When Update a field: ValueError: Must have equal len keys and value when setting with an iterable-CodePudding

I have a Pandas DataFrame as follows:

import pandas as pd

data = [['tom', 10], ['nick', 15], ['juli', 14]]

df = pd.DataFrame(data, columns=['Name', 'keys'])

When I want to change the value of keys by follows:

df = pd.DataFrame(data, columns=['Name', 'keys'])
df.loc[0, 'keys'] = [540, 12]

It throws an error:

ValueError: Must have equal len keys and value when setting with an iterable

I don't know what the problem is.

CodePudding user response：

I am assuming you want to go from this dataframe :

   name  keywords
0  name1       k1

To this one :

   name       keywords
0  name1  [k1, k2, k3]

Which is what I obtain writing this code :

import pandas as pd

my_dataframe=pd.DataFrame({
    'name': 'name1',
    'keywords':['k1']
})

new_keywords = ['k1', 'k2', 'k3']

my_dataframe.loc[0, 'keywords'] = new_keywords

Tell me if I misunderstood anything.

CodePudding user response：

So, to answer the edited problem :

I think the error comes from the fact that you are trying to replace an int by a table and Pandas doesn't like this. If your input data is a table at the beginning, the error does not appear anymore

Then if you try to replace the line data = [['tom', 10], ['nick', 15], ['juli', 14]] by this one : data = [['tom', [10]], ['nick', [15]], ['juli', [14]]], it should work.