arrow 3.0.0

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Utilities for printing record batches. Note this module is not
//! available unless `feature = "prettyprint"` is enabled.

use crate::record_batch::RecordBatch;

use prettytable::format;
use prettytable::{Cell, Row, Table};

use crate::error::Result;

use super::display::array_value_to_string;

///! Create a visual representation of record batches
pub fn pretty_format_batches(results: &[RecordBatch]) -> Result<String> {
    Ok(create_table(results)?.to_string())
}

///! Prints a visual representation of record batches to stdout
pub fn print_batches(results: &[RecordBatch]) -> Result<()> {
    create_table(results)?.printstd();
    Ok(())
}

///! Convert a series of record batches into a table
fn create_table(results: &[RecordBatch]) -> Result<Table> {
    let mut table = Table::new();
    table.set_format(*format::consts::FORMAT_NO_LINESEP_WITH_TITLE);

    if results.is_empty() {
        return Ok(table);
    }

    let schema = results[0].schema();

    let mut header = Vec::new();
    for field in schema.fields() {
        header.push(Cell::new(&field.name()));
    }
    table.set_titles(Row::new(header));

    for batch in results {
        for row in 0..batch.num_rows() {
            let mut cells = Vec::new();
            for col in 0..batch.num_columns() {
                let column = batch.column(col);
                cells.push(Cell::new(&array_value_to_string(&column, row)?));
            }
            table.add_row(Row::new(cells));
        }
    }

    Ok(table)
}

#[cfg(test)]
mod tests {
    use crate::array::{self, PrimitiveBuilder, StringBuilder, StringDictionaryBuilder};

    use super::*;
    use crate::datatypes::{DataType, Field, Int32Type, Schema};
    use std::sync::Arc;

    #[test]
    fn test_pretty_format_batches() -> Result<()> {
        // define a schema.
        let schema = Arc::new(Schema::new(vec![
            Field::new("a", DataType::Utf8, true),
            Field::new("b", DataType::Int32, true),
        ]));

        // define data.
        let batch = RecordBatch::try_new(
            schema,
            vec![
                Arc::new(array::StringArray::from(vec![
                    Some("a"),
                    Some("b"),
                    None,
                    Some("d"),
                ])),
                Arc::new(array::Int32Array::from(vec![
                    Some(1),
                    None,
                    Some(10),
                    Some(100),
                ])),
            ],
        )?;

        let table = pretty_format_batches(&[batch])?;

        let expected = vec![
            "+---+-----+",
            "| a | b   |",
            "+---+-----+",
            "| a | 1   |",
            "| b |     |",
            "|   | 10  |",
            "| d | 100 |",
            "+---+-----+",
        ];

        let actual: Vec<&str> = table.lines().collect();

        assert_eq!(expected, actual, "Actual result:\n{}", table);

        Ok(())
    }

    #[test]
    fn test_pretty_format_dictionary() -> Result<()> {
        // define a schema.
        let field_type =
            DataType::Dictionary(Box::new(DataType::Int32), Box::new(DataType::Utf8));
        let schema = Arc::new(Schema::new(vec![Field::new("d1", field_type, true)]));

        let keys_builder = PrimitiveBuilder::<Int32Type>::new(10);
        let values_builder = StringBuilder::new(10);
        let mut builder = StringDictionaryBuilder::new(keys_builder, values_builder);

        builder.append("one")?;
        builder.append_null()?;
        builder.append("three")?;
        let array = Arc::new(builder.finish());

        let batch = RecordBatch::try_new(schema, vec![array])?;

        let table = pretty_format_batches(&[batch])?;

        let expected = vec![
            "+-------+",
            "| d1    |",
            "+-------+",
            "| one   |",
            "|       |",
            "| three |",
            "+-------+",
        ];

        let actual: Vec<&str> = table.lines().collect();

        assert_eq!(expected, actual, "Actual result:\n{}", table);

        Ok(())
    }
}