df的animal和age列
df.loc[:, ['animal', 'age']]
# 方法二
# df[['animal', 'age']]
10.取出索引为[3, 4, 8]行的animal和...,生成新列y
df = pd.DataFrame({'X': [7, 2, 0, 3, 4, 2, 5, 0, 3, 4]})
izero = np.r_[-1, (df['X'] == 0).to_numpy...= 0).cumsum()
# y = x != x.shift()
# df['Y'] = y.groupby((y !...= y.shift()).cumsum()).cumsum()
# 方法三
# df['Y'] = df.groupby((df['X'] == 0).cumsum()).cumcount()
#first_zero_idx...50.在同一个图中可视化2组数据,共用X轴,但y轴不同
df = pd.DataFrame({"revenue":[57,68,63,71,72,90,80,62,59,51,47,52],