"Python：使用多个标题行写入 CSV"

Question

Context<\/h3>

I am looking to export a dictionary which contains a list of dictionaries as the value of each key:value<\/em> pair:

Answer 1

so far I have reached here:

d = {'key_1':
    [{'key_a': 'foo_1', 'key_b': 'bar_1'}, 
     {'key_a': 'foo_2', 'key_b': 'bar_2'}], 
    'key_2':
    [{'key_c': 'foo_1', 'key_d': 'bar_1'}, 
     {'key_c': 'foo_2', 'key_d': 'bar_2'}]}
df = pd.DataFrame(d)
df1 = []
for col in df.columns:
    data = df[col].apply(pd.Series)
    data = df1.append(data)
df1 = pd.concat(df1,axis=1)
print(df1)

which gives you:

  key_a   key_b    key_c     key_d
0 foo_1   bar_1    foo_1     bar_1 
1 foo_2   bar_2    foo_2     bar_2 

Rest you have to map the respective keys in regards to your original column names and tat can be placed in df1.loc[-1] as an identifier. I will update once I get something.

Answer 2

Here your "List Index" is a merged cell which you can't achieve in a CSV file because it doesn't contain formatting. You can either:

a) Write it to a xlsx file ( XlsxWriter is a great library for this)

b) Keep it was a CSV but with an unmerged cell as anky_91 suggests

Answer 3

here's a solution for creating fieldnames<\/code> for DictWriter()<\/code> for a dictionary that contains dictionaries and also lists of dictionaries.

#!/usr/bin/env python3
import csv
import pprint as pp

myDict = {'key_1':
        [{'key_a': 'foo_1', 'key_b': 'bar_1'}, 
         {'key_a': 'foo_2', 'key_b': 'bar_2'}], 
        'key_2':
        [{'key_c': 'foo_1', 'key_d': 'bar_1'}, 
         {'key_c': 'foo_2', 'key_d': 'bar_2'}] }

def generateFieldnames(myDict):
    # create unique fieldnames from a dictionary containing dictionaries
    newDict={}
    fieldnames=[] # DictWriter will create a .csv with these header names
    
    for k,v in myDict.items():
        
        # is a dictionary?
        if (type(v) is dict):
            for kk,vv in v.items():
                print('k={0}, kk={1}, vv={2}'.format(k,kk,vv))
                name='{0}_{1}'.format(k,kk)
                fieldnames.append(name)
                newDict[name]=vv
                
        elif (type(v) is list):
            for item in range(len(v)):
                listItem=v.pop()
                if (type(listItem) is dict):
                    for kk,vv in listItem.items():
                        name='{0}_{1}'.format(k,kk)
                        fieldnames.append(name)
                        newDict[name]=vv
        
        else:
            print('k=[{0}] , v=[{1}]'.format(k,v))
            fieldnames.append(k)
            newDict[k]=v
    
    return fieldnames, newDict


# create fieldnames from the dictionary with lists and dictionaries
fieldnames, newDict=generateFieldnames(myDict)
pp.pprint(fieldnames)
print('\n')
pp.pprint(fieldnames)
print('\n\n')

# write a sample .csv with fieldnames as headers
fd = open('mytest.csv','a')
dw = csv.DictWriter( fd, fieldnames=fieldnames)

dw.writeheader() # write the header row

dw.writerow( newDict )
dw.writerow( newDict )
dw.writerow( newDict )

fd.close()