Re-use decimal formatting

apache · Jun 12, 2021 · c858052 · c858052
1 parent be1a8fd
commit c858052
Show file tree

Hide file tree

Showing 3 changed files with 28 additions and 32 deletions.
diff --git a/arrow/src/array/array_binary.rs b/arrow/src/array/array_binary.rs
@@ -20,8 +20,6 @@ use std::fmt;
 use std::mem;
 use std::{any::Any, iter::FromIterator};
 
-use num::integer::div_rem;
-
 use super::{
     array::print_long_array, raw_pointer::RawPtrBox, Array, ArrayData,
     FixedSizeListArray, GenericBinaryIter, GenericListArray, OffsetSizeTrait,
@@ -668,6 +666,17 @@ impl DecimalArray {
         self.length * i as i32
     }
 
+    #[inline(always)]
+    pub fn value_as_string(&self, row: usize) -> String {
+        let decimal_string = self.value(row).to_string();
+        if self.scale == 0 {
+            decimal_string
+        } else {
+            let splits = decimal_string.split_at(decimal_string.len() - self.scale);
+            format!("{}.{}", splits.0, splits.1)
+        }
+    }
+
     pub fn from_fixed_size_list_array(
         v: FixedSizeListArray,
         precision: usize,
@@ -730,11 +739,10 @@ impl From<ArrayData> for DecimalArray {
 impl fmt::Debug for DecimalArray {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "DecimalArray<{}, {}>\n[\n", self.precision, self.scale)?;
-        let point_index = 10_i128.pow(self.scale as u32);
         print_long_array(self, f, |array, index, f| {
-            let (prefix, suffix) = &div_rem(array.value(index), point_index);
+            let formatted_decimal = array.value_as_string(index);
 
-            write!(f, "{}.{}", prefix, suffix.abs())
+            write!(f, "{}", formatted_decimal)
         })?;
         write!(f, "]")
     }
@@ -1177,7 +1185,7 @@ mod tests {
         decimal_builder.append_null().unwrap();
         let arr = decimal_builder.finish();
         assert_eq!(
-            "DecimalArray<23, 6>\n[\n  8887.0,\n  -8887.0,\n  null,\n]",
+            "DecimalArray<23, 6>\n[\n  8887.000000,\n  -8887.000000,\n  null,\n]",
             format!("{:?}", arr)
         );
     }

diff --git a/arrow/src/csv/writer.rs b/arrow/src/csv/writer.rs
@@ -65,14 +65,12 @@
 //! }
 //! ```
 
-use std::convert::TryInto;
 use std::io::Write;
 
-use num::integer::div_rem;
-
 use crate::datatypes::*;
 use crate::error::{ArrowError, Result};
 use crate::record_batch::RecordBatch;
+use crate::util::display::make_string_from_decimal;
 use crate::{array::*, util::serialization::lexical_to_string};
 const DEFAULT_DATE_FORMAT: &str = "%F";
 const DEFAULT_TIME_FORMAT: &str = "%T";
@@ -245,14 +243,7 @@ impl<W: Write> Writer<W> {
                     };
                     format!("{}", datetime.format(&self.timestamp_format))
                 }
-                DataType::Decimal(_precision, scale) => {
-                    let c = col.as_any().downcast_ref::<DecimalArray>().unwrap();
-                    let value = c.value(row_index);
-                    let (prefix, suffix) =
-                        div_rem(value, 10_i128.pow((*scale).try_into().unwrap()));
-
-                    format!("{}.{}", prefix, suffix.abs())
-                }
+                DataType::Decimal(..) => make_string_from_decimal(col, row_index)?,
                 t => {
                     // List and Struct arrays not supported by the writer, any
                     // other type needs to be implemented

diff --git a/arrow/src/util/display.rs b/arrow/src/util/display.rs
@@ -19,6 +19,8 @@
 //! purposes. See the `pretty` crate for additional functions for
 //! record batch pretty printing.
 
+use std::sync::Arc;
+
 use crate::array::Array;
 use crate::datatypes::{
     ArrowNativeType, ArrowPrimitiveType, DataType, Int16Type, Int32Type, Int64Type,
@@ -192,18 +194,15 @@ macro_rules! make_string_from_list {
     }};
 }
 
-macro_rules! make_string_from_decimal {
-    ($array_type: ty, $column: ident, $row: ident, $scale: ident) => {{
-        let array = $column.as_any().downcast_ref::<$array_type>().unwrap();
-        let decimal_string = array.value($row).to_string();
-        let formatted_decimal = if *$scale == 0 {
-            decimal_string
-        } else {
-            let splits = decimal_string.split_at(decimal_string.len() - *$scale);
-            format!("{}.{}", splits.0, splits.1)
-        };
-        Ok(formatted_decimal)
-    }};
+#[inline(always)]
+pub fn make_string_from_decimal(column: &Arc<dyn Array>, row: usize) -> Result<String> {
+    let array = column
+        .as_any()
+        .downcast_ref::<array::DecimalArray>()
+        .unwrap();
+
+    let formatted_decimal = array.value_as_string(row);
+    Ok(formatted_decimal)
 }
 
 /// Get the value at the given row in an array as a String.
@@ -231,9 +230,7 @@ pub fn array_value_to_string(column: &array::ArrayRef, row: usize) -> Result<Str
         DataType::Float16 => make_string!(array::Float32Array, column, row),
         DataType::Float32 => make_string!(array::Float32Array, column, row),
         DataType::Float64 => make_string!(array::Float64Array, column, row),
-        DataType::Decimal(_, scale) => {
-            make_string_from_decimal!(array::DecimalArray, column, row, scale)
-        }
+        DataType::Decimal(..) => make_string_from_decimal(column, row),
         DataType::Timestamp(unit, _) if *unit == TimeUnit::Second => {
             make_string_datetime!(array::TimestampSecondArray, column, row)
         }