Writing string to empty dataframe not working, but works in other dataframes, how to fix?

Question

I have created a dataframe on my local machine like so:

df1 = pd.DataFrame()

Next, I have added to columns to dataframe plus I want to assign a string to only one column. I am attempting to do this like so:

df1['DF_Name'] = 'test'
df1['DF_Date'] = ''

The columns get added successfully, but the string 'test' does not. When I apply this to other dataframe it works perfectly fine. What am I doing wrong?

I am also trying to append dates into the same dataframe except using logic, and that is also not working. Logic is as so:

if max_created > max_updated:
    df1['DF_Date'] = max_created
else:
    df1['DF_Date'] = max_updated

Not sure what I am doing wrong.

Thank you in advance.

laurenz · Accepted Answer · 2018-02-22 20:04:18Z

1

You need to add brackets, like:

df1 = pd.DataFrame()
df1['DF_Name'] = ['test']
df1['DF_Date'] = ['']
df1

you can't assign a single value to a pd.Series. With the brackets, it's a list instead.

answered Feb 22, 2018 at 20:04

laurenz

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2 Comments

RustyShackleford Over a year ago

why do you need the brackets?

laurenz Over a year ago

with the brackets, it's a list with a string in it, not a string anymore. Try: type(['Hello']) and type('Hello') to see the difference.

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