rx_get_info

Article
07/15/2019

Usage

revoscalepy.rx_get_info(data, get_var_info: bool = False,
    get_block_sizes: bool = False, get_value_labels: bool = None,
    vars_to_keep: list = None, vars_to_drop: list = None,
    start_row: int = 1, num_rows: int = 0,
    compute_info: bool = False, all_nodes: bool = False,
    verbose: int = 0)

Description

Get basic information about a revoscalepy data source or data frame.

Arguments

data

A data frame, a character string specifying an “.xdf”, or an RxDataSource object. If a local compute context is being used, this argument may also be a list of data sources, in which case the output will be returned in a named list. See the details section for more information. If a Spark compute context is being used, this argument may also be an RxHiveData, RxOrcData, RxParquetData or RxSparkDataFrame object or a Spark data frame object from pyspark.sql.DataFrame.

get_var_info

Bool value. If True, variable information is returned.

get_block_sizes

Bool value. If True, block sizes are returned in the output for an “.xdf” file, and when printed the first 10 block sizes are shown.

get_value_labels

Bool value. If True and get_var_info is True or None, factor value labels are included in the output.

vars_to_keep

List of strings of variable names for which information is returned. If None or get_var_info is False, argument is ignored. Cannot be used with vars_to_drop.

vars_to_drop

List of strings of variable names for which information is not returned. If None or get_var_info is False, argument is ignored. Cannot be used with vars_to_keep.

start_row

Starting row for retrieval of data of a data frame or “.xdf” file.

num_rows

Number of rows of data to retrieve of a data frame or “.xdf” file.

compute_info

Bool value. If True, and get_var_info is True, variable information (e.g., high/low values) for non-xdf data sources will be computed by reading through the data set. If True, and get_var_info is False, the number of variables will be gotten from non-xdf data sources (but not the number of rows).

all_nodes

Bool value. Ignored if the active RxComputeContext compute context is local or RxForeachDoPar. Otherwise, if True, a list containing the information for the data set on each node in the active compute context will be returned. If False, only information on the data set on the master node will be returned. Note that the determination of the master node is not controlled by the end user.

verbose

Integer value. If 0, no additional output is printed. If 1, additional summary information is printed for an “.xdf” file.

Returns

List containing the following possible elements:

fileName: Character string containing the file name and path (if an
    ”.xdf” file).

objName: Character string containing object name (if not an “.xdf” file).
class: Class of the object.
length: Length of the object if it is not an “.xdf” file or data frame.
numCompositeFiles: Number of composite data files(if a composite “.xdf” file).

numRows: Number of rows in the data set.
numVars: Number of variables in the data set.
numBlocks: Number of blocks in the data set.
varInfo: List of variable information where each element is a list

    describing a variable.

rowsPerBlock: Integer vector containing number of rows in each block
    (if get_block_sizes is set to True). Set to None if data is a data frame.

data: Data frame containing the data (if num_rows > 0)

Example

import os
from revoscalepy import RxOptions, RxXdfData, rx_get_info

sample_data_path = RxOptions.get_option("sampleDataDir")
claims_ds = RxXdfData(os.path.join(sample_data_path, "claims.xdf"))
info = rx_get_info(claims_ds, get_var_info=True)
print(info)

Output:

File name:C:\swarm\workspace\bigAnalytics-9.4.0\python\revoscalepy\revoscalepy\data\sample_data\claims.xdf
Number of observations:128.0
Number of variables:6.0
Number of blocks:1.0
Compression type:zlib
Variable information: 
Var 1: RowNum, Type: integer, Storage: int32, Low/High: (1.0000, 128.0000)
Var 2: age
	8 factor levels: ['17-20', '21-24', '25-29', '30-34', '35-39', '40-49', '50-59', '60+']
Var 3: car.age
	4 factor levels: ['0-3', '4-7', '8-9', '10+']
Var 4: type
	4 factor levels: ['A', 'B', 'C', 'D']
Var 5: cost, Type: numeric, Storage: float32, Low/High: (11.0000, 850.0000)
Var 6: number, Type: numeric, Storage: float32, Low/High: (0.0000, 434.0000)

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