0

This isn't exactly a question about how to find all unique entries in a column of a dataframe, since I know how I'd do that:

import pandas as pd

df = pd.read_csv('test.txt',delim_whitespace=True)

for key in list(df.keys()):
    uni = set(df[key])

What this is really about, is how to do it with pandas' own methods/functions dynamically and this strange syntax that I can't understand why anyone would use it:

In [101]: list(df.keys())
Out[101]: ['id_cliente', 'id_ordine', 'data_ordine', 'id_medium']

With these keys, you can find their unique column values with the following syntax:

In [102]: df.id_cliente.unique()
Out[102]: array(['madinside', 'lisbeth19'], dtype=object)

I can't use this method dynamically like in my iteration above, can I? I can only use it, if I find out the keys first and manually type in the df.NAME.unique() statement, right?

Why is this a thing? Is this method exclusively intended for interactive use from the python console? Is there a native pandas.DataFrame method for determining unique values dynamically?

J.Doe
  • 224
  • 1
  • 4
  • 19

2 Answers2

1

Does this work for your df? 

unique_stuff = [{col: set(df[col].unique())} for col in df.columns]

edit: actually I don't think you even need a set here. I've removed it below:

unique_stuff  = [{col: df[col].unique().tolist()} for col in df.columns]
SCool
  • 3,104
  • 4
  • 21
  • 49
  • Yeah I could do that, it's just that I found it weird that you can access a column of a dataframe by using it's column name *string* as a *code fragment*. Doesn't this mean, that when a DataFrame instance is created, the column names are used to create static variables, where the name of the static variables is also the name of the column? Am I the only one who finds this weird? https://stackoverflow.com/questions/68645/are-static-class-variables-possible-in-python – J.Doe Sep 20 '19 at 16:10
1

You can do it dynamically 

df.T.apply(pd.Series.unique,1)
BENY
  • 317,841
  • 20
  • 164
  • 234
  • Thanks. But could you maybe tell me, if the syntax is actually weird or if I'm just weird? Look at my other comment if you want to know what I mean? – J.Doe Sep 20 '19 at 19:47