Pandas 基础学习
2018-06-18 01:36:58来源：未知 阅读 ()
加载数据
Fun：pandas.read_csv
>>> import pandas
>>> food_info = pandas.read_csv("food_info.csv")
>>> print(food_info.dtypes)
NDB_No int64
Shrt_Desc object
Water_(g) float64
Energ_Kcal int64
Protein_(g) float64
Lipid_Tot_(g) float64
Ash_(g) float64
Carbohydrt_(g) float64
Fiber_TD_(g) float64
Sugar_Tot_(g) float64
Calcium_(mg) float64
Iron_(mg) float64
Magnesium_(mg) float64
Phosphorus_(mg) float64
Potassium_(mg) float64
Sodium_(mg) float64
Zinc_(mg) float64
Copper_(mg) float64
Manganese_(mg) float64
Selenium_(mcg) float64
Vit_C_(mg) float64
Thiamin_(mg) float64
Riboflavin_(mg) float64
Niacin_(mg) float64
Vit_B6_(mg) float64
Vit_B12_(mcg) float64
Vit_A_IU float64
Vit_A_RAE float64
Vit_E_(mg) float64
Vit_D_mcg float64
Vit_D_IU float64
Vit_K_(mcg) float64
FA_Sat_(g) float64
FA_Mono_(g) float64
FA_Poly_(g) float64
Cholestrl_(mg) float64
dtype: object
>>> print(type(food_info))
<class 'pandas.core.frame.DataFrame'>
取数据的头和尾
头：head
food_info.head(1)
尾：tail
food_info.tail(1)
shape
>>> food_info.shape
(8618, 36)
取数据
指定行数据
>>> print(food_info.loc[0])
NDB_No 1001
Shrt_Desc BUTTER WITH SALT
Water_(g) 15.87
Energ_Kcal 717
Protein_(g) 0.85
Lipid_Tot_(g) 81.11
Ash_(g) 2.11
Carbohydrt_(g) 0.06
Fiber_TD_(g) 0
Sugar_Tot_(g) 0.06
Calcium_(mg) 24
Iron_(mg) 0.02
Magnesium_(mg) 2
Phosphorus_(mg) 24
Potassium_(mg) 24
Sodium_(mg) 643
Zinc_(mg) 0.09
Copper_(mg) 0
Manganese_(mg) 0
Selenium_(mcg) 1
Vit_C_(mg) 0
Thiamin_(mg) 0.005
Riboflavin_(mg) 0.034
Niacin_(mg) 0.042
Vit_B6_(mg) 0.003
Vit_B12_(mcg) 0.17
Vit_A_IU 2499
Vit_A_RAE 684
Vit_E_(mg) 2.32
Vit_D_mcg 1.5
Vit_D_IU 60
Vit_K_(mcg) 7
FA_Sat_(g) 51.368
FA_Mono_(g) 21.021
FA_Poly_(g) 3.043
Cholestrl_(mg) 215
Name: 0, dtype: object
取范围数据
>>> print(food_info.loc[1:2])
NDB_No Shrt_Desc Water_(g) Energ_Kcal Protein_(g) \
1 1002 BUTTER WHIPPED WITH SALT 15.87 717 0.85
2 1003 BUTTER OIL ANHYDROUS 0.24 876 0.28
Lipid_Tot_(g) Ash_(g) Carbohydrt_(g) Fiber_TD_(g) Sugar_Tot_(g) \
1 81.11 2.11 0.06 0.0 0.06
2 99.48 0.00 0.00 0.0 0.00
... Vit_A_IU Vit_A_RAE Vit_E_(mg) Vit_D_mcg Vit_D_IU \
1 ... 2499.0 684.0 2.32 1.5 60.0
2 ... 3069.0 840.0 2.80 1.8 73.0
Vit_K_(mcg) FA_Sat_(g) FA_Mono_(g) FA_Poly_(g) Cholestrl_(mg)
1 7.0 50.489 23.426 3.012 219.0
2 8.6 61.924 28.732 3.694 256.0
取列数据
>>> print(food_info["NDB_No"])
0 1001
1 1002
2 1003
3 1004
4 1005
5 1006
6 1007
7 1008
8 1009
9 1010
10 1011
11 1012
12 1013
13 1014
14 1015
15 1016
16 1017
17 1018
18 1019
19 1020
20 1021
21 1022
22 1023
23 1024
24 1025
25 1026
26 1027
27 1028
28 1029
29 1030
...
8588 43544
8589 43546
8590 43550
8591 43566
8592 43570
8593 43572
8594 43585
8595 43589
8596 43595
8597 43597
8598 43598
8599 44005
8600 44018
8601 44048
8602 44055
8603 44061
8604 44074
8605 44110
8606 44158
8607 44203
8608 44258
8609 44259
8610 44260
8611 48052
8612 80200
8613 83110
8614 90240
8615 90480
8616 90560
8617 93600
Name: NDB_No, Length: 8618, dtype: int64
取多个列的数据
>>> print(food_info[["NDB_No","Shrt_Desc"]])
NDB_No Shrt_Desc
0 1001 BUTTER WITH SALT
1 1002 BUTTER WHIPPED WITH SALT
2 1003 BUTTER OIL ANHYDROUS
3 1004 CHEESE BLUE
4 1005 CHEESE BRICK
5 1006 CHEESE BRIE
6 1007 CHEESE CAMEMBERT
7 1008 CHEESE CARAWAY
8 1009 CHEESE CHEDDAR
9 1010 CHEESE CHESHIRE
10 1011 CHEESE COLBY
11 1012 CHEESE COTTAGE CRMD LRG OR SML CURD
12 1013 CHEESE COTTAGE CRMD W/FRUIT
13 1014 CHEESE COTTAGE NONFAT UNCRMD DRY LRG OR SML CURD
14 1015 CHEESE COTTAGE LOWFAT 2% MILKFAT
15 1016 CHEESE COTTAGE LOWFAT 1% MILKFAT
16 1017 CHEESE CREAM
17 1018 CHEESE EDAM
18 1019 CHEESE FETA
19 1020 CHEESE FONTINA
20 1021 CHEESE GJETOST
21 1022 CHEESE GOUDA
22 1023 CHEESE GRUYERE
23 1024 CHEESE LIMBURGER
24 1025 CHEESE MONTEREY
25 1026 CHEESE MOZZARELLA WHL MILK
26 1027 CHEESE MOZZARELLA WHL MILK LO MOIST
27 1028 CHEESE MOZZARELLA PART SKIM MILK
28 1029 CHEESE MOZZARELLA LO MOIST PART-SKIM
29 1030 CHEESE MUENSTER
... ... ...
8588 43544 BABYFOOD CRL RICE W/ PEARS & APPL DRY INST
8589 43546 BABYFOOD BANANA NO TAPIOCA STR
8590 43550 BABYFOOD BANANA APPL DSSRT STR
8591 43566 SNACKS TORTILLA CHIPS LT (BAKED W/ LESS OIL)
8592 43570 CEREALS RTE POST HONEY BUNCHES OF OATS HONEY RSTD
8593 43572 POPCORN MICROWAVE LOFAT&NA
8594 43585 BABYFOOD FRUIT SUPREME DSSRT
8595 43589 CHEESE SWISS LOW FAT
8596 43595 BREAKFAST BAR CORN FLAKE CRUST W/FRUIT
8597 43597 CHEESE MOZZARELLA LO NA
8598 43598 MAYONNAISE DRSNG NO CHOL
8599 44005 OIL CORN PEANUT AND OLIVE
8600 44018 SWEETENERS TABLETOP FRUCTOSE LIQ
8601 44048 CHEESE FOOD IMITATION
8602 44055 CELERY FLAKES DRIED
8603 44061 PUDDINGS CHOC FLAVOR LO CAL INST DRY MIX
8604 44074 BABYFOOD GRAPE JUC NO SUGAR CND
8605 44110 JELLIES RED SUGAR HOME PRESERVED
8606 44158 PIE FILLINGS BLUEBERRY CND
8607 44203 COCKTAIL MIX NON-ALCOHOLIC CONCD FRZ
8608 44258 PUDDINGS CHOC FLAVOR LO CAL REG DRY MIX
8609 44259 PUDDINGS ALL FLAVORS XCPT CHOC LO CAL REG DRY MIX
8610 44260 PUDDINGS ALL FLAVORS XCPT CHOC LO CAL INST DRY...
8611 48052 VITAL WHEAT GLUTEN
8612 80200 FROG LEGS RAW
8613 83110 MACKEREL SALTED
8614 90240 SCALLOP (BAY&SEA) CKD STMD
8615 90480 SYRUP CANE
8616 90560 SNAIL RAW
8617 93600 TURTLE GREEN RAW
[8618 rows x 2 columns]
取所有的列名
>>> food_info.columns.tolist()
['NDB_No', 'Shrt_Desc', 'Water_(g)', 'Energ_Kcal', 'Protein_(g)', 'Lipid_Tot_(g)', 'Ash_(g)', 'Carbohydrt_(g)', 'Fiber_TD_(g)', 'Sugar_Tot_(g)', 'Calcium_(mg)', 'Iron_(mg)', 'Magnesium_(mg)', 'Phosphorus_(mg)', 'Potassium_(mg)', 'Sodium_(mg)', 'Zinc_(mg)', 'Copper_(mg)', 'Manganese_(mg)', 'Selenium_(mcg)', 'Vit_C_(mg)', 'Thiamin_(mg)', 'Riboflavin_(mg)', 'Niacin_(mg)', 'Vit_B6_(mg)', 'Vit_B12_(mcg)', 'Vit_A_IU', 'Vit_A_RAE', 'Vit_E_(mg)', 'Vit_D_mcg', 'Vit_D_IU', 'Vit_K_(mcg)', 'FA_Sat_(g)', 'FA_Mono_(g)', 'FA_Poly_(g)', 'Cholestrl_(mg)']
排序
升序
inplace = True代表在当前对象内直接排序，如果要返回一个新的对象 set False
food_info.sort_values("Water_(g)",inplace = True)
>>> food_info["Water_(g)"]
>>> 760 0.00
8599 0.00
654 0.00
631 0.00
630 0.00
629 0.00
611 0.00
610 0.00
655 0.00
673 0.00
663 0.00
671 0.00
670 0.00
669 0.00
633 0.00
668 0.00
700 0.00
665 0.00
664 0.00
662 0.00
656 0.00
661 0.00
660 0.00
659 0.00
658 0.00
657 0.00
699 0.00
737 0.00
8122 0.00
667 0.00
...
4270 99.80
4411 99.85
4408 99.89
4357 99.90
4239 99.90
4356 99.90
4369 99.90
4347 99.90
4205 99.90
4203 99.93
4204 99.95
4208 99.95
4213 99.95
4374 99.96
4407 99.97
4379 99.97
4373 99.97
4404 99.98
4372 99.98
4377 100.00
4378 100.00
4348 100.00
4209 100.00
4376 100.00
6150 NaN
6067 NaN
6113 NaN
1983 NaN
7776 NaN
6095 NaN
降序
>>> food_info.sort_values("Water_(g)",inplace = True , ascending = False)
>>> food_info["Water_(g)"]
4376 100.00
4209 100.00
4348 100.00
4378 100.00
4377 100.00
4372 99.98
4404 99.98
4407 99.97
4379 99.97
4373 99.97
4374 99.96
4213 99.95
4208 99.95
4204 99.95
4203 99.93
4356 99.90
4357 99.90
4239 99.90
4205 99.90
4369 99.90
4347 99.90
4408 99.89
4411 99.85
4270 99.80
4252 99.80
4392 99.80
4260 99.80
4409 99.79
4255 99.74
4397 99.70
...
739 0.00
790 0.00
638 0.00
689 0.00
688 0.00
687 0.00
686 0.00
685 0.00
666 0.00
632 0.00
653 0.00
639 0.00
696 0.00
8455 0.00
791 0.00
675 0.00
8180 0.00
704 0.00
705 0.00
706 0.00
707 0.00
738 0.00
6417 0.00
760 0.00
6150 NaN
6067 NaN
6113 NaN
1983 NaN
7776 NaN
6095 NaN
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