(l-onnx-doc-StringConcat)=

# StringConcat


(l-onnx-op-stringconcat-20)=

## StringConcat - 20

### Version

- **name**: [StringConcat (GitHub)](https://github.com/onnx/onnx/blob/main/docs/Operators.md#StringConcat)
- **domain**: `main`
- **since_version**: `20`
- **function**: `False`
- **support_level**: `SupportType.COMMON`
- **shape inference**: `True`

This version of the operator has been available
**since version 20**.

### Summary

StringConcat concatenates string tensors elementwise (with NumPy-style broadcasting support)

### Inputs

- **X** (heterogeneous) - **T**:

  Tensor to prepend in concatenation
- **Y** (heterogeneous) - **T**:

  Tensor to append in concatenation

### Outputs

- **Z** (heterogeneous) - **T**:

  Concatenated string tensor

### Type Constraints

* **T** in ( `tensor(string)` ):

  Inputs and outputs must be UTF-8 strings

### Examples

#### default

```python
import numpy as np
import onnx

node = onnx.helper.make_node(
    "StringConcat",
    inputs=["x", "y"],
    outputs=["result"],
)
x = np.array(["abc", "def"]).astype("object")
y = np.array([".com", ".net"]).astype("object")
result = np.array(["abc.com", "def.net"]).astype("object")

expect(node, inputs=[x, y], outputs=[result], name="test_string_concat")

x = np.array(["cat", "dog", "snake"]).astype("object")
y = np.array(["s"]).astype("object")
result = np.array(["cats", "dogs", "snakes"]).astype("object")

expect(
    node,
    inputs=[x, y],
    outputs=[result],
    name="test_string_concat_broadcasting",
)

x = np.array("cat").astype("object")
y = np.array("s").astype("object")
result = np.array("cats").astype("object")

expect(
    node,
    inputs=[x, y],
    outputs=[result],
    name="test_string_concat_zero_dimensional",
)

x = np.array(["abc", ""]).astype("object")
y = np.array(["", "abc"]).astype("object")
result = np.array(["abc", "abc"]).astype("object")

expect(
    node,
    inputs=[x, y],
    outputs=[result],
    name="test_string_concat_empty_string",
)

x = np.array(["的", "中"]).astype("object")
y = np.array(["的", "中"]).astype("object")
result = np.array(["的的", "中中"]).astype("object")

expect(
    node,
    inputs=[x, y],
    outputs=[result],
    name="test_string_concat_utf8",
)
```