pandas Python：在csv中导出矩阵

Python: Export a matrix in csv

提问by Plug4

I have a 2D matrix with 13 rows and 13 columns (with headers except for the first column) named correlin Python. This correlmatrix was generated from a DataFrameand I wish to populate a matrix correlationwith multiple correl. For example:

我有一个 2D 矩阵，有 13 行和 13 列（除了第一列之外还有标题）correl，用 Python命名。这个correl矩阵是从 a 生成的DataFrame，我希望correlation用多个correl. 例如：

correlation=[]
correl=df.corr()
correlation=correlation.append(correl) #correlation is not a DataFrame

The reason why I use the correlation=[]it is because I wish to populate the correlationwith multiple correlation tables. That is why I use the appendsince this is in a loop.

我使用correlation=[]它的原因是因为我希望correlation用多个相关表填充它。这就是我使用 的原因，append因为这是在循环中。

Now I wish to export this correlation matrix in a csv file. I do:

现在我希望将此相关矩阵导出到 csv 文件中。我愿意：

with open("C:\destinationfolder\file.csv", "wb") as f:
    writer = csv.writer(f)
    writer.writerows(correlation)

I get this error:

我收到此错误：

raise KeyError('no item named %s' % com.pprint_thing(item)) KeyError: u'no item named 0'

raise KeyError('no item named %s' % com.pprint_thing(item)) KeyError: u'no item named 0'

Why? My guess is that I don't have a header for the first column... is there an easier way to export my correlation table to csv?

为什么？我的猜测是我没有第一列的标题......有没有更简单的方法将我的相关表导出到 csv？

回答by Andy Hayden

It looks like correlationis a DataFrame too, so you can simply use to_csv:

它看起来correlation也是一个 DataFrame，所以你可以简单地使用to_csv：

correlation.to_csv("C:\destinationfolder\file.csv")

Update to answer if you have a list of DataFrames:

如果您有数据帧列表，请更新回答：

If you have a list of DataFrames which you want to make into a csv, you have two options:

如果您有要制作成 csv 的 DataFrame 列表，您有两个选择：

1. concat the list into one larger frame, and use to_csv:

   pd.concat(list_of_dataframes).to_csv(...)
   

2. iterate over each DataFrame and use to_csvwith append (mode='a'). Something like:

   list_of_dataframes[0].to_csv(...)  # write first, using headers..  assumes list isn't empty!
   for df in list_of_dataframes[1:]:
       df.to_csv(..., header=False, mode='a')
   

   see https://stackoverflow.com/a/17531025/1240268.

1. 将列表连接到一个更大的框架中，并使用to_csv：

   pd.concat(list_of_dataframes).to_csv(...)
   

2. 迭代每个 DataFrame 并to_csv与 append ( mode='a') 一起使用。就像是：

   list_of_dataframes[0].to_csv(...)  # write first, using headers..  assumes list isn't empty!
   for df in list_of_dataframes[1:]:
       df.to_csv(..., header=False, mode='a')
   

   见https://stackoverflow.com/a/17531025/1240268。