Python pandas insert list into a cell

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I have a list "abc" and a dataframe "df":

abc = ["foo", "bar"]
df =
    A  B
0  12  NaN
1  23  NaN

I want to insert the list into cell 1B, so I want this result:

    A  B
0  12  NaN
1  23  ["foo", "bar"]

Ho can I do that?

1) If I use this:

df.ix[1,"B"] = abc

I get the following error message:

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

because it tries to insert the list (that has two elements) into a row / column but not into a cell.

2) If I use this:

df.ix[1,"B"] = [abc]

then it inserts a list that has only one element that is the "abc" list ( [["foo", "bar"]] ).

3) If I use this:

df.ix[1,"B"] = ", ".join(abc)

then it inserts a string: ( foo, bar ) but not a list.

4) If I use this:

df.ix[1,"B"] = [", ".join(abc)]

then it inserts a list but it has only one element ( ["foo, bar"] ) but not two as I want ( ["foo", "bar"] ).

Thanks for help!

---

EDIT

My new dataframe and the old list:

abc = ["foo", "bar"]
df2 =
    A    B         C
0  12  NaN      "bla"
1  23  NaN  "bla bla"

Another dataframe:

df3 =
    A    B         C                    D
0  12  NaN      "bla"  ["item1", "item2"]
1  23  NaN  "bla bla"        [11, 12, 13]

I want insert the "abc" list into df2.loc[1,"B"] and/or df3.loc[1,"B"].

If the dataframe has columns only with integer values and/or NaN values and/or list values then inserting a list into a cell works perfectly. If the dataframe has columns only with string values and/or NaN values and/or list values then inserting a list into a cell works perfectly. But if the dataframe has columns with integer and string values and other columns then the error message appears if I use this: df2.loc[1,"B"] = abc or df3.loc[1,"B"] = abc.

Another dataframe:

df4 =
          A     B
0      "bla"  NaN
1  "bla bla"  NaN

These inserts work perfectly: df.loc[1,"B"] = abc or df4.loc[1,"B"] = abc.

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