Add pad transform

1 files changed, 20 insertions, 0 deletions

diff --git a/text_recognizer/data/transforms/pad.py b/text_recognizer/data/transforms/pad.py
new file mode 100644
index 0000000..82e4d54
--- /dev/null
+++ b/text_recognizer/data/transforms/pad.py
@@ -0,0 +1,20 @@
+"""Pad targets to equal length."""
+
+import torch
+from torch import Tensor
+import torch.functional as F
+
+
+class Pad:
+    """Pad target sequence."""
+
+    def __init__(self, max_len: int, pad_index: int) -> None:
+        self.max_len = max_len
+        self.pad_index = pad_index
+
+    def __call__(self, y: Tensor) -> Tensor:
+        """Pads sequences with pad index if shorter than max len."""
+        if y.shape[-1] < self.length:
+            pad_len = self.max_len - len(y)
+            y = torch.cat((y, torch.LongTensor([self.pad_index] * pad_len)))
+        return y[: self.max_len]