calamine

An Excel/OpenDocument Spreadsheets file reader/deserializer, in pure Rust.

Documentation

Description

calamine is a pure Rust library to read and deserialize any spreadsheet file:

• excel like (xls, xlsx, xlsm, xlsb, xla, xlam)
• opendocument spreadsheets (ods)

As long as your files are simple enough, this library should just work. For anything else, please file an issue with a failing test or send a pull request!

Examples

Serde deserialization

It is as simple as:

use calamine::{open_workbook, Error, Xlsx, Reader, RangeDeserializerBuilder};

fn example() -> Result<(), Error> {
    let path = format!("{}/tests/temperature.xlsx", env!("CARGO_MANIFEST_DIR"));
    let mut workbook: Xlsx<_> = open_workbook(path)?;
    let range = workbook.worksheet_range("Sheet1")?;


    let mut iter = RangeDeserializerBuilder::new().from_range(&range)?;

    if let Some(result) = iter.next() {
        let (label, value): (String, f64) = result?;
        assert_eq!(label, "celsius");
        assert_eq!(value, 22.2222);
        Ok(())
    } else {
        Err(From::from("expected at least one record but got none"))
    }
}

Calamine provides helper functions to deal with invalid type values. For instance, to deserialize a column which should contain floats but may also contain invalid values (i.e. strings), you can use the deserialize_as_f64_or_none helper function with Serde's deserialize_with field attribute:

use calamine::{deserialize_as_f64_or_none, open_workbook, RangeDeserializerBuilder, Reader, Xlsx};
use serde::Deserialize;

#[derive(Deserialize)]
struct Record {
    metric: String,
    #[serde(deserialize_with = "deserialize_as_f64_or_none")]
    value: Option<f64>,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let path = format!("{}/tests/excel.xlsx", env!("CARGO_MANIFEST_DIR"));
    let mut excel: Xlsx<_> = open_workbook(path)?;

    let range = excel
        .worksheet_range("Sheet1")
        .map_err(|_| calamine::Error::Msg("Cannot find Sheet1"))?;

    let iter_records =
        RangeDeserializerBuilder::with_headers(&["metric", "value"]).from_range(&range)?;

    for result in iter_records {
        let record: Record = result?;
        println!("metric={:?}, value={:?}", record.metric, record.value);
    }

    Ok(())
}

The deserialize_as_f64_or_none function discards all invalid values. If instead you would like to return them as Strings, you can use the similar deserialize_as_f64_or_string function.

Reader: Simple

use calamine::{Reader, Xlsx, open_workbook};

let mut excel: Xlsx<_> = open_workbook("file.xlsx").unwrap();
if let Some(Ok(r)) = excel.worksheet_range("Sheet1") {
    for row in r.rows() {
        println!("row={:?}, row[0]={:?}", row, row[0]);
    }
}

Reader: With header row

use calamine::{Reader, Xlsx, open_workbook};

let mut excel: Xlsx<_> = open_workbook("file.xlsx").unwrap();

let sheet1 = excel
    .with_header_row(Some(3))
    .worksheet_range("Sheet1")
    .unwrap();

Note that xlsx and xlsb files support lazy loading, so specifying a header row takes effect immediately when reading a sheet range. In contrast, for xls and ods files, all sheets are loaded at once when opening the workbook with default settings. As a result, setting the header row only applies afterward and does not provide any performance benefits.

Reader: More complex

Let's assume

• the file type (xls, xlsx ...) cannot be known at static time
• we need to get all data from the workbook
• we need to parse the vba
• we need to see the defined names
• and the formula!

use calamine::{Reader, open_workbook_auto, Xlsx, DataType};

// opens a new workbook
let path = ...; // we do not know the file type
let mut workbook = open_workbook_auto(path).expect("Cannot open file");

// Read whole worksheet data and provide some statistics
if let Some(Ok(range)) = workbook.worksheet_range("Sheet1") {
    let total_cells = range.get_size().0 * range.get_size().1;
    let non_empty_cells: usize = range.used_cells().count();
    println!("Found {} cells in 'Sheet1', including {} non empty cells",
             total_cells, non_empty_cells);
    // alternatively, we can manually filter rows
    assert_eq!(non_empty_cells, range.rows()
        .flat_map(|r| r.iter().filter(|&c| c != &DataType::Empty)).count());
}

// Check if the workbook has a vba project
if let Some(Ok(mut vba)) = workbook.vba_project() {
    let vba = vba.to_mut();
    let module1 = vba.get_module("Module 1").unwrap();
    println!("Module 1 code:");
    println!("{}", module1);
    for r in vba.get_references() {
        if r.is_missing() {
            println!("Reference {} is broken or not accessible", r.name);
        }
    }
}

// You can also get defined names definition (string representation only)
for name in workbook.defined_names() {
    println!("name: {}, formula: {}", name.0, name.1);
}

// Now get all formula!
let sheets = workbook.sheet_names().to_owned();
for s in sheets {
    println!("found {} formula in '{}'",
             workbook
                .worksheet_formula(&s)
                .expect("sheet not found")
                .expect("error while getting formula")
                .rows().flat_map(|r| r.iter().filter(|f| !f.is_empty()))
                .count(),
             s);
}

Features

• dates: Add date related fn to DataType.
• picture: Extract picture data.

Others

Browse the examples directory.

Performance

As calamine is readonly, the comparisons will only involve reading an excel xlsx file and then iterating over the rows. Along with calamine, three other libraries were chosen, from three different languages:

• excelize written in go
• ClosedXML written in C#
• openpyxl written in python

The benchmarks were done using this dataset, a 186MB xlsx file when the csv is converted. The plotting data was gotten from the sysinfo crate, at a sample interval of 200ms. The program samples the reported values for the running process and records it.

The programs are all structured to follow the same constructs:

calamine:

use calamine::{open_workbook, Reader, Xlsx};

fn main() {
    // Open workbook
    let mut excel: Xlsx<_> =
        open_workbook("NYC_311_SR_2010-2020-sample-1M.xlsx").expect("failed to find file");

    // Get worksheet
    let sheet = excel
        .worksheet_range("NYC_311_SR_2010-2020-sample-1M")
        .unwrap()
        .unwrap();

    // iterate over rows
    for _row in sheet.rows() {}
}

excelize:

package main

import (
        "fmt"
        "github.com/xuri/excelize/v2"
)

func main() {
        // Open workbook
        file, err := excelize.OpenFile(`NYC_311_SR_2010-2020-sample-1M.xlsx`)

        if err != nil {
                fmt.Println(err)
                return
        }

        defer func() {
                // Close the spreadsheet.
                if err := file.Close(); err != nil {
                        fmt.Println(err)
                }
        }()

        // Select worksheet
        rows, err := file.Rows("NYC_311_SR_2010-2020-sample-1M")
        if err != nil {
                fmt.Println(err)
                return
        }

        // Iterate over rows
        for rows.Next() {
        }
}

ClosedXML:

using ClosedXML.Excel;

internal class Program
{
        private static void Main(string[] args)
        {
                // Open workbook
                using var workbook = new XLWorkbook("NYC_311_SR_2010-2020-sample-1M.xlsx");

                // Get Worksheet
                // "NYC_311_SR_2010-2020-sample-1M"
                var worksheet = workbook.Worksheet(1);

                // Iterate over rows
                foreach (var row in worksheet.Rows())
                {

                }
        }
}

openpyxl:

from openpyxl import load_workbook

# Open workbook
wb = load_workbook(
    filename=r'NYC_311_SR_2010-2020-sample-1M.xlsx', read_only=True)

# Get worksheet
ws = wb['NYC_311_SR_2010-2020-sample-1M']

# Iterate over rows
for row in ws.rows:
    _ = row

# Close the workbook after reading
wb.close()

Benchmarks

The benchmarking was done using hyperfine with --warmup 3 on an AMD RYZEN 9 5900X @ 4.0GHz running Windows 11. Both calamine and ClosedXML were built in release mode.

0.22.1 calamine.exe
  Time (mean ± σ):     25.278 s ±  0.424 s    [User: 24.852 s, System: 0.470 s]
  Range (min … max):   24.980 s … 26.369 s    10 runs

v2.8.0 excelize.exe
  Time (mean ± σ):     44.254 s ±  0.574 s    [User: 46.071 s, System: 7.754 s]
  Range (min … max):   42.947 s … 44.911 s    10 runs

0.102.1 closedxml.exe
  Time (mean ± σ):     178.343 s ±  3.673 s    [User: 177.442 s, System: 2.612 s]
  Range (min … max):   173.232 s … 185.086 s    10 runs

3.0.10 openpyxl.py
  Time (mean ± σ):     238.554 s ±  1.062 s    [User: 238.016 s, System: 0.661 s]
  Range (min … max):   236.798 s … 240.167 s    10 runs

calamine is 1.75x faster than excelize, 7.05x faster than ClosedXML, and 9.43x faster than openpyxl.

The spreadsheet has a range of 1,000,001 rows and 41 columns, for a total of 41,000,041 cells in the range. Of those, 28,056,975 cells had values.

Going off of that number:

• calamine => 1,122,279 cells per second
• excelize => 633,998 cells per second
• ClosedXML => 157,320 cells per second
• openpyxl => 117,612 cells per second

Plots

Disk Read

As stated, the filesize on disk is 186MB:

• calamine => 186MB
• ClosedXML => 208MB.
• openpyxl => 192MB.
• excelize => 1.5GB.

When asking one of the maintainers of excelize, I got this response:

To avoid high memory usage for reading large files, this library allows user-specific UnzipXMLSizeLimit options when opening the workbook, to set the memory limit on the unzipping worksheet and shared string table in bytes, worksheet XML will be extracted to the system temporary directory when the file size is over this value, so you can see that data written in reading mode, and you can change the default for that to avoid this behavior.

- xuri

Disk Write

As seen in the previous section, excelize is writting to disk to save memory. The others don't employ that kind of mechanism.

Memory

[!NOTE] ClosedXML was reporting a constant 2.5TB of virtual memory usage, so it was excluded from the chart.

The stepping and falling for calamine is from the grows of Vecs and the freeing of memory right after, with the memory usage dropping down again. The sudden jump at the end is when the sheet is being read into memory. The others, being garbage collected, have a more linear climb all the way through.

CPU

Very noisy chart, but excelize's spikes must be from the GC?

Unsupported

Many (most) part of the specifications are not implemented, the focus has been put on reading cell values and vba code.

The main unsupported items are:

• no support for writing excel files, this is a read-only library
• no support for reading extra contents, such as formatting, excel parameter, encrypted components etc ...
• no support for reading VB for opendocuments

Credits

Thanks to xlsx-js developers! This library is by far the simplest open source implementation I could find and helps making sense out of official documentation.

Thanks also to all the contributors!

License

MIT