Pandas dataframe：修订间差异
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小无编辑摘要 |
无编辑摘要 |
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[[文件:Pandas DataStructure.png|缩略图|300x300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=== | ===pandas dataframe conversion=== | ||
===dict === | ===dict=== | ||
==== dict -> dataframe==== | ====dict -> dataframe==== | ||
d1 = {"columns":["Apple","Pear"],"data":[[12,0], [8,7], [1, 9]]} | d1 = {"columns":["Apple","Pear"],"data":[[12,0], [8,7], [1, 9]]} | ||
df2 = pd.DataFrame(d1['data']) | df2 = pd.DataFrame(d1['data']) | ||
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Parameters: | 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). | *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. | * 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==== | ====Example==== | ||
... | ... | ||
df2.to_dict('split') | df2.to_dict('split') | ||
2022年12月29日 (四) 14:58的版本
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。