Teradata Package for Python Function Reference on VantageCloud Lake - fastexport - Teradata Package for Python - Look here for syntax, methods and examples for the functions included in the Teradata Package for Python.
Teradata® Package for Python Function Reference on VantageCloud Lake
- Deployment
- VantageCloud
- Edition
- Lake
- Product
- Teradata Package for Python
- Release Number
- 20.00.00.02
- Published
- September 2024
- Language
- English (United States)
- Last Update
- 2024-10-17
- dita:id
- TeradataPython_FxRef_Lake_2000
- Product Category
- Teradata Vantage
- teradataml.dataframe.data_transfer.fastexport = fastexport(df, export_to='pandas', index_column=None, catch_errors_warnings=False, csv_file=None, **kwargs)
- DESCRIPTION:
The fastexport() API exports teradataml DataFrame to Pandas DataFrame
or CSV file using FastExport data transfer protocol.
Note:
1. Teradata recommends to use FastExport when number of rows in
teradataml DataFrame are at least 100,000. To extract lesser rows
ignore this function and go with regular to_pandas() or to_csv()
function. FastExport opens multiple data transfer connections to the
database.
2. FastExport does not support all Teradata Database data types.
For example, tables with BLOB and CLOB type columns cannot
be extracted.
3. FastExport cannot be used to extract data from a volatile or
temporary table.
4. For best efficiency, do not use DataFrame.groupby() and
DataFrame.sort() with FastExport.
For additional information about FastExport protocol through
teradatasql driver, please refer to FASTEXPORT section of
https://pypi.org/project/teradatasql/#FastExport driver documentation.
PARAMETERS:
df:
Required Argument.
Specifies teradataml DataFrame that needs to be exported.
Types: teradataml DataFrame
export_to:
Optional Argument.
Specifies a value that notifies where to export the data.
Permitted Values:
* "pandas": Export data to a Pandas DataFrame.
* "csv": Export data to a given CSV file.
Default Value: "pandas"
Types: String
index_column:
Optional Argument.
Specifies column(s) to be used as index column for the converted object.
Note:
Applicable only when 'export_to' is set to "pandas".
Default Value: None.
Types: String OR list of Strings (str)
catch_errors_warnings:
Optional Argument.
Specifies whether to catch errors/warnings(if any) raised by
fastexport protocol while converting teradataml DataFrame.
Notes :
1. When 'export_to' is set to "pandas" and 'catch_errors_warnings' is set to True,
fastexport() returns a tuple containing:
a. Pandas DataFrame.
b. Errors(if any) in a list thrown by fastexport.
c. Warnings(if any) in a list thrown by fastexport.
When set to False, prints the fastexport errors/warnings to the
standard output, if there are any.
2. When 'export_to' is set to "csv" and 'catch_errors_warnings' is set to True,
fastexport() returns a tuple containing:
a. Errors(if any) in a list thrown by fastexport.
b. Warnings(if any) in a list thrown by fastexport.
Default Value: False
Types: bool
csv_file:
Optional Argument.
Specifies the name of CSV file to which data is to be exported.
Note:
This is required argument when 'export_to' is set to "csv".
Types: String
kwargs:
Optional Argument.
Specifies keyword arguments. Accepts following keyword arguments:
sep:
Optional Argument.
Specifies a single character string used to separate fields in a CSV file.
Default Value: ","
Notes:
1. "sep" cannot be line feed ('\n') or carriage return ('\r').
2. "sep" should not be same as "quotechar".
3. Length of "sep" argument should be 1.
Types: String
quotechar:
Optional Argument.
Specifies a single character string used to quote fields in a CSV file.
Default Value: """
Notes:
1. "quotechar" cannot be line feed ('\n') or carriage return ('\r').
2. "quotechar" should not be same as "sep".
3. Length of "quotechar" argument should be 1.
Types: String
coerce_float:
Optional Argument.
Specifies whether to convert non-string, non-numeric objects to floating point.
Note:
For additional information about "coerce_float" please refer to:
https://pandas.pydata.org/docs/reference/api/pandas.read_sql.html
parse_dates:
Optional Argument.
Specifies columns to parse as dates.
Note:
For additional information about "parse_date" please refer to:
https://pandas.pydata.org/docs/reference/api/pandas.read_sql.html
open_sessions:
Optional Argument.
specifies the number of Teradata sessions to be opened for fastexport.
Note:
If "open_sessions" argument is not provided, the default value
is the smaller of 8 or the number of AMPs avaialble.
For additional information about number of Teradata data-transfer
sessions opened during fastexport, please refer to:
https://pypi.org/project/teradatasql/#FastExport
Types: Integer
RETURNS:
1. When 'export_to' is set to "pandas" and "catch_errors_warnings" is set to True,
then the function returns a tuple containing:
a. Pandas DataFrame.
b. Errors, if any, thrown by fastexport in a list of strings.
c. Warnings, if any, thrown by fastexport in a list of strings.
When 'export_to' is set to "pandas" and "catch_errors_warnings" is set to False,
then the function returns a Pandas DataFrame.
2. When 'export_to' is set to "csv" and "catch_errors_warnings" is set to True,
then the function returns a tuple containing:
a. Errors, if any, thrown by fastexport in a list of strings.
b. Warnings, if any, thrown by fastexport in a list of strings.
EXAMPLES:
>>> from teradataml import *
>>> load_example_data("dataframe", "admissions_train")
>>> df = DataFrame("admissions_train")
# Print dataframe.
>>> df
masters gpa stats programming admitted
id
13 no 4.00 Advanced Novice 1
26 yes 3.57 Advanced Advanced 1
5 no 3.44 Novice Novice 0
19 yes 1.98 Advanced Advanced 0
15 yes 4.00 Advanced Advanced 1
40 yes 3.95 Novice Beginner 0
7 yes 2.33 Novice Novice 1
22 yes 3.46 Novice Beginner 0
36 no 3.00 Advanced Novice 0
38 yes 2.65 Advanced Beginner 1
# Example 1: Export teradataml DataFrame df to Pandas DataFrame using
# fastexport().
>>> fastexport(df)
Errors: []
Warnings: []
masters gpa stats programming admitted
id
38 yes 2.65 Advanced Beginner 1
26 yes 3.57 Advanced Advanced 1
5 no 3.44 Novice Novice 0
24 no 1.87 Advanced Novice 1
3 no 3.70 Novice Beginner 1
1 yes 3.95 Beginner Beginner 0
20 yes 3.90 Advanced Advanced 1
18 yes 3.81 Advanced Advanced 1
8 no 3.60 Beginner Advanced 1
25 no 3.96 Advanced Advanced 1
...
# Example 2: Export teradataml DataFrame df to Pandas DataFrame,
# set index column, coerce_float and catch errors/warnings thrown by
# fastexport.
>>> pandas_df, err, warn = fastexport(df, index_column="gpa",
catch_errors_warnings=True,
coerce_float=True)
# Print pandas DataFrame.
>>> pandas_df
id masters stats programming admitted
gpa
2.65 38 yes Advanced Beginner 1
3.57 26 yes Advanced Advanced 1
3.44 5 no Novice Novice 0
1.87 24 no Advanced Novice 1
3.70 3 no Novice Beginner 1
3.95 1 yes Beginner Beginner 0
3.90 20 yes Advanced Advanced 1
3.81 18 yes Advanced Advanced 1
3.60 8 no Beginner Advanced 1
3.96 25 no Advanced Advanced 1
3.76 2 yes Beginner Beginner 0
3.83 17 no Advanced Advanced 1
...
# Print errors list.
>>> err
[]
# Print warnings list.
>>> warn
[]
# Example 3: Following example exports teradataml DataFrame df
# to Pandas DataFrame using fastexport() by opening specified
# number of Teradata data-transfer sessions.
>>> fastexport(df, open_sessions=2)
Errors: []
Warnings: []
masters gpa stats programming admitted
id
38 yes 2.65 Advanced Beginner 1
26 yes 3.57 Advanced Advanced 1
5 no 3.44 Novice Novice 0
24 no 1.87 Advanced Novice 1
3 no 3.70 Novice Beginner 1
1 yes 3.95 Beginner Beginner 0
20 yes 3.90 Advanced Advanced 1
18 yes 3.81 Advanced Advanced 1
8 no 3.60 Beginner Advanced 1
25 no 3.96 Advanced Advanced 1
...
# Example 4: Following example exports teradataml DataFrame df
# to a given CSV file using fastexport().
>>> fastexport(df, export_to="csv", csv_file="Test.csv")
Data is successfully exported into Test.csv
# Example 5: Following example exports teradataml DataFrame df
# to a given CSV file using fastexport() by opening specified
# number of Teradata data-transfer sessions.
>>> fastexport(df, export_to="csv", csv_file="Test_1.csv", open_sessions=2)
Data is successfully exported into Test_1.csv
# Example 6: Following example exports teradataml DataFrame df
# to a given CSV file using fastexport() and catch errors/warnings
# thrown by fastexport.
>>> err, warn = fastexport(df, export_to="csv", catch_errors_warnings=True,
csv_file="Test_3.csv")
Data is successfully exported into Test_3.csv
# Print errors list.
>>> err
[]
# Print warnings list.
>>> warn
[]
# Example 7: Export teradataml DataFrame to CSV file with '|' as field separator
# and single quote(') as field quote character.
>>> fastexport(df, export_to="csv", csv_file="Test_4.csv", sep = "|", quotechar="'")
Data is successfully exported into Test_4.csv