是否将CSV文件的注释行保留在Pandas中？

Question

我刚刚开始深入研究熊猫的世界，我发现的第一个奇怪的CSV文件是一个开头有两行注释（不同列宽）的文件

sometext, sometext2
moretext, moretext1, moretext2
*header*
actual data ---
---------------

我知道如何使用skiprows或header=跳过这些行，但是，在使用read_csv时如何保留这些注释呢？有时注释作为文件元信息是必要的，我不想把它们扔掉

Answer 1

您可以先读取元数据，然后使用read_csv：

with open('f.csv') as file:
    #read first 2 rows to metadata
    header = [file.readline() for x in range(2)]
    meta = [value.strip().split(',') for value in header]
    print (meta)
    [['sometext', ' sometext2'], ['moretext', ' moretext1', ' moretext2']]

    df = pd.read_csv(file)
    print (df)

          *header*
    0  actual data

Answer 2

Pandas设计用于读取结构化数据

对于非结构化数据，只需使用内置的^{}：

with open('file.csv') as f:
    reader = csv.reader(f)
    row1 = next(reader)  # gets the first line
    row2 = next(reader)  # gets the second line

您可以像这样将字符串附加到数据帧：

df.comments = 'My Comments'

But note：

Note, however, that while you can attach attributes to a DataFrame, operations performed on the DataFrame (such as groupby, pivot, join or loc to name just a few) may return a new DataFrame without the metadata attached. Pandas does not yet have a robust method of propagating metadata attached to DataFrames.