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How to read multiple csv files with specific name from a folder and merge them?

I am trying to read multiple files from a folder with specific name (1.car.csv, 2.car.csv and so on) and trying to add a new label after each iteration at right most of the dataset and merge all the csv files into one csv file. As the ".car.csv" is constant, I think I can use a for loop with .format(index) function to run over the csv files. All of the csv files has got same attributes.
Kindly help me!

glob is used to get all files in the folder that match the pattern *.csv
pd.read_csv is used to read each file as a DataFrame
index_col=None you are telling Pandas to not use any of the columns as the index, and instead to create a default index for the DataFrame.
header=0 you are telling Pandas to use the first row of the CSV file as the header row.
pd.concat is used to merge all the DataFrames into a single DataFrame merged_df
axis=0 means that the concatenation should happen along the rows (vertically)
ignore_index=True the concatenation is performed such that the original indices of the individual DataFrames are discarded, and a new default index is created for the resulting DataFrame.
import glob
import pandas as pd
path = r'<path to folder containing csv files>'
all_files = glob.glob(path + "/*.csv")
lst = []
for filename in all_files:
df = pd.read_csv(filename, index_col=None, header=0)
lst.append(df)
merged_df = pd.concat(lst, axis=0, ignore_index=True)

This can be easily done with a CSV tool like miller:
mlr --csv cat --filename bla1.csv *.car.csv
This will concatenate the files (without repeating the header) and prepend the filename as the first column.

You can use the pandas library this way:
import pandas as pd
import os
# path to folder where the csv files are stored
path = '/path/to/folder'
result = pd.DataFrame()
for i in range(1, n+1):
filename = "{}.car.csv".format(i)
file_path = os.path.join(path, filename)
df = pd.read_csv(file_path)
df['new_label'] = i
result = pd.concat([result, df], ignore_index=True)
result.to_csv('final_result.csv', index=False)
The n in the code above should be replaced with the number of csv files you have in the folder.
If you need any explanation of the code (in case you're new to python or dataframes) just comment below.

Using pathlib and pandas you can use .assign() to enter the new column and finally .concat() to concatenate all the files into one.
from pathlib import Path
import pandas as pd
input_path = Path("path/to/car/files/").glob("*car.csv")
output_path = "path/to/output"
pd.concat(
(pd.read_csv(x).assign(new_label="new data") for x in input_path), ignore_index=True
).to_csv(f"{output_path}/final.csv", index=False)

Pandas Only Exporting 1 Table to Excel but Printing all

The code below only exports the last table on the page to excel, but when I run the print function, it will print all of them. Is there an issue with my code causing not to export all data to excel?
I've also tried exporting as .csv file with no luck.
import pandas as pd
url = 'https://www.vegasinsider.com/college-football/matchups/'
dfs = pd.read_html(url)
for df in dfs:
if len(df.columns) > 1:
df.to_excel(r'VegasInsiderCFB.xlsx', index = False)
#print(df)

Your problem is that each time df.to_excel is called, you are overwriting the file, so only the last df will be left. What you need to do is use a writer and specify a sheet name for each separate df e.g:
url = 'https://www.vegasinsider.com/college-football/matchups/'
writer = pd.ExcelWriter('VegasInsiderCFB.xlsx', engine='xlsxwriter')
dfs = pd.read_html(url)
counter = 0
for df in dfs:
if len(df.columns) > 4:
counter += 1
df.to_excel(writer, sheet_name = f"sheet_{counter}", index = False)
writer.save()
You might need pip install xlsxwriter xlwt to make it work.
Exporting to a csv will never work, since a csv is a single data table (like a single sheet in excel), so in that case you would need to use a new csv for each df.
As pointed out in the comments, it would be possible to write the data onto a single sheet without changing the dfs, but it is likely much better to merge them:
import pandas as pd
import numpy as np
url = 'https://www.vegasinsider.com/college-football/matchups/'
dfs = pd.read_html(url)
dfs = [df for df in dfs if len(df.columns) > 4]
columns = ["gameid","game time", "team"] + list(dfs[0].iloc[1])[1:]
N = len(dfs)
values = np.empty((2*N,len(columns)),dtype=np.object)
for i,df in enumerate(dfs):
time = df.iloc[0,0].replace(" Game Time","")
values[2*i:2*i+2,2:] = df.iloc[2:,:]
values[2*i:2*i+2,:2] = np.array([[i,time],[i,time]])
newdf = pd.DataFrame(values,columns = columns)
newdf.to_excel("output.xlsx",index = False)
I used a numpy.array of object type to be able to copy a submatrix from the original dataframes easily into their intended place. I also needed to create a gameid, that connects the games across rows. It should be now trivial to rewrite this so you loop through a list of urls and write these to separate sheets.

Read multiple sheets in multiple excel files using pandas

I am trying to make a list using pandas before putting all data sets into 2D convolution layers.
And I was able to merge all data in the multiple excel files as a list.
However, the code only reads one chosen sheet name in the multiple excel files.
For example, I have 7 sheets in each excel file; named as 'gpascore1', 'gpascore2', 'gpascore3', 'gpascore4', 'gpascore5', 'gpascore6', 'gpascore7'.
And each sheet has 4 rows and 425 columns like
As shown below, you can see the code.
import os
import pandas as pd
path = os.getcwd()
files = os.listdir(path)
files_xls = [f for f in files if f[-3:] == 'xls']
df = pd.DataFrame()
for f in files_xls:
data = pd.read_excel(f, 'gpascore1') # Read only one chosen sheet available ->
gpascore1 is a sheet name.
df = df.append(data) # But there are 6 more sheets and I would like
to read data from all of the sheets
data_y = df['admit'].values
data_x = []
for i, rows in df.iterrows():
data_x.append([rows['gre'], rows['gpa'], rows['rank']])
df=df.dropna()
df.count()
Then, I got the result as below.
This is because the data from the 'gpascore1' sheet in 3 excel files were merged.
But, I want to read the data of 6 more sheets in the excel files.
Could anyone help me to find out the answer, please?
Thank you
===============<Updated code & errors>==================================
Thank you for the answers and I revised the read_excel() as
data = pd.read_excel(f, 'gpascore1') to
data = pd.read_excel(f, sheet_name=None)
But, I have key errors like below.
Could you give me any suggestions for this issue, please?
Thank you

I actually found this question under the tag of 'tensorflow'. That's hilarious. Ok, so you want to merge all Excel sheets into one dataframe?
import os
import pandas as pd
import glob
glob.glob("C:\\your_path\\*.xlsx")
all_data = pd.DataFrame()
for f in glob.glob("C:\\your_path\\*.xlsx"):
df = pd.read_excel(f)
all_data = all_data.append(df,ignore_index=True)
type(all_data)

When compiling multiple excel files into csv files, datetime turns into integer dtype

I'm using python to merge some excel files into a single csv file, but when doing so, the datetimes get turned into integers. So, when I read it back with pandas to treat my unified database, I would need to convert it back to datetime, which is possible but seems unnecessary. The code for reading and compiling the files:
folder = Path('myPath')
os.chdir(folder)
files = sorted(os.listdir(os.getcwd()), key = os.path.getctime)
for file in files:
with xlrd.open_workbook(folder/file) as wb:
sh = wb.sheet_by_index(0)
with open('Unified database.csv', 'wb') as f:
c = csv.writer(f, encoding = 'utf-8')
for r in range(sh.nrows):
c.writerow(sh.row_values(r))
Is there a way to take less steps into solving this problem, and just write the datetime columns as strings, which pandas has a much easier time automatically identifying as dates? Even if I have to pass the datetime columns manually.

Have you tried to read all of the excel files directly into a pandas dataframe? The code below is from this answer on how to Import multiple csv files into pandas and concatenate into one DataFrame. I have added the dtype so you can specify which columns should be datetime.
import pandas as pd
import glob
path = r'C:\DRO\DCL_rawdata_files' # use your path
all_files = glob.glob(path + "/*.xlsx")
li = []
for filename in all_files:
df = pd.read_xlsx(filename, index_col=None, header=0, dtype={‘a’: np.datetime})
li.append(df)
frame = pd.concat(li, axis=0, ignore_index=True)

How to concatenate three excels files xlsx using python?

Hello I would like to concatenate three excels files xlsx using python.
I have tried using openpyxl, but I don't know which function could help me to append three worksheet into one.
Do you have any ideas how to do that ?
Thanks a lot

Here's a pandas-based approach. (It's using openpyxl behind the scenes.)
import pandas as pd
# filenames
excel_names = ["xlsx1.xlsx", "xlsx2.xlsx", "xlsx3.xlsx"]
# read them in
excels = [pd.ExcelFile(name) for name in excel_names]
# turn them into dataframes
frames = [x.parse(x.sheet_names[0], header=None,index_col=None) for x in excels]
# delete the first row for all frames except the first
# i.e. remove the header row -- assumes it's the first
frames[1:] = [df[1:] for df in frames[1:]]
# concatenate them..
combined = pd.concat(frames)
# write it out
combined.to_excel("c.xlsx", header=False, index=False)

I'd use xlrd and xlwt. Assuming you literally just need to append these files (rather than doing any real work on them), I'd do something like: Open up a file to write to with xlwt, and then for each of your other three files, loop over the data and add each row to the output file. To get you started:
import xlwt
import xlrd
wkbk = xlwt.Workbook()
outsheet = wkbk.add_sheet('Sheet1')
xlsfiles = [r'C:\foo.xlsx', r'C:\bar.xlsx', r'C:\baz.xlsx']
outrow_idx = 0
for f in xlsfiles:
# This is all untested; essentially just pseudocode for concept!
insheet = xlrd.open_workbook(f).sheets()[0]
for row_idx in xrange(insheet.nrows):
for col_idx in xrange(insheet.ncols):
outsheet.write(outrow_idx, col_idx,
insheet.cell_value(row_idx, col_idx))
outrow_idx += 1
wkbk.save(r'C:\combined.xls')
If your files all have a header line, you probably don't want to repeat that, so you could modify the code above to look more like this:
firstfile = True # Is this the first sheet?
for f in xlsfiles:
insheet = xlrd.open_workbook(f).sheets()[0]
for row_idx in xrange(0 if firstfile else 1, insheet.nrows):
pass # processing; etc
firstfile = False # We're done with the first sheet.

When I combine excel files (mydata1.xlsx, mydata2.xlsx, mydata3.xlsx) for data analysis, here is what I do:
import pandas as pd
import numpy as np
import glob
all_data = pd.DataFrame()
for f in glob.glob('myfolder/mydata*.xlsx'):
df = pd.read_excel(f)
all_data = all_data.append(df, ignore_index=True)
Then, when I want to save it as one file:
writer = pd.ExcelWriter('mycollected_data.xlsx', engine='xlsxwriter')
all_data.to_excel(writer, sheet_name='Sheet1')
writer.save()

Solution with openpyxl only (without a bunch of other dependencies).
This script should take care of merging together an arbitrary number of xlsx documents, whether they have one or multiple sheets. It will preserve the formatting.
There's a function to copy sheets in openpyxl, but it is only from/to the same file. There's also a function insert_rows somewhere, but by itself it won't insert any rows. So I'm afraid we are left to deal (tediously) with one cell at a time.
As much as I dislike using for loops and would rather use something compact and elegant like list comprehension, I don't see how to do that here as this is a side-effect show.
Credit to this answer on copying between workbooks.
#!/usr/bin/env python3
#USAGE
#mergeXLSX.py <a bunch of .xlsx files> ... output.xlsx
#
#where output.xlsx is the unified file
#This works FROM/TO the xlsx format. Libreoffice might help to convert from xls.
#localc --headless --convert-to xlsx somefile.xls
import sys
from copy import copy
from openpyxl import load_workbook,Workbook
def createNewWorkbook(manyWb):
for wb in manyWb:
for sheetName in wb.sheetnames:
o = theOne.create_sheet(sheetName)
safeTitle = o.title
copySheet(wb[sheetName],theOne[safeTitle])
def copySheet(sourceSheet,newSheet):
for row in sourceSheet.rows:
for cell in row:
newCell = newSheet.cell(row=cell.row, column=cell.col_idx,
value= cell.value)
if cell.has_style:
newCell.font = copy(cell.font)
newCell.border = copy(cell.border)
newCell.fill = copy(cell.fill)
newCell.number_format = copy(cell.number_format)
newCell.protection = copy(cell.protection)
newCell.alignment = copy(cell.alignment)
filesInput = sys.argv[1:]
theOneFile = filesInput.pop(-1)
myfriends = [ load_workbook(f) for f in filesInput ]
#try this if you are bored
#myfriends = [ openpyxl.load_workbook(f) for k in range(200) for f in filesInput ]
theOne = Workbook()
del theOne['Sheet'] #We want our new book to be empty. Thanks.
createNewWorkbook(myfriends)
theOne.save(theOneFile)
Tested with openpyxl 2.5.4, python 3.4.

You can simply use pandas and os library to do this.
import pandas as pd
import os
#create an empty dataframe which will have all the combined data
mergedData = pd.DataFrame()
for files in os.listdir():
#make sure you are only reading excel files
if files.endswith('.xlsx'):
data = pd.read_excel(files, index_col=None)
mergedData = mergedData.append(data)
#move the files to other folder so that it does not process multiple times
os.rename(files, 'path to some other folder')
mergedData DF will have all the combined data which you can export in a separate excel or csv file. Same code will work with csv files as well. just replace it in the IF condition

Just to add to p_barill's answer, if you have custom column widths that you need to copy, you can add the following to the bottom of copySheet:
for col in sourceSheet.column_dimensions:
newSheet.column_dimensions[col] = sourceSheet.column_dimensions[col]
I would just post this in a comment on his or her answer but my reputation isn't high enough.