如何将 Pandas 列转换为数组并转置它？
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How to turn a Pandas column into array and transpose it?
提问by Stanleyrr
I have a Pandas dataframe called 'training_set' that resembles the screenshot below:
我有一个名为“training_set”的 Pandas 数据框，类似于下面的屏幕截图：
I try to turn the 'label' column into array and transpose it. I tried doing Y_train=np.asarray(training_set['label'])but what I got is a horizontal array that resembles the screenshot below, which is not what I want.
我尝试将“标签”列转换为数组并将其转置。我尝试过，Y_train=np.asarray(training_set['label'])但我得到的是一个类似于下面屏幕截图的水平数组，这不是我想要的。
I want the array to display vertically just like the screenshot below (The screenshot has 2 variables per row. My desired output should only contain 1 variable, the 'label', per row.)
我希望数组像下面的屏幕截图一样垂直显示（屏幕截图每行有 2 个变量。我想要的输出应该只包含 1 个变量，即“标签”，每行。）
Any suggestion or help would be greatly appreciated!
任何建议或帮助将不胜感激！
回答by cs95
pandas >= 0.24
Pandas >= 0.24
Use DataFrame.to_numpy(), the new Right Way to extract a numpy array:
使用DataFrame.to_numpy()新的正确方法来提取 numpy 数组：
training_set[['label']].to_numpy()
pandas < 0.24
Pandas < 0.24
Slice out your column as a single columned DataFrame(using [[...]]), not as a Series:
将您的列切成单列DataFrame（使用[[...]]），而不是作为Series：
Y_train = np.asarray(training_set[['label']])
Or,
或者，
Y_train = training_set[['label']].values
回答by sacuL
Another way would be to reshape your array to shape (-1,1), which means "infer number of rows, force to 1 column":
另一种方法是将数组重塑为 shape (-1,1)，这意味着“推断行数，强制为 1 列”：
Y_train = np.array(training_set['label']).reshape(-1,1)
回答by jpp
One way:
单程：
Y_train = training_set['label'].values[:, None]
