pandas 如何创建具有重复字符串值的数据框列？
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How to create a dataframe column with repeated string value?
提问by Katie R
I'm reading in data from a bunch of files and storing it in a data frame. I want a column of the data frame to indicate which file the data came from. How do I create a column that has the same string repeated over and over without typing it out manually?
我正在从一堆文件中读取数据并将其存储在数据框中。我想要一列数据框来指示数据来自哪个文件。如何创建一个重复重复相同字符串的列，而无需手动输入？
Each file I'm reading in has ~100 data points (but not the same number each time). As I read each one in, I will concat to the dataframe along axis=0. It should look like this.
我正在读入的每个文件都有大约 100 个数据点（但每次都不是相同的数字）。当我阅读每一个时，我将沿轴 = 0 连接到数据框。它应该是这样的。
import numpy as np
import pandas as pd
numbers = np.random.randn(5) # this data could be of any length, ~100
labels = np.array(['file01','file01','file01','file01','file01'])
tf = pd.DataFrame()
tf['labels'] = labels
tf['numbers'] = numbers
In [8]: tf
Out[8]:
labels numbers
0 file01 -0.176737
1 file01 -1.243871
2 file01 0.154886
3 file01 0.236653
4 file01 -0.195053
(Yes, I know I could make 'file01' a column header and append each one along axis=1, but there are reasons I don't want to do it that way.)
（是的，我知道我可以将 'file01' 作为列标题并沿轴 = 1 附加每个标题，但有一些原因我不想这样做。）
采纳答案by Flavian Hautbois
There you go, your code is fixed! You can actually put a single value in the dict used in the DataFrame constructor :).
好了，您的代码已修复！您实际上可以在 DataFrame 构造函数中使用的 dict 中放置一个值:)。
import numpy as np
import pandas as pd
filename = 'file01'
numbers = np.random.randn(5) # this data could be of any length, ~100
tf = pd.DataFrame({'labels': filename , 'numbers': numbers})
In [8]: tf
Out[8]:
labels numbers
0 file01 -0.176737
1 file01 -1.243871
2 file01 0.154886
3 file01 0.236653
4 file01 -0.195053
