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ToString

Pydoc

Transforms every element in an input collection to a string.

Setup

To run a code cell, you can click the Run cell button at the top left of the cell, or select it and press Shift+Enter. Try modifying a code cell and re-running it to see what happens.

To learn more about Colab, see Welcome to Colaboratory!.

First, let's install the apache-beam module.



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!pip install --quiet -U apache-beam

Examples

Any non-string element can be converted to a string using standard Python functions and methods. Many I/O transforms, such as textio.WriteToText, expect their input elements to be strings.

Example 1: Key-value pairs to string

The following example converts a (key, value) pair into a string delimited by ','. You can specify a different delimiter using the delimiter argument.



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import apache_beam as beam

with beam.Pipeline() as pipeline:
  plants = (
      pipeline
      | 'Garden plants' >> beam.Create([
          ('🍓', 'Strawberry'),
          ('🥕', 'Carrot'),
          ('🍆', 'Eggplant'),
          ('🍅', 'Tomato'),
          ('🥔', 'Potato'),
      ])
      | 'To string' >> beam.ToString.Kvs()
      | beam.Map(print)
  )

View source code

Example 2: Elements to string

The following example converts a dictionary into a string. The string output will be equivalent to str(element).



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import apache_beam as beam

with beam.Pipeline() as pipeline:
  plant_lists = (
      pipeline
      | 'Garden plants' >> beam.Create([
          ['🍓', 'Strawberry', 'perennial'],
          ['🥕', 'Carrot', 'biennial'],
          ['🍆', 'Eggplant', 'perennial'],
          ['🍅', 'Tomato', 'annual'],
          ['🥔', 'Potato', 'perennial'],
      ])
      | 'To string' >> beam.ToString.Element()
      | beam.Map(print)
  )

View source code

Example 3: Iterables to string

The following example converts an iterable, in this case a list of strings, into a string delimited by ','. You can specify a different delimiter using the delimiter argument. The string output will be equivalent to iterable.join(delimiter).



In [ ]:

    
import apache_beam as beam

with beam.Pipeline() as pipeline:
  plants_csv = (
      pipeline
      | 'Garden plants' >> beam.Create([
          ['🍓', 'Strawberry', 'perennial'],
          ['🥕', 'Carrot', 'biennial'],
          ['🍆', 'Eggplant', 'perennial'],
          ['🍅', 'Tomato', 'annual'],
          ['🥔', 'Potato', 'perennial'],
      ])
      | 'To string' >> beam.ToString.Iterables()
      | beam.Map(print)
  )

View source code

Map applies a simple 1-to-1 mapping function over each element in the collection

Pydoc

View the docs

ToString

Setup

Examples

Example 1: Key-value pairs to string

Example 2: Elements to string

Example 3: Iterables to string

Related transforms