注:以下代码是基于python3.5.0编写的
import pandas
food_info = pandas.read_csv(
"food_info.csv")
# ------------------选取数据样本的第一行--------------------
print(food_info.loc[
0])
#------------------选取数据样本的3到6行----------------------
print(food_info.loc[
3:
6])
#------------------head选取数据样本的前几行------------------
print(food_info.head(
2))
# ------------------选取数据样本的2,5,10行,两种方法-----------
# print(food_info.loc[[2,5,10]]) #方法一
two_five_ten = [
2,5,10]
#方法二
print(food_info.loc[two_five_ten])
# ------------------选取数据样本的NDB_No列--------------------
# ndb_col = food_info["NDB_No"] #方法一
col_name =
"NDB_No" #方法二
ndb_col = food_info[col_name]
print(ndb_col)
# ------------------选取数据样本的多列-------------------
# zinc_copper = food_info[["Zinc_(mg)", "Copper_(mg)"]]
columns = [
"Zinc_(mg)", "Copper_(mg)"]
zinc_copper = food_info[columns]
print(zinc_copper)
# ---------------------综合小例子----------------------------
col_names = food_info.columns.tolist()
#把所有的行转化成list
print(col_names)
gram_columns = []
for c
in col_names:
#遍历col_names,找出所有以(g)结尾的位置
if c.endswith(
"(g)"):
gram_columns.append(c)
print(gram_columns)
gram_df = food_info[gram_columns]
#把所有以(g)结尾的列存放到gram_df
print(gram_df.head(
3))
#打印前3行
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