pandas 如何将数据框列表保存到 csv
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How to save a list of dataframes to csv
提问by Sergey Gulbin
I have a list of data frames which I reshuffle and then I want to save the output as a csv. To do this I'm trying to append this list to an empty data frame:
我有一个我重新洗牌的数据帧列表，然后我想将输出保存为 csv。为此，我尝试将此列表附加到空数据框中：
l1=[year1, year2,..., year30]
shuffle (l1)
columns=['year', 'day', 'tmin', 'tmax', 'pcp']
index=np.arange(10957)
df2=pd.DataFrame(columns=columns, index=index)
l1.append(df2)
This result in an empty data frames with a bunch of Nans. I don't necessarily need to append my reshuffled list to a dataframe, I just need to save it as a csv, and this is the only way I find yet.
这导致带有一堆 Nans 的空数据帧。我不一定需要将改组后的列表附加到数据帧中，我只需要将其另存为 csv，这是我找到的唯一方法。
回答by jezrael
回答by computerist
An alternative to the chosen answer is to open the CSV and append one dataframe at a time inside a loop. This can be order of magnitude faster depending on the size of data.
所选答案的替代方法是打开 CSV 并在循环内一次附加一个数据帧。根据数据的大小，这可以快几个数量级。
f = open(filename, 'a')
for df in l1:
df.to_csv(f)
f.close()
