IronXLを使用して C# で CSV ファイルを高速に読み取るにはどうすればよいでしょうか?

Install-Package IronXL
dotnet add package IronXL

using IronXL;

// Load CSV file directly into a workbook
WorkBook workbook = WorkBook.LoadCSV("sales_data.csv", fileFormat: ExcelFileFormat.XLSX);

// Access the default worksheet containing CSV data
WorkSheet sheet = workbook.DefaultWorkSheet;

// Read specific cell values using Excel-style addressing
string customerName = sheet["A2"].StringValue;
decimal orderTotal = sheet["D2"].DecimalValue;

// Iterate through all data rows
foreach (var row in sheet.Rows)
{
    Console.WriteLine($"Row {row.RowNumber}: {row.Columns[0].Value}");
}

Imports IronXL

' Load CSV file directly into a workbook
Dim workbook As WorkBook = WorkBook.LoadCSV("sales_data.csv", fileFormat:=ExcelFileFormat.XLSX)

' Access the default worksheet containing CSV data
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Read specific cell values using Excel-style addressing
Dim customerName As String = sheet("A2").StringValue
Dim orderTotal As Decimal = sheet("D2").DecimalValue

' Iterate through all data rows
For Each row In sheet.Rows
    Console.WriteLine($"Row {row.RowNumber}: {row.Columns(0).Value}")
Next

using IronXL;

// Load semicolon-delimited CSV (common in European formats)
WorkBook europeanData = WorkBook.LoadCSV("german_report.csv",
    fileFormat: ExcelFileFormat.XLSX,
    listDelimiter: ";");

// Load tab-separated values file
WorkBook tsvData = WorkBook.LoadCSV("research_data.tsv",
    fileFormat: ExcelFileFormat.XLSX,
    listDelimiter: "\t");

// Load pipe-delimited file (common in legacy systems)
WorkBook pipeData = WorkBook.LoadCSV("legacy_export.csv",
    fileFormat: ExcelFileFormat.XLSX,
    listDelimiter: "|");

// Access data identically regardless of original delimiter
WorkSheet sheet = europeanData.DefaultWorkSheet;
Console.WriteLine($"First value: {sheet["A1"].Value}");

Imports IronXL

' Load semicolon-delimited CSV (common in European formats)
Dim europeanData As WorkBook = WorkBook.LoadCSV("german_report.csv", fileFormat:=ExcelFileFormat.XLSX, listDelimiter:=";")

' Load tab-separated values file
Dim tsvData As WorkBook = WorkBook.LoadCSV("research_data.tsv", fileFormat:=ExcelFileFormat.XLSX, listDelimiter:=vbTab)

' Load pipe-delimited file (common in legacy systems)
Dim pipeData As WorkBook = WorkBook.LoadCSV("legacy_export.csv", fileFormat:=ExcelFileFormat.XLSX, listDelimiter:="|")

' Access data identically regardless of original delimiter
Dim sheet As WorkSheet = europeanData.DefaultWorkSheet
Console.WriteLine($"First value: {sheet("A1").Value}")

using IronXL;
using System.Data;

// Load CSV and convert to DataTable
WorkBook workbook = WorkBook.LoadCSV("customers.csv", ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.DefaultWorkSheet;

// Convert worksheet to DataTable (first row becomes column headers)
DataTable customerTable = sheet.ToDataTable(true);

// Access data using standard DataTable operations
foreach (DataRow row in customerTable.Rows)
{
    Console.WriteLine($"Customer: {row["Name"]}, Email: {row["Email"]}");
}

// Use with LINQ for filtering and transformation
var activeCustomers = customerTable.AsEnumerable()
    .Where(r => r.Field<string>("Status") == "Active")
    .ToList();

int totalCount = customerTable.Rows.Count;
Console.WriteLine($"Processed {totalCount} customer records");

Imports IronXL
Imports System.Data
Imports System.Linq

' Load CSV and convert to DataTable
Dim workbook As WorkBook = WorkBook.LoadCSV("customers.csv", ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Convert worksheet to DataTable (first row becomes column headers)
Dim customerTable As DataTable = sheet.ToDataTable(True)

' Access data using standard DataTable operations
For Each row As DataRow In customerTable.Rows
    Console.WriteLine($"Customer: {row("Name")}, Email: {row("Email")}")
Next

' Use with LINQ for filtering and transformation
Dim activeCustomers = customerTable.AsEnumerable() _
    .Where(Function(r) r.Field(Of String)("Status") = "Active") _
    .ToList()

Dim totalCount As Integer = customerTable.Rows.Count
Console.WriteLine($"Processed {totalCount} customer records")

using IronXL;

// Load CSV data
WorkBook workbook = WorkBook.LoadCSV("quarterly_sales.csv", ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.DefaultWorkSheet;

// Add formatting to make the data presentable
sheet["A1:D1"].Style.Font.Bold = true;
sheet["A1:D1"].Style.SetBackgroundColor("#4472C4");

// Add a formula to calculate totals
sheet["E2"].Formula = "=SUM(B2:D2)";

// Save as Excel format
workbook.SaveAs("quarterly_sales_formatted.xlsx");

// Or save back to CSV when needed
workbook.SaveAsCsv("quarterly_sales_processed.csv");

Imports IronXL

' Load CSV data
Dim workbook As WorkBook = WorkBook.LoadCSV("quarterly_sales.csv", ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Add formatting to make the data presentable
sheet("A1:D1").Style.Font.Bold = True
sheet("A1:D1").Style.SetBackgroundColor("#4472C4")

' Add a formula to calculate totals
sheet("E2").Formula = "=SUM(B2:D2)"

' Save as Excel format
workbook.SaveAs("quarterly_sales_formatted.xlsx")

' Or save back to CSV when needed
workbook.SaveAsCsv("quarterly_sales_processed.csv")

using IronXL;

// Load large CSV file
WorkBook workbook = WorkBook.LoadCSV("large_dataset.csv", ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.DefaultWorkSheet;

// Process data in manageable chunks using range selection
int batchSize = 10000;
int totalRows = sheet.RowCount;

for (int i = 1; i <= totalRows; i += batchSize)
{
    int endRow = Math.Min(i + batchSize - 1, totalRows);

    // Select a range of rows for processing
    var batch = sheet[$"A{i}:Z{endRow}"];
    foreach (var cell in batch)
    {
        ProcessRecord(cell.Value);
    }

    // Release memory between batches for very large files
    GC.Collect();
}

// Alternative: Process row by row for maximum control
for (int i = 0; i < sheet.RowCount; i++)
{
    var row = sheet.Rows[i];
    // Process individual row data
}

Imports IronXL

' Load large CSV file
Dim workbook As WorkBook = WorkBook.LoadCSV("large_dataset.csv", ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Process data in manageable chunks using range selection
Dim batchSize As Integer = 10000
Dim totalRows As Integer = sheet.RowCount

For i As Integer = 1 To totalRows Step batchSize
    Dim endRow As Integer = Math.Min(i + batchSize - 1, totalRows)

    ' Select a range of rows for processing
    Dim batch = sheet($"A{i}:Z{endRow}")
    For Each cell In batch
        ProcessRecord(cell.Value)
    Next

    ' Release memory between batches for very large files
    GC.Collect()
Next

' Alternative: Process row by row for maximum control
For i As Integer = 0 To sheet.RowCount - 1
    Dim row = sheet.Rows(i)
    ' Process individual row data
Next

using IronXL;

// This code runs identically on Windows, Linux, macOS, Docker, Azure, and AWS
WorkBook workbook = WorkBook.LoadCSV("data.csv", ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.DefaultWorkSheet;

// Platform-agnostic file operations
string outputPath = Path.Combine(Environment.CurrentDirectory, "output.xlsx");
workbook.SaveAs(outputPath);

Console.WriteLine($"Processed on: {Environment.OSVersion.Platform}");
Console.WriteLine($"Output saved to: {outputPath}");

bool success = File.Exists(outputPath);

Imports IronXL
Imports System.IO

' This code runs identically on Windows, Linux, macOS, Docker, Azure, and AWS
Dim workbook As WorkBook = WorkBook.LoadCSV("data.csv", ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' Platform-agnostic file operations
Dim outputPath As String = Path.Combine(Environment.CurrentDirectory, "output.xlsx")
workbook.SaveAs(outputPath)

Console.WriteLine($"Processed on: {Environment.OSVersion.Platform}")
Console.WriteLine($"Output saved to: {outputPath}")

Dim success As Boolean = File.Exists(outputPath)