Python 将数据帧转换为列表
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Convert dataFrame to list
提问by Pau Folch Codera
I have a pandas dataframe that I convert to numpy array as follows:
我有一个 Pandas 数据框，我将其转换为 numpy 数组，如下所示：
df.values
which gives the following output:
这给出了以下输出：
array([[2],
[0],
[1],
...,
[0],
[1],
[0]], dtype=int64)
However I want to obtain the list as follows:
但是我想获得如下列表：
[0, 2, 3]
Any idea how to do this?
知道如何做到这一点吗？
采纳答案by jezrael
Maybe you can use ilocor locfor selecting column and then tolist:
print df
a
0 2
1 0
2 1
3 0
4 1
5 0
print df.values
[[2]
[0]
[1]
[0]
[1]
[0]]
print df.iloc[:, 0].tolist()
[2, 0, 1, 0, 1, 0]
Or maybe:
或者可能：
print df.values.tolist()
[[2L], [0L], [1L], [0L], [1L], [0L]]
print df.iloc[:, 0].values.tolist()
[2L, 0L, 1L, 0L, 1L, 0L]
print df.loc[:, 'a'].tolist()
[2, 0, 1, 0, 1, 0]
print df['a'].tolist()
[2, 0, 1, 0, 1, 0]
But maybe you need flatten:
但也许你需要flatten：
print df.values.flatten()
[2 0 1 0 1 0]
print df.iloc[:, 0].values.flatten()
[2 0 1 0 1 0]
回答by OkezieE
Looks like you have a dataframe with one column and several rows. Remember that this is a two dimensional array, you have to slice the first column then list the values within that column.
看起来您有一个包含一列多行的数据框。请记住，这是一个二维数组，您必须对第一列进行切片，然后列出该列中的值。
This should do it:
这应该这样做：
df[0].values.tolist()
df[0]- This selects all values in the first column. For the second column you'd use df[1]third df[2]and so on.
df[0]- 这将选择第一列中的所有值。对于第二列，您将使用df[1]第三列df[2]，依此类推。
You can tell the shape of your dataframe by running df.shape. This will tell you how many rows and columns exist in your dataframe e.g. (9,1)which means 9 rows and 1 column
您可以通过运行来判断数据框的形状df.shape。这将告诉您数据框中存在多少行和列，例如(9,1)，这意味着 9 行和 1 列
