ARROW-9247: [Python] Expose total_values_length functions on BinaryArray, LargeBinaryArray

python/pyarrow/array.pxi

@@ -1789,12 +1789,26 @@ cdef class BinaryArray(Array):
     """
     Concrete class for Arrow arrays of variable-sized binary data type.
     """
+    @property
+    def total_values_length(self):
+        """
+        The number of bytes from beginning to end of the data buffer addressed
+        by the offsets of this BinaryArray.
+        """
+        return (<CBinaryArray*> self.ap).total_values_length()
 
 
 cdef class LargeBinaryArray(Array):
     """
     Concrete class for Arrow arrays of large variable-sized binary data type.
     """
+    @property
+    def total_values_length(self):
+        """
+        The number of bytes from beginning to end of the data buffer addressed
+        by the offsets of this LargeBinaryArray.
+        """
+        return (<CLargeBinaryArray*> self.ap).total_values_length()
 
 
 cdef class DictionaryArray(Array):

python/pyarrow/includes/libarrow.pxd

@@ -593,12 +593,14 @@ cdef extern from "arrow/api.h" namespace "arrow" nogil:
         shared_ptr[CBuffer] value_data()
         int32_t value_offset(int64_t i)
         int32_t value_length(int64_t i)
+        int32_t total_values_length()
 
     cdef cppclass CLargeBinaryArray" arrow::LargeBinaryArray"(CArray):
         const uint8_t* GetValue(int i, int64_t* length)
         shared_ptr[CBuffer] value_data()
         int64_t value_offset(int64_t i)
         int64_t value_length(int64_t i)
+        int64_t total_values_length()
 
     cdef cppclass CStringArray" arrow::StringArray"(CBinaryArray):
         CStringArray(int64_t length, shared_ptr[CBuffer] value_offsets,

python/pyarrow/tests/test_array.py

@@ -110,6 +110,18 @@ def test_binary_format():
     assert result == expected
 
 
+def test_binary_total_values_length():
+    arr = pa.array([b'0000', None, b'11111', b'222222', b'3333333'],
+                   type='binary')
+    large_arr = pa.array([b'0000', None, b'11111', b'222222', b'3333333'],
+                         type='large_binary')
+
+    assert arr.total_values_length == 22
+    assert arr.slice(1, 3).total_values_length == 11
+    assert large_arr.total_values_length == 22
+    assert large_arr.slice(1, 3).total_values_length == 11
+
+
 def test_to_numpy_zero_copy():
     arr = pa.array(range(10))