用值 Python-Pandas 替换空单元格

Question

I have a csv file that looks like this

col1,col2,col3,col4,col5

value1,value2,value3,value4,value5

,,value6,value7,value8

,,value10,value11,value12

I would need to insert values in the empty cells.

I am reading the data with pandas like this

import pandas as pd

data = pd.read_csv(file).fillna('yellow', 'blue') 

any sugestions?

Update : the error is solved The rows in my csv where an editing mistake. The main problem is how to write in to the empty cells custom values.

Expected result

col1,col2,col3,col4,col5

value1,value2,value3,value4,value5

yellow,blue,value6,value7,value8

yellow,blue,value10,value11,value12

actual result

col1,col2,col3,col4,col5

value1,value2,value3,value4,value5

NaN,NaN,value6,value7,value8

NaN,NaN,value10,value11,value12

Initial problem -> Solved

I am getting an error like this:

pandas.errors.ParserError: Error tokenizing data. C error: Expected 5 fields in line 3, saw 6

Answer 1

You have 2 empty columns in lines 3 and 4. So, that makes it 6 columns but you have 5 headers. Just delete the first comma like this:

,value6,value7,value8,value9

For the second question you can try this:

df['col1'] = df['col1'].fillna('yellow')

Answer 2

The topmost row of your csv file if the headers and it will determine the number of columns in your data. As you have 5 headers,

col1, col2, col 3, col 4, col 5

The csv reader will expect there to be 5 columns in every subsequent row of data. As such, your 3rd and 4th row in your csv will be invalid and unalbe to be read by the csv reader.

Eg. ,,value6,value7,value8,value9 has a total of 6 columns.

Answer 3

This is what I need.

data = pd.read_csv(file)
hello = data.append({'col1': yello, 'col2': 'blue'}, ignore_index=True)

Now I'd need to write it again to the file.