Weird ,0 at top of .csv file while using Pandas with Dictionary-CodePudding

I want to print a dictionary into a csv file. Dictionary is containing a subject code as a key and a mark that one student got as a value.

Here is my .py code:

import pandas as pd

classes = dict()

print('Type STOP to end.\n')

while True:
    key = input('Subject ID: ')
    if key == 'STOP':
        break
    else:
        value = input('Mark: ')
        classes[key] = value

print(classes)

df = pd.DataFrame.from_dict(classes, orient='index')
df.to_csv("student_report.csv")

Code prints the dict:

{'IT255': '10', 'IT335': '9', 'CS324': '10', 'CS225': '7'}

Here is csv file:

,0
IT255,10
IT335,9
CS324,10
CS225,7

I don't know what is causing the ,0 at the top. Any help?

UPDATE

Printing the data frame brings this:

CodePudding user response：

Pandas insists that each column have a title, and it wants to write those column names as the CSV header. Since you didn't provide any column names in your import, pandas assigns names to the columns. The first column is an index, which doesn't need a name. The other columns are assigned names starting with 0. You can supply your own column names with the header parameter to to_csv, or pass header=False to suppress them.

As a side note, if this is ALL you are using pandas for, it would be MUCH more efficient to use the Python csv module. pandas is a very large module that can take multiple second to load. If you don't need its fancy capabilities, just use csv.