python - Create dataframe from specific column -


i trying create dataframe in pandas ab column in csv file. (ab 27th column).

i using line:

df = pd.read_csv(filename, error_bad_lines = false, usecols = [27])

... resulting in error:

valueerror: usecols not match names.

i'm new pandas, point out i'm doing wrong me?

here small demo:

csv file (without header, i.e. there no column names):

1,2,3,4,5,6,7,8,9,10 11,12,13,14,15,16,17,18,19,20

we going read 8-th column:

in [1]: fn = r'd:\temp\.data\1.csv'  in [2]: df = pd.read_csv(fn, header=none, usecols=[7], names=['col8'])  in [3]: df out[3]:    col8 0     8 1    18

ps pay attention @ header=none, usecols=[7], names=['col8']

if don't use header=none , names parameters, first row used header:

in [6]: df = pd.read_csv(fn, usecols=[7])  in [7]: df out[7]:     8 0  18  in [8]: df.columns out[8]: index(['8'], dtype='object')

and if want read last 10-th column:

in [9]: df = pd.read_csv(fn, usecols=[10]) ... skipped ... valueerror: usecols not match names.

because pandas counts columns starting 0, have way:

in [12]: df = pd.read_csv(fn, usecols=[9], names=['col10'])  in [13]: df out[13]:    col10 0     10 1     20

-

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