Wie man Tabellendaten aus einer PDF-Datei in C# extrahiert

When Would You Need to Extract Tables from PDF Documents?

Tables are a handy way of structuring and displaying your data, whether carrying out inventory management, data entry, recording data such as rainfall, etc. Thus, there may also be many reasons for needing to extract tables and table data from PDF documents. Some of the most common use cases include:

• Automating data entry: Extracting data from tables in PDF reports or invoices can automate processes like populating databases or spreadsheets.
• Data analysis: Businesses often receive structured reports in PDF format. Extracting tables allows you to analyze this data programmatically.
• Document conversion: Extracting tabular data into more accessible formats like Excel or CSV enables easier manipulation, storage, and sharing.
• Auditing and compliance: For legal or financial records, extracting tabular data from PDF documents programmatically can help automate audits and ensure compliance.

How Do PDF Tables Work?

The PDF file format does not offer any native ability to store data in structured formats like tables. The table we use in today's example was created in HTML, before being converted to PDF format. Tables are rendered as text and lines, so extracting table data often requires some parsing and interpreting of content unless you are using OCR software, such as IronOCR.

How to Extract Table Data from a PDF File in C#

Before we explore how IronPDF can tackle this task, let's first explore an online tool capable of handling PDF extraction. To extract a table from a PDF document using an online PDF tool, follow the steps outlined below:

1. Navigate to the free online PDF extraction tool
2. Upload the PDF containing the table
3. View and download the results

Extract Table Data Using IronPDF

IronPDF allows you to extract data, text, and graphics from PDFs, which can then be used to reconstruct tables programmatically. To do this, you will first need to extract the textual content from the table in the PDF and then use that text to parse the table into rows and columns. Before we start extracting tables, let's take a look at how IronPDF's ExtractAllText() method works by extracting the data within a table:

using IronPDF;

class Program
{
    static void Main(string[] args)
    {
        // Load the PDF document
        PdfDocument pdf = PdfDocument.FromFile("example.pdf");

        // Extract all text from the PDF
        string text = pdf.ExtractAllText();

        // Output the extracted text to the console
        Console.WriteLine(text);
    }
}

using IronPDF;

class Program
{
    static void Main(string[] args)
    {
        // Load the PDF document
        PdfDocument pdf = PdfDocument.FromFile("example.pdf");

        // Extract all text from the PDF
        string text = pdf.ExtractAllText();

        // Output the extracted text to the console
        Console.WriteLine(text);
    }
}

Imports IronPDF

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		' Load the PDF document
		Dim pdf As PdfDocument = PdfDocument.FromFile("example.pdf")

		' Extract all text from the PDF
		Dim text As String = pdf.ExtractAllText()

		' Output the extracted text to the console
		Console.WriteLine(text)
	End Sub
End Class

In this example, we have loaded the PDF document using the PdfDocument class, and then used the ExtractAllText() method to extract all the text within the document, before finally displaying the text on the console.

Extracting Table Data from Text Using IronPDF

After extracting text from the PDF, the table will appear as a series of rows and columns in plain text. You can split this text based on line breaks (\n) and then further split rows into columns based on consistent spacing or delimiters such as commas or tabs. Here is a basic example of how to parse the table from the text:

using IronPDF;
using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        // Load the PDF document
        PdfDocument pdf = PdfDocument.FromFile("table.pdf");

        // Extract all text from the PDF
        string text = pdf.ExtractAllText();

        // Split the text into lines (rows)
        string[] lines = text.Split('\n');

        foreach (string line in lines)
        {
            // Split the line into columns using the tab character
            string[] columns = line.Split('\t').Where(col => !string.IsNullOrWhiteSpace(col)).ToArray();
            Console.WriteLine("Row:");

            foreach (string column in columns)
            {
                Console.WriteLine("  " + column); // Output each column in the row
            }
        }
    }
}

using IronPDF;
using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        // Load the PDF document
        PdfDocument pdf = PdfDocument.FromFile("table.pdf");

        // Extract all text from the PDF
        string text = pdf.ExtractAllText();

        // Split the text into lines (rows)
        string[] lines = text.Split('\n');

        foreach (string line in lines)
        {
            // Split the line into columns using the tab character
            string[] columns = line.Split('\t').Where(col => !string.IsNullOrWhiteSpace(col)).ToArray();
            Console.WriteLine("Row:");

            foreach (string column in columns)
            {
                Console.WriteLine("  " + column); // Output each column in the row
            }
        }
    }
}

Imports Microsoft.VisualBasic
Imports IronPDF
Imports System
Imports System.Linq

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		' Load the PDF document
		Dim pdf As PdfDocument = PdfDocument.FromFile("table.pdf")

		' Extract all text from the PDF
		Dim text As String = pdf.ExtractAllText()

		' Split the text into lines (rows)
		Dim lines() As String = text.Split(ControlChars.Lf)

		For Each line As String In lines
			' Split the line into columns using the tab character
			Dim columns() As String = line.Split(ControlChars.Tab).Where(Function(col) Not String.IsNullOrWhiteSpace(col)).ToArray()
			Console.WriteLine("Row:")

			For Each column As String In columns
				Console.WriteLine("  " & column) ' Output each column in the row
			Next column
		Next line
	End Sub
End Class

In this example, we followed the same steps as before for loading our PDF document and extracting the text. Then, using text.Split('\n') we split the extracted text into rows based on line breaks and store the results in the lines array. A foreach loop is then used to loop through the rows in the array, where line.Split('\t') is used to further split the rows into columns using the tab character '\t' as the delimiter. The next part of the columns array, Where(col => !string.IsNullOrWhiteSpace(col)).ToArray() filters out empty columns that may arise due to extra spaces, and then adds the columns to the column array.

Finally, we write text to the console output window with basic row and column structuring.

Exporting Extracted Table Data to CSV

Now that we've covered how to extract tables from PDF files, let's take a look at what we can do with that extracted data. Exporting the exported table as a CSV file is one useful way of handling table data and automating tasks such as data entry. For this example, we have filled a table with simulated data, in this case, the daily rainfall amount in a week, extracted the table from the PDF, and then exported it to a CSV file.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using IronPDF;

class Program
{
    static void Main(string[] args)
    {
        string pdfPath = "table.pdf";
        string csvPath = "output.csv";

        // Extract and parse table data
        var tableData = ExtractTableDataFromPdf(pdfPath);

        // Write the extracted data to a CSV file
        WriteDataToCsv(tableData, csvPath);
        Console.WriteLine($"Data extracted and saved to {csvPath}");
    }

    static List<string[]> ExtractTableDataFromPdf(string pdfPath)
    {
        var pdf = PdfDocument.FromFile(pdfPath);

        // Extract text from the first page
        var text = pdf.ExtractTextFromPage(0); 
        var rows = new List<string[]>();

        // Split text into lines (rows)
        var lines = text.Split('\n');

        // Variable to hold column values temporarily
        var tempColumns = new List<string>();

        foreach (var line in lines)
        {
            var trimmedLine = line.Trim();

            // Check for empty lines or lines that don't contain table data
            if (string.IsNullOrEmpty(trimmedLine) || trimmedLine.Contains("Header"))
            {
                continue;
            }

            // Split line into columns. Adjust this based on how columns are separated.
            var columns = trimmedLine.Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);

            if (columns.Length > 0)
            {
                // Add columns to temporary list
                tempColumns.AddRange(columns);
                rows.Add(tempColumns.ToArray());
                tempColumns.Clear(); // Clear temporary list after adding to rows
            }
        }

        return rows;
    }

    static void WriteDataToCsv(List<string[]> data, string csvPath)
    {
        using (var writer = new StreamWriter(csvPath))
        {
            foreach (var row in data)
            {
                // Join columns with commas and quote each field to handle commas within data
                var csvRow = string.Join(",", row.Select(field => $"\"{field.Replace("\"", "\"\"")}\""));
                writer.WriteLine(csvRow);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using IronPDF;

class Program
{
    static void Main(string[] args)
    {
        string pdfPath = "table.pdf";
        string csvPath = "output.csv";

        // Extract and parse table data
        var tableData = ExtractTableDataFromPdf(pdfPath);

        // Write the extracted data to a CSV file
        WriteDataToCsv(tableData, csvPath);
        Console.WriteLine($"Data extracted and saved to {csvPath}");
    }

    static List<string[]> ExtractTableDataFromPdf(string pdfPath)
    {
        var pdf = PdfDocument.FromFile(pdfPath);

        // Extract text from the first page
        var text = pdf.ExtractTextFromPage(0); 
        var rows = new List<string[]>();

        // Split text into lines (rows)
        var lines = text.Split('\n');

        // Variable to hold column values temporarily
        var tempColumns = new List<string>();

        foreach (var line in lines)
        {
            var trimmedLine = line.Trim();

            // Check for empty lines or lines that don't contain table data
            if (string.IsNullOrEmpty(trimmedLine) || trimmedLine.Contains("Header"))
            {
                continue;
            }

            // Split line into columns. Adjust this based on how columns are separated.
            var columns = trimmedLine.Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);

            if (columns.Length > 0)
            {
                // Add columns to temporary list
                tempColumns.AddRange(columns);
                rows.Add(tempColumns.ToArray());
                tempColumns.Clear(); // Clear temporary list after adding to rows
            }
        }

        return rows;
    }

    static void WriteDataToCsv(List<string[]> data, string csvPath)
    {
        using (var writer = new StreamWriter(csvPath))
        {
            foreach (var row in data)
            {
                // Join columns with commas and quote each field to handle commas within data
                var csvRow = string.Join(",", row.Select(field => $"\"{field.Replace("\"", "\"\"")}\""));
                writer.WriteLine(csvRow);
            }
        }
    }
}

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.IO
Imports System.Linq
Imports IronPDF

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		Dim pdfPath As String = "table.pdf"
		Dim csvPath As String = "output.csv"

		' Extract and parse table data
		Dim tableData = ExtractTableDataFromPdf(pdfPath)

		' Write the extracted data to a CSV file
		WriteDataToCsv(tableData, csvPath)
		Console.WriteLine($"Data extracted and saved to {csvPath}")
	End Sub

	Private Shared Function ExtractTableDataFromPdf(ByVal pdfPath As String) As List(Of String())
		Dim pdf = PdfDocument.FromFile(pdfPath)

		' Extract text from the first page
		Dim text = pdf.ExtractTextFromPage(0)
		Dim rows = New List(Of String())()

		' Split text into lines (rows)
		Dim lines = text.Split(ControlChars.Lf)

		' Variable to hold column values temporarily
		Dim tempColumns = New List(Of String)()

		For Each line In lines
			Dim trimmedLine = line.Trim()

			' Check for empty lines or lines that don't contain table data
			If String.IsNullOrEmpty(trimmedLine) OrElse trimmedLine.Contains("Header") Then
				Continue For
			End If

			' Split line into columns. Adjust this based on how columns are separated.
			Dim columns = trimmedLine.Split( { " "c, ControlChars.Tab }, StringSplitOptions.RemoveEmptyEntries)

			If columns.Length > 0 Then
				' Add columns to temporary list
				tempColumns.AddRange(columns)
				rows.Add(tempColumns.ToArray())
				tempColumns.Clear() ' Clear temporary list after adding to rows
			End If
		Next line

		Return rows
	End Function

	Private Shared Sub WriteDataToCsv(ByVal data As List(Of String()), ByVal csvPath As String)
		Using writer = New StreamWriter(csvPath)
			For Each row In data
				' Join columns with commas and quote each field to handle commas within data
				Dim csvRow = String.Join(",", row.Select(Function(field) $"""{field.Replace("""", """""")}"""))
				writer.WriteLine(csvRow)
			Next row
		End Using
	End Sub
End Class

Tips and Best Practices

When working with PDF tables, following some basic best practices can help to ensure you minimize the chance of running into any errors or issues.

• Pre-process PDFs: If possible, pre-process your PDFs to ensure consistent formatting, which simplifies the extraction process.
• Validate data: Always validate the extracted data to ensure accuracy and completeness.
• Handle errors: Implement error handling to manage cases where text extraction or parsing fails, such as wrapping your code within a try-catch block.
• Optimize performance: For large PDFs, consider optimizing text extraction and parsing to handle performance issues.

IronPDF Licensing

IronPDF offers different licensing options, allowing you to try out all the powerful features IronPDF has to offer for yourself before committing to a license.

Conclusion

Extracting tables from PDFs using IronPDF is a powerful way to automate data extraction, facilitate analysis, and convert documents into more accessible formats. Whether dealing with simple tables or complex, irregular formats, IronPDF provides the tools needed to extract and process table data efficiently.

With IronPDF, you can streamline workflows such as automated data entry, document conversion, and data analysis. The flexibility and advanced features offered by IronPDF make it a valuable tool for handling various PDF-based tasks.