Python Pandas dataframe how to add an integer to each element in a column of lists-CodePudding

If I have a pandas dataframe like this

d = {'id': {0: 0, 1: 1, 2: 2.0, 3: 3},
 'lst': {0: [1, 2], 1: [0], 2: [1, 2, 3], 3: np.nan}}
df = pd.DataFrame(d)
print(df)

    id        lst
0  0.0     [1, 2]
1  1.0        [0]
2  2.0  [1, 2, 3]
3  3.0        NaN

How can I add 1 to each element of the lists, Nan will remain to be Nan. So the output should be like this:

    id        lst
0  0.0     [2, 3]
1  1.0        [1]
2  2.0  [2, 3, 4]
3  3.0        NaN

Thanks!

CodePudding user response：

IIUC, try mapping to numpy array and add 1 else you can use apply and add 1:

df['lst'] = df['lst'].map(np.array).add(1)

CodePudding user response：

You could use map() with list comprehensions and na_action parameter

df['lst'].map(lambda x: [i 1 for i in x],na_action='ignore')

Output:

0       [2, 3]
1          [1]
2    [2, 3, 4]
3          NaN

CodePudding user response：

Using a classical list comprehension:

df['lst'] = [[x 1 for x in l] if isinstance(l, list) else l
             for l in df['lst']]

Output:

    id        lst
0  0.0     [2, 3]
1  1.0        [1]
2  2.0  [2, 3, 4]
3  3.0        NaN