使用 python pandas 将现有的 excel 表附加到新的数据框

2022-01-22 00:00:00 python pandas excel append for-loop

问题描述

我目前有这个代码.效果很好.

它遍历文件夹中的 excel 文件,删除前 2 行,然后将它们保存为单独的 excel 文件,它还将循环中的文件保存为附加文件.

当前每次运行代码时,附加文件覆盖现有文件.

我需要将新数据追加到已经存在的excel表格('master_data.xlsx)

的底部

dfList = []路径 = 'C:\Test\TestRawFile'newpath = 'C:\Path\To\New\Folder'对于 os.listdir(path) 中的 fn:# 绝对文件路径文件 = os.path.join(路径,fn)如果 os.path.isfile(file):# 导入excel文件并命名为xlsx_filexlsx_file = pd.ExcelFile(文件)# 查看excel文件工作表名称xlsx_file.sheet_names# 加载 xlsx 文件数据表作为数据框df = xlsx_file.parse('Sheet1',header= None)df_NoHeader = df[2:]数据 = df_NoHeader# 保存单个数据框data.to_excel(os.path.join(newpath, fn))dfList.append(数据)appended_data = pd.concat(dfList)appended_data.to_excel(os.path.join(newpath, 'master_data.xlsx'))

我认为这将是一项简单的任务,但我想不会.我想我需要将 master_data.xlsx 文件作为数据框引入,然后将索引与新的附加数据匹配,然后将其保存回来.或者也许有更简单的方法.任何帮助表示赞赏.

解决方案


更新 [2022-01-08]:似乎从 1.4.0 版开始,Pandas 将支持开箱即用"附加到现有 Excel 工作表!

熊猫团队干得好!

根据

PS 如果您不想重复列名,您可能还需要指定 header=None...

更新:您可能还想查看这个旧解决方案

I currently have this code. It works perfectly.

It loops through excel files in a folder, removes the first 2 rows, then saves them as individual excel files, and it also saves the files in the loop as an appended file.

Currently the appended file overwrites the existing file each time I run the code.

I need to append the new data to the bottom of the already existing excel sheet ('master_data.xlsx)

dfList = []
path = 'C:\Test\TestRawFile' 
newpath = 'C:\Path\To\New\Folder'

for fn in os.listdir(path): 
  # Absolute file path
  file = os.path.join(path, fn)
  if os.path.isfile(file): 
    # Import the excel file and call it xlsx_file 
    xlsx_file = pd.ExcelFile(file) 
    # View the excel files sheet names 
    xlsx_file.sheet_names 
    # Load the xlsx files Data sheet as a dataframe 
    df = xlsx_file.parse('Sheet1',header= None) 
    df_NoHeader = df[2:] 
    data = df_NoHeader 
    # Save individual dataframe
    data.to_excel(os.path.join(newpath, fn))

    dfList.append(data) 

appended_data = pd.concat(dfList)
appended_data.to_excel(os.path.join(newpath, 'master_data.xlsx'))

I thought this would be a simple task, but I guess not. I think I need to bring in the master_data.xlsx file as a dataframe, then match the index up with the new appended data, and save it back out. Or maybe there is an easier way. Any Help is appreciated.

解决方案


UPDATE [2022-01-08]: it seems starting from version 1.4.0 Pandas will support appending to existing Excel sheet "out of the box"!

Good job Pandas Team!

According to the DocString in pandas-dev github, ExcelWriter will support parameter if_sheet_exists='overlay'

if_sheet_exists : {'error', 'new', 'replace', 'overlay'}, default 'error'
    How to behave when trying to write to a sheet that already
    exists (append mode only).
    * error: raise a ValueError.
    * new: Create a new sheet, with a name determined by the engine.
    * replace: Delete the contents of the sheet before writing to it.
    * overlay: Write contents to the existing sheet without removing the old
      contents.
    .. versionadded:: 1.3.0
    .. versionchanged:: 1.4.0
       Added ``overlay`` option


For Pandas versions < 1.4.0 please find below a helper function for appending a Pandas DataFrame to an existing Excel file.

If an Excel file doesn't exist then it will be created.


UPDATE [2021-09-12]: fixed for Pandas 1.3.0+

The following functions have been tested with:

  • Pandas 1.3.2
  • OpenPyxl 3.0.7

from pathlib import Path
from copy import copy
from typing import Union, Optional
import numpy as np
import pandas as pd
import openpyxl
from openpyxl import load_workbook
from openpyxl.utils import get_column_letter


def copy_excel_cell_range(
        src_ws: openpyxl.worksheet.worksheet.Worksheet,
        min_row: int = None,
        max_row: int = None,
        min_col: int = None,
        max_col: int = None,
        tgt_ws: openpyxl.worksheet.worksheet.Worksheet = None,
        tgt_min_row: int = 1,
        tgt_min_col: int = 1,
        with_style: bool = True
) -> openpyxl.worksheet.worksheet.Worksheet:
    """
    copies all cells from the source worksheet [src_ws] starting from [min_row] row
    and [min_col] column up to [max_row] row and [max_col] column
    to target worksheet [tgt_ws] starting from [tgt_min_row] row
    and [tgt_min_col] column.

    @param src_ws:  source worksheet
    @param min_row: smallest row index in the source worksheet (1-based index)
    @param max_row: largest row index in the source worksheet (1-based index)
    @param min_col: smallest column index in the source worksheet (1-based index)
    @param max_col: largest column index in the source worksheet (1-based index)
    @param tgt_ws:  target worksheet.
                    If None, then the copy will be done to the same (source) worksheet.
    @param tgt_min_row: target row index (1-based index)
    @param tgt_min_col: target column index (1-based index)
    @param with_style:  whether to copy cell style. Default: True

    @return: target worksheet object
    """
    if tgt_ws is None:
        tgt_ws = src_ws

    # https://stackoverflow.com/a/34838233/5741205
    for row in src_ws.iter_rows(min_row=min_row, max_row=max_row,
                                min_col=min_col, max_col=max_col):
        for cell in row:
            tgt_cell = tgt_ws.cell(
                row=cell.row + tgt_min_row - 1,
                column=cell.col_idx + tgt_min_col - 1,
                value=cell.value
            )
            if with_style and cell.has_style:
                # tgt_cell._style = copy(cell._style)
                tgt_cell.font = copy(cell.font)
                tgt_cell.border = copy(cell.border)
                tgt_cell.fill = copy(cell.fill)
                tgt_cell.number_format = copy(cell.number_format)
                tgt_cell.protection = copy(cell.protection)
                tgt_cell.alignment = copy(cell.alignment)
    return tgt_ws


def append_df_to_excel(
        filename: Union[str, Path],
        df: pd.DataFrame,
        sheet_name: str = 'Sheet1',
        startrow: Optional[int] = None,
        max_col_width: int = 30,
        autofilter: bool = False,
        fmt_int: str = "#,##0",
        fmt_float: str = "#,##0.00",
        fmt_date: str = "yyyy-mm-dd",
        fmt_datetime: str = "yyyy-mm-dd hh:mm",
        truncate_sheet: bool = False,
        storage_options: Optional[dict] = None,
        **to_excel_kwargs
) -> None:
    """
    Append a DataFrame [df] to existing Excel file [filename]
    into [sheet_name] Sheet.
    If [filename] doesn't exist, then this function will create it.

    @param filename: File path or existing ExcelWriter
                     (Example: '/path/to/file.xlsx')
    @param df: DataFrame to save to workbook
    @param sheet_name: Name of sheet which will contain DataFrame.
                       (default: 'Sheet1')
    @param 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...
    @param max_col_width: maximum column width in Excel. Default: 40
    @param autofilter: boolean - whether add Excel autofilter or not. Default: False
    @param fmt_int: Excel format for integer numbers
    @param fmt_float: Excel format for float numbers
    @param fmt_date: Excel format for dates
    @param fmt_datetime: Excel format for datetime's
    @param truncate_sheet: truncate (remove and recreate) [sheet_name]
                           before writing DataFrame to Excel file
    @param storage_options: dict, optional
        Extra options that make sense for a particular storage connection, e.g. host, port,
        username, password, etc., if using a URL that will be parsed by fsspec, e.g.,
        starting "s3://", "gcs://".
    @param to_excel_kwargs: arguments which will be passed to `DataFrame.to_excel()`
                            [can be a dictionary]
    @return: None

    Usage examples:

    >>> append_df_to_excel('/tmp/test.xlsx', df, autofilter=True,
                           freeze_panes=(1,0))

    >>> append_df_to_excel('/tmp/test.xlsx', df, header=None, index=False)

    >>> append_df_to_excel('/tmp/test.xlsx', df, sheet_name='Sheet2',
                           index=False)

    >>> append_df_to_excel('/tmp/test.xlsx', df, sheet_name='Sheet2',
                           index=False, startrow=25)

    >>> append_df_to_excel('/tmp/test.xlsx', df, index=False,
                           fmt_datetime="dd.mm.yyyy hh:mm")

    (c) [MaxU](https://stackoverflow.com/users/5741205/maxu?tab=profile)
    """
    def set_column_format(ws, column_letter, fmt):
        for cell in ws[column_letter]:
            cell.number_format = fmt
    filename = Path(filename)
    file_exists = filename.is_file()
    # process parameters
    # calculate first column number
    # if the DF will be written using `index=True`, then `first_col = 2`, else `first_col = 1`
    first_col = int(to_excel_kwargs.get("index", True)) + 1
    # ignore [engine] parameter if it was passed
    if 'engine' in to_excel_kwargs:
        to_excel_kwargs.pop('engine')
    # save content of existing sheets
    if file_exists:
        wb = load_workbook(filename)
        sheet_names = wb.sheetnames
        sheet_exists = sheet_name in sheet_names
        sheets = {ws.title: ws for ws in wb.worksheets}

    with pd.ExcelWriter(
        filename.with_suffix(".xlsx"),
        engine="openpyxl",
        mode="a" if file_exists else "w",
        if_sheet_exists="new" if file_exists else None,
        date_format=fmt_date,
        datetime_format=fmt_datetime,
        storage_options=storage_options
    ) as writer:
        if file_exists:
            # try to open an existing workbook
            writer.book = wb
            # 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 = sheets
        else:
            # file doesn't exist, we are creating a new one
            startrow = 0

        # write out the DataFrame to an ExcelWriter
        df.to_excel(writer, sheet_name=sheet_name, **to_excel_kwargs)
        worksheet = writer.sheets[sheet_name]

        if autofilter:
            worksheet.auto_filter.ref = worksheet.dimensions

        for xl_col_no, dtyp in enumerate(df.dtypes, first_col):
            col_no = xl_col_no - first_col
            width = max(df.iloc[:, col_no].astype(str).str.len().max(),
                        len(df.columns[col_no]) + 6)
            width = min(max_col_width, width)
            column_letter = get_column_letter(xl_col_no)
            worksheet.column_dimensions[column_letter].width = width
            if np.issubdtype(dtyp, np.integer):
                set_column_format(worksheet, column_letter, fmt_int)
            if np.issubdtype(dtyp, np.floating):
                set_column_format(worksheet, column_letter, fmt_float)

    if file_exists and sheet_exists:
        # move (append) rows from new worksheet to the `sheet_name` worksheet
        wb = load_workbook(filename)
        # retrieve generated worksheet name
        new_sheet_name = set(wb.sheetnames) - set(sheet_names)
        if new_sheet_name:
            new_sheet_name = list(new_sheet_name)[0]
        # copy rows written by `df.to_excel(...)` to
        copy_excel_cell_range(
            src_ws=wb[new_sheet_name],
            tgt_ws=wb[sheet_name],
            tgt_min_row=startrow + 1,
            with_style=True
        )
        # remove new (generated by Pandas) worksheet
        del wb[new_sheet_name]
        wb.save(filename)
        wb.close()


Old version (tested with Pandas 1.2.3 and Openpyxl 3.0.5):

import os
from openpyxl import load_workbook


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.

    @param filename: File path or existing ExcelWriter
                     (Example: '/path/to/file.xlsx')
    @param df: DataFrame to save to workbook
    @param sheet_name: Name of sheet which will contain DataFrame.
                       (default: 'Sheet1')
    @param 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...
    @param truncate_sheet: truncate (remove and recreate) [sheet_name]
                           before writing DataFrame to Excel file
    @param to_excel_kwargs: arguments which will be passed to `DataFrame.to_excel()`
                            [can be a dictionary]
    @return: None

    Usage examples:

    >>> append_df_to_excel('d:/temp/test.xlsx', df)

    >>> append_df_to_excel('d:/temp/test.xlsx', df, header=None, index=False)

    >>> append_df_to_excel('d:/temp/test.xlsx', df, sheet_name='Sheet2',
                           index=False)

    >>> append_df_to_excel('d:/temp/test.xlsx', df, sheet_name='Sheet2', 
                           index=False, startrow=25)

    (c) [MaxU](https://stackoverflow.com/users/5741205/maxu?tab=profile)
    """
    # Excel file doesn't exist - saving and exiting
    if not os.path.isfile(filename):
        df.to_excel(
            filename,
            sheet_name=sheet_name, 
            startrow=startrow if startrow is not None else 0, 
            **to_excel_kwargs)
        return
    
    # ignore [engine] parameter if it was passed
    if 'engine' in to_excel_kwargs:
        to_excel_kwargs.pop('engine')

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

    # 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}

    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()


Usage examples:

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)


c:/temp/test.xlsx:

PS you may also want to specify header=None if you don't want to duplicate column names...

UPDATE: you may also want to check this old solution

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