pandas中把读取到的string值转换成object类型

pd.read_csv dataFrame .head .tail() .columns .shape .dtypes

.loc[col_name] 取列 

col_names = food_info.columns.tolist()
print(col_names)
gram_columns = []

for c in col_names:
    if c.endswith("(g)"):
        gram_columns.append(c)
gram_df = food_info[gram_columns]
print(gram_df.head(3))

dataFrame Series

归一化操作：除以最大值.max()

food_info.sort_values("xzc",inplace=True) 是新列

.pivot_table()相当于数据透视表

passenger_survival = titanic_survival.pivot_table(index="pclass",values="survived",aggfunc=np.mean)
print(passenger_survival)
#index以谁为基准 values算什么

dropna()  fillna() apply() 完成转换

def generate_age_label():

if pd.isnull(age）

Series

ndarray<series<dataFrame