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list pandas python python-2.7 python-3.x

Pad zeros to a Python list

发布于 2020-11-28 22:02:01

I have a dataframe as follows:

df=
year|text|value
2001|text1|10
2001|text2|11
2002|text2|12
2003|text3|56
2005|text8|8
2005|text1|23

Now,I want to make a list of lists from the dataframe as follows:

l1=[[[10,0,0,23],[0,12,0,0],[0,0,56,0],[0,0,0,8]],[text1,text2,text3,text8],[2001,2002,2003,2005]]

I want to add zeros in the list when there is no value for the text in a particular year.

I have tried the following code:

for value in list(df['text'].values):
        df1=df[df['text']==value]
        series_list.append(list(df1['value'].values))
        names_list.append(value)
        year_list.append(list(df1['year'].values))

I did not get the expected output. I initially tried to make 3 separate lists.

Questioner
Sam
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DYZ 2020-11-29 07:14:32

Convert the first two columns to a MultiIndex. Build a rectangular matrix by unstacking one level of the index. Extract the values and arrange them into a list.

matrix = df.set_index(['text', 'year']).unstack(fill_value=0)
matrix.values.tolist()
#[[10, 0, 0, 23], [11, 12, 0, 0], [0, 0, 56, 0], [0, 0, 0, 8]]

Add the index and the columns, if necessary:

matrix.values.tolist() + [matrix.index.tolist()] \
                       + [matrix.columns.levels[1].tolist()]
#[[10, 0, 0, 23], [11, 12, 0, 0], [0, 0, 56, 0], [0, 0, 0, 8],
# ['text1', 'text2', 'text3', 'text8'], [2001, 2002, 2003, 2005]]
Sam 2020-11-28 22:54:31

I also want the order of year to be preserved @DYZ

DYZ 2020-11-28 23:01:53

Updated the answer. The change was obvious.

Sam 2020-11-28 23:08:52

updated the code as follows and worked.[matrix.values.tolist()]+[matrix.index.tolist()]+[matrix.columns.levels[1].tolist()] . It doesn't work with tocolumns because it is multilevel columns @DYZ

DYZ 2020-11-28 23:14:49

Agree, the level selection is necessary.

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