how to add a variable in a dictionary with several dataframes?

Question

I have a dictionary with several dataframes that looks like this:

dataframes = {'Df_20100101': DataFrame, 'Df_20100102': DataFrame, 'Df_20100103': DataFrame}

The keyname for each dataframe is composed by Df_ followed by the date 2010 [year], 01[month] and 01[day].

For each dataframe I want to add a new variable/column with the date [of course in the date format] that corresponds to its key.

I am kind of new learning to use dictionaries, so I would be really thankful if you can help me.

I tried with the following code, but it is pretty basic for what I want.

for key, val in  dataframes.items():
 val['Key']==k

Thanks in advance!

Answer 1

You have the right start.

for key, val in dataframes.items():
    *_, date = key.split("_")
    val["Date"] = pd.date_range(start=date, end=date, periods=len(val))

If you want to change the date format, you can do like this.

for key, val in dataframes.items():
    *_, date = key.split("_")
    val["Date"] = pd.date_range(start=date, end=date, periods=len(val)).strftime('%m/%d/%Y') #<==== here 

And the documentation about date format.

Edit :

The aford mentioned awnser is overcomplicating as when you passs a single value in a new column assignement, pandas will automaticly fill the entire column.

See @jezrael awser.

For changing the date format with @jezrael awser, just add format='%m/%d/%Y'.

for key, val in  dataframes.items():
    dataframes[key]['Key'] = pd.to_datetime(key.split('_')[1], format='%m/%d/%Y')