Why is the `df.columns` an empty list while I can see the column names if I print out the dataframe? Python Pandas

Question

import pandas as pd
DATA = pd.read_csv(url)
DATA.head()

I have a large dataset that have dozens of columns. After loading it like above into Colab, I can see the name of each column. But running DATA.columns just return Index([], dtype='object'). What's happening in this?

Now I find it impossible to pick out a few columns without column names. One way is to specify names = [...] when I load it, but I'm reluctant to do that since there're too many columns. So I'm looking for a way to index a column by integers, like in R df[:,[1,2,3]] would simply give me the first three columns of a dataframe. Somehow Pandas seems to focus on column names and makes integer indexing very inconvenient, though.

So what I'm asking is (1) What did I do wrong? Can I obtain those column names as well when I load the dataframe? (2) If not, how can I pick out the [0, 1, 10]th column by a list of integers?

It seems that the problem is in the loading as DATA.shape returns (10000,0). I rerun the loading code a few times, and all of a sudden, things go back normal. Maybe Colab was taking a nap or something?

Use df.iloc[:, [0, 1, 10]] this picks 0, 1, 10th columns. If there no names then df.columns = range(df.shape[1]). — Space Impact
– Space Impact, Commented May 3, 2020 at 19:04
@SandeepKadapa Yeah tried that already. Says IndexError: positional indexers are out-of-bounds — Paw in Data
– Paw in Data, Commented May 3, 2020 at 19:08
@SandeepKadapa Oh now you mentioned it. I print DATA.shape and it returns (10000,0). I guess the problem is in loading, then. — Paw in Data
– Paw in Data, Commented May 3, 2020 at 19:09
@SandeepKadapa This is weird. I rerun the loading code a couple of times and all of a sudden things go back normal. Is Colab that whimsical or what — Paw in Data
– Paw in Data, Commented May 3, 2020 at 19:16

umbreon29 · Accepted Answer · 2020-05-03 19:07:12Z

1

You can perfectly do that using df.loc[:,[1,2,3]] but i would suggest you to use the names because if the columns ever change the order or you insert new columns, the code can break it.

answered May 3, 2020 at 19:07

umbreon29

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Paw in Data Over a year ago

Yeah i'm trying to obtain the column names in the first place as well.

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