing the batch's label data.

Usage

make_csv_dataset(
  file_pattern,
  batch_size,
  column_names = NULL,
  column_defaults = NULL,
  label_name = NULL,
  select_columns = NULL,
  field_delim = ",",
  use_quote_delim = TRUE,
  na_value = "",
  header = TRUE,
  num_epochs = NULL,
  shuffle = TRUE,
  shuffle_buffer_size = 10000,
  shuffle_seed = NULL,
  prefetch_buffer_size = 1,
  num_parallel_reads = 1,
  num_parallel_parser_calls = 2,
  sloppy = FALSE,
  num_rows_for_inference = 100
)

Arguments

file_pattern	List of files or glob patterns of file paths containing CSV records.
batch_size	An integer representing the number of records to combine in a single batch.
column_names	An optional list of strings that corresponds to the CSV columns, in order. One per column of the input record. If this is not provided, infers the column names from the first row of the records. These names will be the keys of the features dict of each dataset element.
column_defaults	A optional list of default values for the CSV fields. One item per selected column of the input record. Each item in the list is either a valid CSV dtype (integer, numeric, or string), or a tensor with one of the aforementioned types. The tensor can either be a scalar default value (if the column is optional), or an empty tensor (if the column is required). If a dtype is provided instead of a tensor, the column is also treated as required. If this list is not provided, tries to infer types based on reading the first num_rows_for_inference rows of files specified, and assumes all columns are optional, defaulting to 0 for numeric values and "" for string values. If both this and select_columns are specified, these must have the same lengths, and column_defaults is assumed to be sorted in order of increasing column index.
label_name	A optional string corresponding to the label column. If provided, the data for this column is returned as a separate tensor from the features dictionary, so that the dataset complies with the format expected by a TF Estiamtors and Keras.
select_columns	(Ignored if using TensorFlow version 1.8.) An optional list of integer indices or string column names, that specifies a subset of columns of CSV data to select. If column names are provided, these must correspond to names provided in column_names or inferred from the file header lines. When this argument is specified, only a subset of CSV columns will be parsed and returned, corresponding to the columns specified. Using this results in faster parsing and lower memory usage. If both this and column_defaults are specified, these must have the same lengths, and column_defaults is assumed to be sorted in order of increasing column index.
field_delim	An optional string. Defaults to ",". Char delimiter to separate fields in a record.
use_quote_delim	An optional bool. Defaults to TRUE. If false, treats double quotation marks as regular characters inside of the string fields.
na_value	Additional string to recognize as NA/NaN.
header	A bool that indicates whether the first rows of provided CSV files correspond to header lines with column names, and should not be included in the data.
num_epochs	An integer specifying the number of times this dataset is repeated. If NULL, cycles through the dataset forever.
shuffle	A bool that indicates whether the input should be shuffled.
shuffle_buffer_size	Buffer size to use for shuffling. A large buffer size ensures better shuffling, but increases memory usage and startup time.
shuffle_seed	Randomization seed to use for shuffling.
prefetch_buffer_size	An int specifying the number of feature batches to prefetch for performance improvement. Recommended value is the number of batches consumed per training step.
num_parallel_reads	Number of threads used to read CSV records from files. If >1, the results will be interleaved.
num_parallel_parser_calls	(Ignored if using TensorFlow version 1.11 or later.) Number of parallel invocations of the CSV parsing function on CSV records.
sloppy	If TRUE, reading performance will be improved at the cost of non-deterministic ordering. If FALSE, the order of elements produced is deterministic prior to shuffling (elements are still randomized if shuffle=TRUE. Note that if the seed is set, then order of elements after shuffling is deterministic). Defaults to FALSE.
num_rows_for_inference	Number of rows of a file to use for type inference if record_defaults is not provided. If NULL, reads all the rows of all the files. Defaults to 100.

Value

A dataset, where each element is a (features, labels) list that corresponds to a batch of batch_size CSV rows. The features dictionary maps feature column names to tensors containing the corresponding column data, and labels is a tensor containing the column data for the label column specified by label_name.

tfdatasets documentation built on Sept. 11, 2024, 8:53 p.m.