Pandas：如何从 dataframe 的特定列中获取每个类别的样本行并保存在单个 csv 中？

Question

Below is the dataframe (df). I want to save the sample of 3 rows from each category of 'country' column. Following is my code but it's not saving based on category. I need single csv having the samples. Please suggest.

data = {'country':['India', 'Nepal', 'Canada', 'USA','India', 'Nepal', 'Canada', 'USA','India', 'Nepal', 'Canada', 'USA','India', 'Nepal', 'Canada', 'USA','India', 'Nepal', 'Canada', 'USA'],
    'Age':[20, 21, 19, 18,20, 21, 19, 18,20, 21, 19, 18,20, 21, 19, 18,20, 21, 19, 18]}
df = pd.DataFrame(data)

df.sample(n=3).to_csv(sampledata.csv, na_rep='NA', index = False)

Answer 1

GroupBy and then sample

df.groupby('country').sample(3)

   country  Age
2   Canada   19
6   Canada   19
10  Canada   19
4    India   20
0    India   20
12   India   20
1    Nepal   21
13   Nepal   21
9    Nepal   21
3      USA   18
11     USA   18
19     USA   18