---
title: "ToString"
---
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# ToString

{{< localstorage language language-py >}}

{{< button-pydoc path="apache_beam.transforms.util" class="ToString" >}}

Transforms every element in an input collection to a string.

## 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`](https://beam.apache.org/releases/pydoc/current/apache_beam.io.textio.html#apache_beam.io.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.

{{< highlight py >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py" tostring_kvs >}}
{{< /highlight >}}

{{< paragraph class="notebook-skip" >}}
Output `PCollection` after `ToString`:
{{< /paragraph >}}

{{< highlight class="notebook-skip" >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring_test.py" plants >}}
{{< /highlight >}}

{{< buttons-code-snippet
  py="sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py"
  notebook="examples/notebooks/documentation/transforms/python/elementwise/tostring" >}}

### Example 2: Elements to string

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

{{< highlight py >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py" tostring_element >}}
{{< /highlight >}}

{{< paragraph class="notebook-skip" >}}
Output `PCollection` after `ToString`:
{{< /paragraph >}}

{{< highlight class="notebook-skip" >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring_test.py" plant_lists >}}
{{< /highlight >}}

{{< buttons-code-snippet
  py="sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py"
  notebook="examples/notebooks/documentation/transforms/python/elementwise/tostring" >}}

### 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)`.

{{< highlight py >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py" tostring_iterables >}}
{{< /highlight >}}

{{< paragraph class="notebook-skip" >}}
Output `PCollection` after `ToString`:
{{< /paragraph >}}

{{< highlight class="notebook-skip" >}}
{{< code_sample "sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring_test.py" plants_csv >}}
{{< /highlight >}}

{{< buttons-code-snippet
  py="sdks/python/apache_beam/examples/snippets/transforms/elementwise/tostring.py"
  notebook="examples/notebooks/documentation/transforms/python/elementwise/tostring" >}}

## Related transforms

* [Map](/documentation/transforms/python/elementwise/map) applies a simple 1-to-1 mapping function over each element in the collection

{{< button-pydoc path="apache_beam.transforms.util" class="ToString" >}}
