引例：
R 茎叶图
data <- c(1, 35, 57, 40, 73, 82, 68, 69, 52, 1, 23, 35, 55, 65, 48, 93, 59, 87, 2, 64)
stem(data)
1、python 实现
from itertools import groupby
data = (1, 35, 57, 40, 73, 82, 68, 69, 52, 1, 23, 35, 55, 65, 48, 93, 59, 87, 2, 64)
data = sorted([str(e) for e in data]) # 数据转换
# k 和 h 分别为每个数值的十位数字和个位数字的字符形式
for k, g in groupby(data, key=lambda x: int(x) // 10):
lst = map(str, [int(h) % 10 for h in list(g)])
print (k, \'|\', \' \'.join(lst))
效果：
