使用Python ReportLab从DataFrame生成PDF的三个问题求助

针对你提到的三个功能需求，下面是具体的实现方案和修改后的完整代码：

1. 每页显示表头 #

ReportLab默认的Table不支持跨页重复表头，需要自定义Flowable类重写split方法，实现分页时自动插入表头行。

2. 指定列宽 #

创建Table对象时，通过colWidths参数直接设置各列宽度，支持固定数值或按页面比例分配两种方式。

3. 单元格文本自动换行并自适应高度 #

将单元格内容转换为Paragraph对象，配合自定义ParagraphStyle开启自动换行，Table会根据内容自动调整行高。

修改后的完整代码 #

import pandas as pd
from reportlab.lib.pagesizes import letter
from reportlab.platypus import SimpleDocTemplate, Table, TableStyle, Paragraph, Flowable
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import inch

# 自定义带重复表头的表格类
class TableWithHeader(Flowable):
    def __init__(self, table_data, col_widths, table_style):
        self.table_data = table_data
        self.col_widths = col_widths
        self.table_style = table_style
        self.header = table_data[0]
        self.data_rows = table_data[1:]
        self.page_height = letter[1] - 2*inch  # 减去上下边距

    def wrap(self, avail_width, avail_height):
        # 计算单一行的高度
        sample_table = Table([self.header] + [self.data_rows[0]], colWidths=self.col_widths)
        sample_table.setStyle(self.table_style)
        _, row_height = sample_table.wrap(avail_width, avail_height)
        self.row_height = row_height
        return avail_width, len(self.data_rows)*self.row_height

    def split(self, avail_width, avail_height):
        # 计算每页能容纳的数据行数
        max_rows_per_page = int((self.page_height - self.row_height) // self.row_height)
        chunks = []
        for i in range(0, len(self.data_rows), max_rows_per_page):
            chunk_data = [self.header] + self.data_rows[i:i+max_rows_per_page]
            chunk_table = Table(chunk_data, colWidths=self.col_widths)
            chunk_table.setStyle(self.table_style)
            chunks.append(chunk_table)
        return chunks

# Path to the Excel file
file_path = 'file.xlsx'

# Load the second sheet into a data frame, skipping two rows
df = pd.read_excel(file_path, sheet_name='mainsheet', skiprows=2)

# Columns used for grouping
group_columns = ['Country', 'State', 'City']

grouped_df = df.groupby(group_columns)

# Create the PDF document
doc = SimpleDocTemplate("output.pdf", pagesize=letter, leftMargin=0.5*inch, rightMargin=0.5*inch, topMargin=0.5*inch, bottomMargin=0.5*inch)

# Create a list to hold the PDF content
elements = []

# 定义单元格文本样式（支持自动换行）
cell_style = ParagraphStyle(
    name='CellStyle',
    fontName='Helvetica',
    fontSize=10,
    leading=12,  # 行间距
    wordWrap='CJK'  # 自动换行，兼容中英文
)

# Define the table style
table_style = TableStyle([
    ('BACKGROUND', (0, 0), (-1, 0), 'gray'),
    ('TEXTCOLOR', (0, 0), (-1, 0), 'white'),
    ('ALIGN', (0, 0), (-1, 0), 'CENTER'),
    ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
    ('FONTSIZE', (0, 0), (-1, 0), 12),
    ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
    ('BACKGROUND', (0, 1), (-1, -1), 'white'),
    ('GRID', (0, 0), (-1, -1), 1, 'gray'),
    ('VALIGN', (0, 0), (-1, -1), 'TOP'),  # 单元格内容顶部对齐
])

# 指定列宽（示例：按页面宽度比例分配，总宽度减去边距）
total_width = letter[0] - doc.leftMargin - doc.rightMargin
col_widths = [total_width*0.2, total_width*0.2, total_width*0.2, total_width*0.4]  # 四列按2:2:2:4分配

# Iterate over the grouped dataframe
for group_key, group_df in grouped_df:
    # Add the group information as a header
    group_info = "Group: " + " / ".join(str(val) for val in group_key)
    header_paragraph = Paragraph(group_info, getSampleStyleSheet()['Heading2'])
    elements.append(header_paragraph)

    # 将DataFrame数据转换为包含Paragraph的列表（支持自动换行）
    header = [Paragraph(col, getSampleStyleSheet()['Heading4']) for col in group_df.columns.tolist()]
    data_rows = []
    for row in group_df.values.tolist():
        data_row = [Paragraph(str(cell), cell_style) for cell in row]
        data_rows.append(data_row)
    table_data = [header] + data_rows

    # 创建带重复表头的表格
    table = TableWithHeader(table_data, col_widths, table_style)
    elements.append(table)

    # Add a page break after each group
    elements.append(Paragraph("<br/><br/>", getSampleStyleSheet()['Normal']))

# Build the PDF document
doc.build(elements)

关键修改说明 #

• 每页重复表头：通过TableWithHeader类的split方法，在分页时自动截取数据块并添加表头。
• 指定列宽：col_widths参数可设置固定值（如[1*inch, 1*inch]）或比例值，适配不同页面需求。
• 自动换行与自适应高度：所有单元格内容转为Paragraph对象，开启wordWrap属性实现自动换行，Table会根据内容高度自动调整行高。

内容的提问来源于stack exchange，提问作者Prabhat Sharma