使用pandas将数据框附加到excel

Question

我希望将数据框附加到excel

这段代码几乎可以满足需求。虽然每次都不附加。我运行它，它将数据框放在excel中。但每次我运行它都不会附加。我也听说openpyxl是cpu密集型但没有听到很多workarounds。

import pandas
from openpyxl import load_workbook

book = load_workbook('C:\\OCC.xlsx')
writer = pandas.ExcelWriter('C:\\OCC.xlsx', engine='openpyxl')
writer.book = book
writer.sheets = dict((ws.title, ws) for ws in book.worksheets)

df1.to_excel(writer, index = False)

writer.save()

我希望每次运行时都追加数据，这种情况不会发生。

数据输出看起来像原始数据：

A   B   C
H   H   H

我希望在第二次跑完之后

A   B    C
H   H    H
H   H    H

抱歉，如果这很明显我是python的新手，我练习的例子并没有按照需要工作。

问题是 - 我每次运行时如何附加数据。我尝试更改为xlsxwriter但获取AttributeError: 'Workbook' object has no attribute 'add_format'

Answer 1

首先，这篇文章是解决方案的第一部分，你应该指定startrow=：Append existing excel sheet with new dataframe using python pandas

你也可以考虑header=False。所以看起来应该是这样的：

df1.to_excel(writer, startrow = 2,index = False, Header = False)

如果你想让它自动到达工作表的末尾并附加你的df，那么使用：

startrow = writer.sheets['Sheet1'].max_row

如果您希望它遍历工作簿中的所有工作表：

for sheetname in writer.sheets:
    df1.to_excel(writer,sheet_name=sheetname, startrow=writer.sheets[sheetname].max_row, index = False,header= False)

顺便说一句：对于writer.sheets你可以使用字典理解（我认为它更干净，但这取决于你，它会产生相同的输出）：

writer.sheets = {ws.title: ws for ws in book.worksheets}

所以完整的代码将是：

import pandas
from openpyxl import load_workbook

book = load_workbook('test.xlsx')
writer = pandas.ExcelWriter('test.xlsx', engine='openpyxl')
writer.book = book
writer.sheets = {ws.title: ws for ws in book.worksheets}

for sheetname in writer.sheets:
    df1.to_excel(writer,sheet_name=sheetname, startrow=writer.sheets[sheetname].max_row, index = False,header= False)

writer.save()

Answer 2

这是一个辅助函数：

def append_df_to_excel(filename, df, sheet_name='Sheet1', startrow=None,
                       truncate_sheet=False, 
                       **to_excel_kwargs):
    """
    Append a DataFrame [df] to existing Excel file [filename]
    into [sheet_name] Sheet.
    If [filename] doesn't exist, then this function will create it.

    Parameters:
      filename : File path or existing ExcelWriter
                 (Example: '/path/to/file.xlsx')
      df : dataframe to save to workbook
      sheet_name : Name of sheet which will contain DataFrame.
                   (default: 'Sheet1')
      startrow : upper left cell row to dump data frame.
                 Per default (startrow=None) calculate the last row
                 in the existing DF and write to the next row...
      truncate_sheet : truncate (remove and recreate) [sheet_name]
                       before writing DataFrame to Excel file
      to_excel_kwargs : arguments which will be passed to `DataFrame.to_excel()`
                        [can be dictionary]

    Returns: None
    """
    from openpyxl import load_workbook

    # ignore [engine] parameter if it was passed
    if 'engine' in to_excel_kwargs:
        to_excel_kwargs.pop('engine')

    writer = pd.ExcelWriter(filename, engine='openpyxl')

    try:
        # try to open an existing workbook
        writer.book = load_workbook(filename)

        # get the last row in the existing Excel sheet
        # if it was not specified explicitly
        if startrow is None and sheet_name in writer.book.sheetnames:
            startrow = writer.book[sheet_name].max_row

        # truncate sheet
        if truncate_sheet and sheet_name in writer.book.sheetnames:
            # index of [sheet_name] sheet
            idx = writer.book.sheetnames.index(sheet_name)
            # remove [sheet_name]
            writer.book.remove(writer.book.worksheets[idx])
            # create an empty sheet [sheet_name] using old index
            writer.book.create_sheet(sheet_name, idx)

        # copy existing sheets
        writer.sheets = {ws.title:ws for ws in writer.book.worksheets}
    except FileNotFoundError:
        # file does not exist yet, we will create it
        pass

    if startrow is None:
        startrow = 0

    # write out the new sheet
    df.to_excel(writer, sheet_name, startrow=startrow, **to_excel_kwargs)

    # save the workbook
    writer.save()

用法示例：

filename = r'C:\OCC.xlsx'

append_df_to_excel(filename, df)

append_df_to_excel(filename, df, header=None, index=False)

append_df_to_excel(filename, df, sheet_name='Sheet2', index=False)

append_df_to_excel(filename, df, sheet_name='Sheet2', index=False, startrow=25)

Answer 3

我试着读取一个excel，将它放在一个数据帧中，然后将excel中的数据帧与所需的数据帧连接起来。它对我有用。

def append_df_to_excel(df, excel_path):
    df_excel = pd.read_excel(excel_path)
    result = pd.concat([df_excel, df], ignore_index=True)
    result.to_excel(excel_path, index=False)

df = pd.DataFrame({"a":[11,22,33], "b":[55,66,77]})
append_df_to_excel(df, r"<path_to_dir>\<out_name>.xlsx")