Class RowIterator (2.33.0)

Version 2.33.0

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RowIterator(
    client,
    api_request,
    path,
    schema,
    page_token=None,
    max_results=None,
    page_size=None,
    extra_params=None,
    table=None,
    selected_fields=None,
    total_rows=None,
    first_page_response=None,
)

A class for iterating through HTTP/JSON API row list responses.

Parameters

Name	Description
client	Optional[google.cloud.bigquery.Client] The API client instance. This should always be non-None, except for subclasses that do not use it, namely the _EmptyRowIterator.
api_request	Callable[google.cloud._http.JSONConnection.api_request] The function to use to make API requests.
path	str The method path to query for the list of items.
schema	Sequence[Union[ SchemaField, Mapping[str, Any] ]] The table's schema. If any item is a mapping, its content must be compatible with from_api_repr.
page_token	str A token identifying a page in a result set to start fetching results from.
max_results	Optional[int] The maximum number of results to fetch.
page_size	Optional[int] The maximum number of rows in each page of results from this request. Non-positive values are ignored. Defaults to a sensible value set by the API.
extra_params	Optional[Dict[str, object]] Extra query string parameters for the API call.
table	Optional[Union[ google.cloud.bigquery.table.Table, google.cloud.bigquery.table.TableReference, ]] The table which these rows belong to, or a reference to it. Used to call the BigQuery Storage API to fetch rows.
selected_fields	Optional[Sequence[google.cloud.bigquery.schema.SchemaField]] A subset of columns to select from this table.
total_rows	Optional[int] Total number of rows in the table.
first_page_response	Optional[dict] API response for the first page of results. These are returned when the first page is requested.

Inheritance

builtins.object > google.api_core.page_iterator.Iterator > google.api_core.page_iterator.HTTPIterator > RowIterator

Properties

pages

Iterator of pages in the response.

Exceptions

Type	Description
ValueError	If the iterator has already been started.

Returns

Type	Description
types.GeneratorType[google.api_core.page_iterator.Page]	A generator of page instances.

schema

List[google.cloud.bigquery.schema.SchemaField]: The subset of columns to be read from the table.

total_rows

int: The total number of rows in the table.

Methods

__iter__

__iter__()

Iterator for each item returned.

Exceptions

Type	Description
ValueError	If the iterator has already been started.

Returns

Type	Description
types.GeneratorType[Any]	A generator of items from the API.

to_arrow

to_arrow(
    progress_bar_type: str = None,
    bqstorage_client: bigquery_storage.BigQueryReadClient = None,
    create_bqstorage_client: bool = True,
)

[Beta] Create a class:pyarrow.Table by loading all pages of a table or query.

Parameters

Name	Description
progress_bar_type	Optional[str] If set, use the tqdm <https://tqdm.github.io/>_ library to display a progress bar while the data downloads. Install the tqdm package to use this feature. Possible values of progress_bar_type include: None No progress bar. 'tqdm' Use the tqdm.tqdm function to print a progress bar to :data:sys.stderr. 'tqdm_notebook' Use the tqdm.tqdm_notebook function to display a progress bar as a Jupyter notebook widget. 'tqdm_gui' Use the tqdm.tqdm_gui function to display a progress bar as a graphical dialog box.
create_bqstorage_client	Optional[bool] If True (default), create a BigQuery Storage API client using the default API settings. The BigQuery Storage API is a faster way to fetch rows from BigQuery. See the bqstorage_client parameter for more information. This argument does nothing if bqstorage_client is supplied. .. versionadded:: 1.24.0
bqstorage_client	Optional[google.cloud.bigquery_storage_v1.BigQueryReadClient] A BigQuery Storage API client. If supplied, use the faster BigQuery Storage API to fetch rows from BigQuery. This API is a billable API. This method requires the pyarrow and google-cloud-bigquery-storage libraries. This method only exposes a subset of the capabilities of the BigQuery Storage API. For full access to all features (projections, filters, snapshots) use the Storage API directly.

Exceptions

Type	Description
ValueError	If the `pyarrow` library cannot be imported. .. versionadded:: 1.17.0

to_arrow_iterable

to_arrow_iterable(bqstorage_client: bigquery_storage.BigQueryReadClient = None, max_queue_size: int = <object object>)

[Beta] Create an iterable of class:pyarrow.RecordBatch, to process the table as a stream.

Parameters

Name	Description
max_queue_size	Optional[int] The maximum number of result pages to hold in the internal queue when streaming query results over the BigQuery Storage API. Ignored if Storage API is not used. By default, the max queue size is set to the number of BQ Storage streams created by the server. If max_queue_size is :data:None, the queue size is infinite.
bqstorage_client	Optional[google.cloud.bigquery_storage_v1.BigQueryReadClient] A BigQuery Storage API client. If supplied, use the faster BigQuery Storage API to fetch rows from BigQuery. This method requires the pyarrow and google-cloud-bigquery-storage libraries. This method only exposes a subset of the capabilities of the BigQuery Storage API. For full access to all features (projections, filters, snapshots) use the Storage API directly.

Exceptions

Type	Description
ValueError	If the `pyarrow` library cannot be imported. .. versionadded:: 2.31.0

Returns

Type	Description
pyarrow.RecordBatch	A generator of `pyarrow.RecordBatch`.

to_dataframe

to_dataframe(
    bqstorage_client: bigquery_storage.BigQueryReadClient = None,
    dtypes: Dict[str, Any] = None,
    progress_bar_type: str = None,
    create_bqstorage_client: bool = True,
    date_as_object: bool = True,
    geography_as_object: bool = False,
)

Create a pandas DataFrame by loading all pages of a query.

Parameters

Name	Description
dtypes	Optional[Map[str, Union[str, pandas.Series.dtype]]] A dictionary of column names pandas dtypes. The provided dtype is used when constructing the series for the column specified. Otherwise, the default pandas behavior is used.
progress_bar_type	Optional[str] If set, use the tqdm <https://tqdm.github.io/>_ library to display a progress bar while the data downloads. Install the tqdm package to use this feature. Possible values of progress_bar_type include: None No progress bar. 'tqdm' Use the tqdm.tqdm function to print a progress bar to :data:sys.stderr. 'tqdm_notebook' Use the tqdm.tqdm_notebook function to display a progress bar as a Jupyter notebook widget. 'tqdm_gui' Use the tqdm.tqdm_gui function to display a progress bar as a graphical dialog box. .. versionadded:: 1.11.0
create_bqstorage_client	Optional[bool] If True (default), create a BigQuery Storage API client using the default API settings. The BigQuery Storage API is a faster way to fetch rows from BigQuery. See the bqstorage_client parameter for more information. This argument does nothing if bqstorage_client is supplied. .. versionadded:: 1.24.0
date_as_object	Optional[bool] If True (default), cast dates to objects. If False, convert to datetime64[ns] dtype. .. versionadded:: 1.26.0
geography_as_object	Optional[bool] If True, convert GEOGRAPHY data to shapely geometry objects. If False (default), don't cast geography data to shapely geometry objects. .. versionadded:: 2.24.0
bqstorage_client	Optional[google.cloud.bigquery_storage_v1.BigQueryReadClient] A BigQuery Storage API client. If supplied, use the faster BigQuery Storage API to fetch rows from BigQuery. This method requires the pyarrow and google-cloud-bigquery-storage libraries. This method only exposes a subset of the capabilities of the BigQuery Storage API. For full access to all features (projections, filters, snapshots) use the Storage API directly.

Exceptions

Type	Description
ValueError	If the `pandas` library cannot be imported, or the bigquery_storage_v1 module is required but cannot be imported. Also if `geography_as_object` is `True`, but the `shapely` library cannot be imported.

Returns

Type	Description
pandas.DataFrame	A `pandas.DataFrame` populated with row data and column headers from the query results. The column headers are derived from the destination table's schema.

to_dataframe_iterable

to_dataframe_iterable(bqstorage_client: bigquery_storage.BigQueryReadClient = None, dtypes: Dict[str, Any] = None, max_queue_size: int = <object object>)

Create an iterable of pandas DataFrames, to process the table as a stream.

Parameters

Name	Description
dtypes	Optional[Map[str, Union[str, pandas.Series.dtype]]] A dictionary of column names pandas dtypes. The provided dtype is used when constructing the series for the column specified. Otherwise, the default pandas behavior is used.
max_queue_size	Optional[int] The maximum number of result pages to hold in the internal queue when streaming query results over the BigQuery Storage API. Ignored if Storage API is not used. By default, the max queue size is set to the number of BQ Storage streams created by the server. If max_queue_size is :data:None, the queue size is infinite. .. versionadded:: 2.14.0
bqstorage_client	Optional[google.cloud.bigquery_storage_v1.BigQueryReadClient] A BigQuery Storage API client. If supplied, use the faster BigQuery Storage API to fetch rows from BigQuery. This method requires the pyarrow and google-cloud-bigquery-storage libraries. This method only exposes a subset of the capabilities of the BigQuery Storage API. For full access to all features (projections, filters, snapshots) use the Storage API directly.

Exceptions

Type	Description
ValueError	If the `pandas` library cannot be imported.

Returns

Type	Description
pandas.DataFrame	A generator of `pandas.DataFrame`.

to_geodataframe

to_geodataframe(
    bqstorage_client: bigquery_storage.BigQueryReadClient = None,
    dtypes: Dict[str, Any] = None,
    progress_bar_type: str = None,
    create_bqstorage_client: bool = True,
    date_as_object: bool = True,
    geography_column: Optional[str] = None,
)

Create a GeoPandas GeoDataFrame by loading all pages of a query.

Parameters

Name	Description
dtypes	Optional[Map[str, Union[str, pandas.Series.dtype]]] A dictionary of column names pandas dtypes. The provided dtype is used when constructing the series for the column specified. Otherwise, the default pandas behavior is used.
progress_bar_type	Optional[str] If set, use the tqdm <https://tqdm.github.io/>_ library to display a progress bar while the data downloads. Install the tqdm package to use this feature. Possible values of progress_bar_type include: None No progress bar. 'tqdm' Use the tqdm.tqdm function to print a progress bar to :data:sys.stderr. 'tqdm_notebook' Use the tqdm.tqdm_notebook function to display a progress bar as a Jupyter notebook widget. 'tqdm_gui' Use the tqdm.tqdm_gui function to display a progress bar as a graphical dialog box.
create_bqstorage_client	Optional[bool] If True (default), create a BigQuery Storage API client using the default API settings. The BigQuery Storage API is a faster way to fetch rows from BigQuery. See the bqstorage_client parameter for more information. This argument does nothing if bqstorage_client is supplied.
date_as_object	Optional[bool] If True (default), cast dates to objects. If False, convert to datetime64[ns] dtype.
geography_column	Optional[str] If there are more than one GEOGRAPHY column, identifies which one to use to construct a geopandas GeoDataFrame. This option can be ommitted if there's only one GEOGRAPHY column.
bqstorage_client	Optional[google.cloud.bigquery_storage_v1.BigQueryReadClient] A BigQuery Storage API client. If supplied, use the faster BigQuery Storage API to fetch rows from BigQuery. This method requires the pyarrow and google-cloud-bigquery-storage libraries. This method only exposes a subset of the capabilities of the BigQuery Storage API. For full access to all features (projections, filters, snapshots) use the Storage API directly.

Exceptions

Type	Description
ValueError	If the `geopandas` library cannot be imported, or the bigquery_storage_v1 module is required but cannot be imported. .. versionadded:: 2.24.0

Returns

Type	Description
geopandas.GeoDataFrame	A `geopandas.GeoDataFrame` populated with row data and column headers from the query results. The column headers are derived from the destination table's schema.

__init__

__init__(
    client,
    api_request,
    path,
    schema,
    page_token=None,
    max_results=None,
    page_size=None,
    extra_params=None,
    table=None,
    selected_fields=None,
    total_rows=None,
    first_page_response=None,
)

Initialize self. See help(type(self)) for accurate signature.

RowIterator

RowIterator(
    client,
    api_request,
    path,
    schema,
    page_token=None,
    max_results=None,
    page_size=None,
    extra_params=None,
    table=None,
    selected_fields=None,
    total_rows=None,
    first_page_response=None,
)

A class for iterating through HTTP/JSON API row list responses.

Parameters

Name	Description
client	Optional[google.cloud.bigquery.Client] The API client instance. This should always be non-None, except for subclasses that do not use it, namely the _EmptyRowIterator.
api_request	Callable[google.cloud._http.JSONConnection.api_request] The function to use to make API requests.
path	str The method path to query for the list of items.
schema	Sequence[Union[ SchemaField, Mapping[str, Any] ]] The table's schema. If any item is a mapping, its content must be compatible with from_api_repr.
page_token	str A token identifying a page in a result set to start fetching results from.
max_results	Optional[int] The maximum number of results to fetch.
page_size	Optional[int] The maximum number of rows in each page of results from this request. Non-positive values are ignored. Defaults to a sensible value set by the API.
extra_params	Optional[Dict[str, object]] Extra query string parameters for the API call.
table	Optional[Union[ google.cloud.bigquery.table.Table, google.cloud.bigquery.table.TableReference, ]] The table which these rows belong to, or a reference to it. Used to call the BigQuery Storage API to fetch rows.
selected_fields	Optional[Sequence[google.cloud.bigquery.schema.SchemaField]] A subset of columns to select from this table.
total_rows	Optional[int] Total number of rows in the table.
first_page_response	Optional[dict] API response for the first page of results. These are returned when the first page is requested.