Pandas tuple with value and dictionary into dataframe

Question

Currently, I have data in the following form:

ie.

[ ('ab', {'a' : [apple1], 'b': [ball1]}), ('cd', {'a' : [apple2], 'b':   [ball2]})]  

List[Tuple[Any, dict{'key':List}]]

The goal is to create a pandas data frame in the following form:

start   a             b
ab    apple1         ball1
cd    apple2         ball2

I have tried to it the following way:

df = pd.DataFrame(columns=['start', 'a', 'b'])
for start, details in mylist:
    df = df.append({'start' : start}, ignore_index= True)
    df = df.append({'a' : details['a']} , ignore_index= True)
    df = df.append({'b': details['b']}, ignore_index=True)

I'm trying to figure out an optimized way to do this.

Answer 1

pd.DataFrame.from_dict

Pandas works well with a dictionary or a list of dictionaries. You have something in between. In this case, converting to a dictionary is trivial:

L = [('ab', {'a' : ['apple1'], 'b': ['ball1']}),
     ('cd', {'a' : ['apple2'], 'b': ['ball2']})]

res = pd.DataFrame.from_dict(dict(L), orient='index')
res = res.apply(lambda x: x.str[0])

print(res)

         a      b
ab  apple1  ball1
cd  apple2  ball2

Answer 2

Like this:

form = [ ('ab', {'a' : ['apple1'], 'b': ['ball1']}), ('cd', {'a' : ['apple2'], 'b':   ['ball2']})]

# separate 'start' from rest of data - inverse zip
start, data = zip(*form)

# create dataframe
df = pd.DataFrame(list(data))

# remove data from lists in each cell
df = df.applymap(lambda l: l[0])

df.insert(loc=0, column='start', value=start)

print(df)
     start     a      b
0    ab   apple1  ball1
1    cd   apple2  ball2

or, if you want start to be the index of the dataframe:

# separate 'start' from rest of data - inverse zip
index, data = zip(*form)

# create dataframe
df = pd.DataFrame(list(data), index=index)
df.index.name = 'start' 

# remove data from lists in each cell
df = df.applymap(lambda l: l[0])

print(df)
start     a      b
ab   apple1  ball1
cd   apple2  ball2