查看“Pandas dataframe”的源代码

[[文件:Pandas_DataStructure.png|右|无框|600x600像素]]
　  　 DataFrame 是一个表格型的数据结构，它含有一组有序的列，每列可以是不同的值类型（数值、字符串、布尔型值）。DataFrame 既有行索引也有列索引，它可以被看做由 Series 组成的字典（共同用一个索引）。

===pandas dataframe conversion===
===dict===
====dict -> dataframe====
 d1 = {"columns":["Apple","Pear"],"data":[[12,0], [8,7], [1, 9]]}
 df2 = pd.DataFrame(d1['data'])
    Apple  Pear
 0     12     0
 1      8     7
 2      1     9
 
 df2.columns=d1['columns']
 Index(['Apple', 'Pear'], dtype='object')
====dataframe -> dict====
Syntax: DataFrame.to_dict(orient=’dict’, into=)

Parameters:
*orient: String value, (‘dict’, ‘list’, ‘series’, ‘split’, ‘records’, ‘index’) Defines which dtype to convert Columns(series into). For example, ‘list’ would return a dictionary of lists with Key=Column name and Value=List (Converted series).
*into: class, can pass an actual class or instance. For example in case of defaultdict instance of class can be passed. Default value of this parameter is dict.
====Example====
 ...
 df2.to_dict('split')
 {'index': [0, 1, 2], 'columns': ['Apple', 'Pear'], 'data': [[12, 0], [8, 7], [1, 9]]}
 
 df2.to_dict('records')
 [{'Apple': 12, 'Pear': 0}, {'Apple': 8, 'Pear': 7}, {'Apple': 1, 'Pear': 9}]
===list===
====list -> dataframe====
　　See also: dict -> dataframe
====dataframe -> list====
 a1 = df1.values    # values方法将dataframe转为numpy.ndarray
 l1 = a1.tolist()
 l1[0]              # get frist value
 usys.utime(l1[0][7].value/10**9) * P.S. 日期型的字段转换后格式：Timestamp('2017-04-13 13:48:32')，pandas._libs.tslibs.timestamps.Timestamp. 可以使用 usys.utime(l1[0][7].value/10**9) 转换。
[[分类:Develop]]
[[分类:Python]]
[[分类:Pandas]]