What is the problem with the pandas to csv in my code?

Question

I am running this code for a project I am doing for fun to find patterns in Disneyland wait times:

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
df_pirates_all = pd.read_csv(
    "https://cdn.touringplans.com/datasets/pirates_of_caribbean_dlr.csv",usecols=['date','datetime','SPOSTMIN'],
    parse_dates=['date', 'datetime'], 
)
df_pirates_all['ride'] = 'pirates'
df_pirates_all['open'] = ~((df_pirates_all['SPOSTMIN'] == -999))

df_pirates = df_pirates_all.set_index('datetime').sort_index()
df_pirates = df_pirates.loc['2017-01-01 06:00':'2017-02-01 00:00']
df_pirates = df_pirates.resample('15Min').ffill()


df_star_tours_all = pd.read_csv(
    "https://cdn.touringplans.com/datasets/star_tours_dlr.csv", usecols=['date','datetime','SPOSTMIN'],
    parse_dates=['date', 'datetime']
)
df_star_tours_all['ride'] = 'star_tours'
df_star_tours_all['open'] = ~((df_star_tours_all['SPOSTMIN'] == -999))

df_star_tours = df_star_tours_all.set_index('datetime').sort_index()
df_star_tours = df_star_tours.loc['2017-01-01 06:00':'2017-02-01 00:00']
df_star_tours = df_star_tours.resample('15Min').ffill()

df_space_all = pd.read_csv(
    "https://cdn.touringplans.com/datasets/space_mountain_dlr.csv", usecols=['date','datetime','SPOSTMIN'], 
    parse_dates=['date', 'datetime']
)
df_space_all['ride'] = 'space'
df_space_all['open'] = ~((df_space_all['SPOSTMIN'] == -999))

df_space = df_space_all.set_index('datetime').sort_index()
df_space = df_space.loc['2017-01-01 06:00':'2017-02-01 00:00']
df_space = df_space.resample('15Min').ffill()


all_data = pd.concat([df_pirates, df_star_tours, df_space]).reset_index()
all_data = (
    all_data
        # Drop any "NaN" values in the column 'ride'
        .dropna(subset=['ride', ])
        # Make datetime and ride a "Multi-Index"
        .set_index(['datetime', 'ride'])
        # Choose the column 'SPOSTMIN'
        ['SPOSTMIN']
        # Take the last index ('ride') and rotate to become column names
        .unstack()
)
# print (all_data)

for month, group in all_data.groupby(pd.Grouper(freq='M')):
    with pd.ExcelWriter(f'{month}.xlsx') as writer:
        for day, dfsub in group.groupby(pd.Grouper(freq='D')):
            dfsub.to_excel(writer, sheet_name='day')

However I am running into this error

FileCreateError: [Errno 22] Invalid argument: '2017-01-31 00:00:00.xlsx'

and it is connected to the dfsub.to_excel line.

It mostly got fixed by the comments, however, only one sheet is appearing and it only has the last day of data (1-31-17) instead of individual sheets for 1-1-17,1-2-17,etc.

Answer 1

What got it fixed was changing the code from

for month, group in all_data.groupby(pd.Grouper(freq='M')):
    with pd.ExcelWriter(f'{month}.xlsx') as writer:
        for day, dfsub in group.groupby(pd.Grouper(freq='D')):
            dfsub.to_excel(writer, sheet_name='day')

to

for month, group in all_data.groupby(pd.Grouper(freq='M')):
    with pd.ExcelWriter(f'{month.strftime("%B %Y")}.xlsx') as writer:
        for day, dfsub in group.groupby(pd.Grouper(freq='D')):
            dfsub.to_excel(writer,sheet_name=str(day.date()))

with the suggestions that were made.