how to create the subcolumns in the dataframe and add the data using pandas in python

Question

Actually, I am facing the problem to add the data in the subcolumn in the specific format. I have created the "Polypoints" as the main column and I want

df["Polypoints"] = [{"__type":"Polygon","coordinates":Row_list}]

where Row_list is the column of dataframe which contains the data in the below format

df["Row_list"] = [[x1,y1],[x2,y2],[x3,y3]
                 [x1,y1],[x2,y2],[x3,y3]
                 [x1,y1],[x2,y2],[x3,y3]]

I want to convert the dataframe into json in the format "Polypoints" :{"__type":"Polygon" ,"coordinates":Row_list}

I have to add one more column "Polypoints" in the Dataframe as specified above and add the data of Row_list column in the "coordinates" subcolumn. — A.D, Sep 26 '19 at 04:42
Try the `json` or `jsonpickle` packages. E.g. `json.dumps(df)`. — André Müller, Sep 26 '19 at 04:50
Base on the question https://stackoverflow.com/questions/58091927/how-to-concatenate-pairs-of-row-elements-into-a-new-column-in-a-pandas-dataframe I have issue related to the above answer. Please check the link and suggest for the issue — A.D, Sep 26 '19 at 04:58
Did you try `json` like proposed in comment above? It sounds to me like a good option... — Itamar Mushkin, Sep 26 '19 at 05:53
before json I have to create one column in the dataframe "Polypoint" specified in the above format — A.D, Sep 26 '19 at 06:01
The DataFrame Column "Polypoints" once created in the specific format then it is easier to directly get the json file. — A.D, Sep 26 '19 at 06:05
try `df['Polypoints'] = df.apply(lambda row: {"__type":"Polygon", "coordinates":row['Row_list']} ,axis=1)` — Itamar Mushkin, Sep 26 '19 at 06:06
Also suggest for the question posted at https://stackoverflow.com/questions/58112213/how-to-read-the-sublist-from-the-main-list-and-add-the-sublist-in-the-another-da — A.D, Sep 26 '19 at 09:50

score 0 · Answer 1 · answered Sep 06 '22 at 15:05

There are various ways to do that.

One can create a function create_polygon that takes as input the dataframe (df), and the column name (columname). That would look like the following

def create_polygon(df, columnname):
    return {"__type":"Polygon", "coordinates":df[columnname]}

Considering that the column name will be Row_list, the following will already be enough

def create_polygon(df):
    return {"__type":"Polygon", "coordinates":df['Row_list']}

Then with pandas.DataFrame.apply one can apply it to the column Polypoints as follows

df['Polypoints'] = df.apply(create_polygon, axis=1)

As Itamar Mushkin mentions, one can also do it with a Lambda function as follows

df['Polypoints'] = df.apply(lambda row: {"__type":"Polygon", "coordinates":row['Row_list']} ,axis=1)

how to create the subcolumns in the dataframe and add the data using pandas in python

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