如何使用 Pandas 在现有 excel 文件中保存新的 sheet？

Question

我想使用 excel 文件来存储用 python 详细说明的数据。我的问题是我无法将工作表添加到现有 excel 文件。在这里，我建议使用一个示例代码来解决这个问题

import pandas as pd
import numpy as np

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"

x1 = np.random.randn(100, 2)
df1 = pd.DataFrame(x1)

x2 = np.random.randn(100, 2)
df2 = pd.DataFrame(x2)

writer = pd.ExcelWriter(path, engine = 'xlsxwriter')
df1.to_excel(writer, sheet_name = 'x1')
df2.to_excel(writer, sheet_name = 'x2')
writer.save()
writer.close()

此代码将两个 DataFrame 保存到两个工作表中，分别命名为 "x1" 和 "x2"。如果我创建两个新的 DataFrame 并尝试使用相同的代码添加两个新工作表 'x3' 和 'x4'，则原始数据将丢失。

import pandas as pd
import numpy as np

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"

x3 = np.random.randn(100, 2)
df3 = pd.DataFrame(x3)

x4 = np.random.randn(100, 2)
df4 = pd.DataFrame(x4)

writer = pd.ExcelWriter(path, engine = 'xlsxwriter')
df3.to_excel(writer, sheet_name = 'x3')
df4.to_excel(writer, sheet_name = 'x4')
writer.save()
writer.close()

我想要一个包含四张纸的 excel 文件：'x1'、'x2'、'x3'、'x4'。我知道'xlsxwriter'不是唯一的"engine"，还有'openpyxl'。我也看到已经有其他人写过这个问题，但我还是不明白该怎么做。

这里是取自这个 link

的代码

import pandas
from openpyxl import load_workbook

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

data_filtered.to_excel(writer, "Main", cols=['Diff1', 'Diff2'])

writer.save()

他们说它有效，但很难弄清楚它是如何工作的。我不明白 "ws.title"、"ws" 和 "dict" 是什么意思。

保存"x1"和"x2"哪个最好，然后关闭文件，再次打开并添加"x3"和"x4"？

Answer 1

在您分享的示例中，您将现有文件加载到 book 并将 writer.book 值设置为 book。在行 writer.sheets = dict((ws.title, ws) for ws in book.worksheets) 中，您正在以 ws 的形式访问工作簿中的每个 sheet。 sheet 标题然后是 ws 所以你正在创建一个 {sheet_titles: sheet} 键值对的字典。然后将此字典设置为 writer.sheets。 本质上，这些步骤只是从 'Masterfile.xlsx' 加载现有数据并用它们填充您的编写器。

现在假设您已经有一个 x1 和 x2 作为 sheet 的文件。您可以使用示例代码加载文件，然后可以执行类似这样的操作来添加 x3 和 x4。

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"
writer = pd.ExcelWriter(path, engine='openpyxl')
df3.to_excel(writer, 'x3', index=False)
df4.to_excel(writer, 'x4', index=False)
writer.save()

这应该能满足您的需求。

Answer 2

我强烈建议您直接使用 openpyxl since it now supports Pandas DataFrames。

这让您可以专注于相关的 Excel 和 Pandas 代码。

Answer 3

谢谢。我相信一个完整的例子可能对其他有同样问题的人有好处：

import pandas as pd
import numpy as np

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"

x1 = np.random.randn(100, 2)
df1 = pd.DataFrame(x1)

x2 = np.random.randn(100, 2)
df2 = pd.DataFrame(x2)

writer = pd.ExcelWriter(path, engine = 'xlsxwriter')
df1.to_excel(writer, sheet_name = 'x1')
df2.to_excel(writer, sheet_name = 'x2')
writer.save()
writer.close()

这里我生成了一个excel文件，根据我的理解，它是通过"xslxwriter"还是"openpyxl"引擎生成的并不重要。

当我想在不丢失原始数据的情况下写入时

import pandas as pd
import numpy as np
from openpyxl import load_workbook

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"

book = load_workbook(path)
writer = pd.ExcelWriter(path, engine = 'openpyxl')
writer.book = book

x3 = np.random.randn(100, 2)
df3 = pd.DataFrame(x3)

x4 = np.random.randn(100, 2)
df4 = pd.DataFrame(x4)

df3.to_excel(writer, sheet_name = 'x3')
df4.to_excel(writer, sheet_name = 'x4')
writer.save()
writer.close()

此代码可以完成工作！

Answer 4

一次将多个数据写入excel的简单示例。以及当您想将数据附加到写入的 excel 文件（关闭的 excel 文件）上的 sheet 时。

当您第一次写入 excel 时。（将 "df1" 和 "df2" 写入“1st_sheet”和“2nd_sheet”）

import pandas as pd 
from openpyxl import load_workbook

df1 = pd.DataFrame([[1],[1]], columns=['a'])
df2 = pd.DataFrame([[2],[2]], columns=['b'])
df3 = pd.DataFrame([[3],[3]], columns=['c'])

excel_dir = "my/excel/dir"

with pd.ExcelWriter(excel_dir, engine='xlsxwriter') as writer:    
    df1.to_excel(writer, '1st_sheet')   
    df2.to_excel(writer, '2nd_sheet')   
    writer.save()

在您关闭 excel 之后，但您希望 "append" 数据在同一个 excel 文件中，但另一个 sheet，假设 "df3" sheet 名称“3rd_sheet”。

book = load_workbook(excel_dir)
with pd.ExcelWriter(excel_dir, engine='openpyxl') as writer:
    writer.book = book
    writer.sheets = dict((ws.title, ws) for ws in book.worksheets)    

    ## Your dataframe to append. 
    df3.to_excel(writer, '3rd_sheet')  

    writer.save()

注意excel格式不能是xls，可以用xlsx。

Answer 5

您可以将您感兴趣的现有工作表（例如 'x1'、'x2'）读入内存，然后 'write' 在添加更多新工作表之前将其返回（请记住文件中的表格和内存中的表格是两个不同的东西，如果你不阅读它们，它们就会丢失）。此方法仅使用 'xlsxwriter'，不涉及 openpyxl。

import pandas as pd
import numpy as np

path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx"

# begin <== read selected sheets and write them back
df1 = pd.read_excel(path, sheet_name='x1', index_col=0) # or sheet_name=0
df2 = pd.read_excel(path, sheet_name='x2', index_col=0) # or sheet_name=1
writer = pd.ExcelWriter(path, engine='xlsxwriter')
df1.to_excel(writer, sheet_name='x1')
df2.to_excel(writer, sheet_name='x2')
# end ==>

# now create more new sheets
x3 = np.random.randn(100, 2)
df3 = pd.DataFrame(x3)

x4 = np.random.randn(100, 2)
df4 = pd.DataFrame(x4)

df3.to_excel(writer, sheet_name='x3')
df4.to_excel(writer, sheet_name='x4')
writer.save()
writer.close()

如果你想保留所有现有的工作表，你可以将上面的开始和结束之间的代码替换为：

# read all existing sheets and write them back
writer = pd.ExcelWriter(path, engine='xlsxwriter')
xlsx = pd.ExcelFile(path)
for sheet in xlsx.sheet_names:
    df = xlsx.parse(sheet_name=sheet, index_col=0)
    df.to_excel(writer, sheet_name=sheet)

Answer 6

#This program is to read from excel workbook to fetch only the URL domain names and write to the existing excel workbook in a different sheet..
#Developer - Nilesh K
import pandas as pd
from openpyxl import load_workbook #for writting to the existing workbook

df = pd.read_excel("urlsearch_test.xlsx")

#You can use the below for the relative path.
# r"C:\Users\xyz\Desktop\Python\

l = [] #To make a list in for loop

#begin
#loop starts here for fetching http from a string and iterate thru the entire sheet. You can have your own logic here.
for index, row in df.iterrows():
    try: 
        str = (row['TEXT']) #string to read and iterate
        y = (index)
        str_pos = str.index('http') #fetched the index position for http
        str_pos1 = str.index('/', str.index('/')+2) #fetched the second 3rd position of / starting from http
        str_op = str[str_pos:str_pos1] #Substring the domain name
        l.append(str_op) #append the list with domain names

    #Error handling to skip the error rows and continue.
    except ValueError:
            print('Error!')
print(l)
l = list(dict.fromkeys(l)) #Keep distinct values, you can comment this line to get all the values
df1 = pd.DataFrame(l,columns=['URL']) #Create dataframe using the list
#end

#Write using openpyxl so it can be written to same workbook
book = load_workbook('urlsearch_test.xlsx')
writer = pd.ExcelWriter('urlsearch_test.xlsx',engine = 'openpyxl')
writer.book = book
df1.to_excel(writer,sheet_name = 'Sheet3')
writer.save()
writer.close()

#The below can be used to write to a different workbook without using openpyxl
#df1.to_excel(r"C:\Users\xyz\Desktop\Python\urlsearch1_test.xlsx",index='false',sheet_name='sheet1')

Answer 7

另一种相当简单的方法是制作如下方法：

def _write_frame_to_new_sheet(path_to_file=None, sheet_name='sheet', data_frame=None):
    book = None
    try:
        book = load_workbook(path_to_file)
    except Exception:
        logging.debug('Creating new workbook at %s', path_to_file)
    with pd.ExcelWriter(path_to_file, engine='openpyxl') as writer:
        if book is not None:
            writer.book = book
        data_frame.to_excel(writer, sheet_name, index=False)

这里的想法是加载 path_to_file 处的工作簿（如果存在）然后附加 data_frame 作为新的 sheet 和 sheet_name。如果工作簿不存在，则会创建它。似乎 openpyxl 或 xlsxwriter 都没有附加，所以就像上面@Stefano 的例子一样，你真的必须加载然后重写才能附加。

Answer 8

不使用ExcelWriter也可以，使用openpyxl中的工具这可以使用 openpyxl.styles

更轻松地向新的 sheet 添加字体

import pandas as pd
from openpyxl import load_workbook
from openpyxl.utils.dataframe import dataframe_to_rows

#Location of original excel sheet
fileLocation =r'C:\workspace\data.xlsx'

#Location of new file which can be the same as original file
writeLocation=r'C:\workspace\dataNew.xlsx'

data = {'Name':['Tom','Paul','Jeremy'],'Age':[32,43,34],'Salary':[20000,34000,32000]}

#The dataframe you want to add
df = pd.DataFrame(data)

#Load existing sheet as it is
book = load_workbook(fileLocation)
#create a new sheet
sheet = book.create_sheet("Sheet Name")

#Load dataframe into new sheet
for row in dataframe_to_rows(df, index=False, header=True):
    sheet.append(row)

#Save the modified excel at desired location    
book.save(writeLocation)

Answer 9

用于创建新文件

x1 = np.random.randn(100, 2)
df1 = pd.DataFrame(x1)
with pd.ExcelWriter('sample.xlsx') as writer:  
    df1.to_excel(writer, sheet_name='x1')

要附加到文件，请在 pd.ExcelWriter 中使用参数 mode='a'。

x2 = np.random.randn(100, 2)
df2 = pd.DataFrame(x2)
with pd.ExcelWriter('sample.xlsx', engine='openpyxl', mode='a') as writer:  
    df2.to_excel(writer, sheet_name='x2')

默认值为 mode ='w'。参见 documentation。

Answer 10

import pandas as pd
import openpyxl

writer = pd.ExcelWriter('test.xlsx', engine='openpyxl')
data_df.to_excel(writer, 'sheet_name')
writer.save()
writer.close()

Answer 11

每次你想保存一个Pandas DataFrame到一个Excel，你可以调用这个函数：

import os

def save_excel_sheet(df, filepath, sheetname, index=False):
    # Create file if it does not exist
    if not os.path.exists(filepath):
        df.to_excel(filepath, sheet_name=sheetname, index=index)

    # Otherwise, add a sheet. Overwrite if there exists one with the same name.
    else:
        with pd.ExcelWriter(filepath, engine='openpyxl', if_sheet_exists='replace', mode='a') as writer:
            df.to_excel(writer, sheet_name=sheetname, index=index)

Answer 12

如果要加空sheet

xw = pd.ExcelWriter(file_path, engine='xlsxwriter')    
pd.DataFrame().to_excel(xw, 'sheet11')

如果你变空了sheet

sheet = xw.sheets['sheet11']

如何使用 Pandas 在现有 excel 文件中保存新的 sheet？

How to save a new sheet in an existing excel file, using Pandas?

python

pandas

openpyxl

xlsxwriter