python - Different read_csv index_col = None / 0 / False in pandas -


i used read_csv command following below: 

    in [20]:     dataframe = pd.read_csv('d:/userinterest/output/enfp_0719/bookmark.csv', index_col=none)     dataframe.head()     out[20]:     unnamed: 0  timestamp   url visits     0   0   1.404028e+09    http://m.blog.naver.com/postview.nhn?blogid=mi...   2     1   1   1.404028e+09    http://m.facebook.com/l.php?u=http%3a%2f%2fblo...   1     2   2   1.404028e+09    market://details?id=com.kakao.story 1     3   3   1.404028e+09    https://story-api.kakao.com/upgrade/install 4     4   4   1.403889e+09    http://m.cafe.daum.net/worldcuplove/knj/173424...   1

the result shows column unnamed:0 , simillar when used index_col=false, when used index_col=0, result following below:

dataframe = pd.read_csv('d:/userinterest/output/enfp_0719/bookmark.csv', index_col=0) dataframe.head() out[21]: timestamp   url visits 0   1.404028e+09    http://m.blog.naver.com/postview.nhn?blogid=mi...   2 1   1.404028e+09    http://m.facebook.com/l.php?u=http%3a%2f%2fblo...   1 2   1.404028e+09    market://details?id=com.kakao.story 1 3   1.404028e+09    https://story-api.kakao.com/upgrade/install 4 4   1.403889e+09    http://m.cafe.daum.net/worldcuplove/knj/173424...   1

the result did show column unnamed:0, in here want ask, difference between index_col=none, index_col=0, , index_col=false, have read documentation in this, still did not idea.

update

i think since version 0.16.1 raise error if try pass boolean index_col avoid ambiguity

original

a lot of people confused this, specify ordinal index of column should pass int position in case 0, confuses people when there no index column pass false incorrect should pass none. false evaluate 0 hence result observe.

in [3]:  import io import pandas pd t="""index,a,b 0,hello,pandas""" pd.read_csv(io.stringio(t)) ​ out[3]:    index            b 0      0  hello  pandas

the default value index_col=none shown above.

if set index_col=0 we're explicitly stating treat first column index:

in [4]:  pd.read_csv(io.stringio(t), index_col=0) out[4]:                  b index                0      hello  pandas

if pass index_col=false same result above due false evaluating 0:

in [5]:  pd.read_csv(io.stringio(t), index_col=false) out[5]:    index            b 0      0  hello  pandas

if state index_col=none same behaviour when didn't pass param:

in [6]:  pd.read_csv(io.stringio(t), index_col=none) out[6]:    index            b 0      0  hello  pandas

edit

for case have blank index column have:

in [7]:  import io import pandas pd t=""",a,b 0,hello,pandas""" pd.read_csv(io.stringio(t)) ​ out[7]:    unnamed: 0            b 0           0  hello  pandas in [8]:  pd.read_csv(io.stringio(t), index_col=0) out[8]:              b 0  hello  pandas in [9]:  pd.read_csv(io.stringio(t), index_col=false) out[9]:    unnamed: 0            b 0           0  hello  pandas in [10]:  pd.read_csv(io.stringio(t), index_col=none) out[10]:    unnamed: 0            b 0           0  hello  pandas

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