Question

下面是我要迭代的数据的DataFrame列，

> incident_id                            int64 date                     
> object state                           object city_or_county          
> object address                         object n_killed                
> int64 n_injured                        int64 incident_url             
> object source_url                      object
> incident_url_fields_missing            bool congressional_district    
> float64 gun_stolen                     object gun_type               
> object incident_characteristics        object latitude                
> float64 location_description           object longitude              
> float64 n_guns_involved                float64 notes                  
> object participant_age                 object participant_age_group   
> object participant_gender              object participant_name        
> object participant_relationship        object participant_status      
> object participant_type                object sources                 
> object state_house_district            float64 state_senate_district  
> float64 dtype: object

和下面是我编写的代码

def count_entries(df,col_name):
    """ Return a dictionary with counts of occurrences as value for each key"""
    cols_count = {}
    col = df[col_name]
    for entry in col:
        if entry in cols_count.keys():
            cols_count[entry] += 1
        else:
            cols_count = 1
    return cols_count
result = count_entries(data, 'gun_stolen')
print (result)

Answer 1

您可以使用value_counts简化解决方案：

df = pd.DataFrame({
        'A':list('abcdef'),
         'F':list('aaabbc')
})

print (df)
   A  F
0  a  a
1  b  a
2  c  a
3  d  b
4  e  b
5  f  c

def count_entries(df,col_name):
    """ Return a dictionary with counts of occurrences as value for each key"""
    return df[col_name].value_counts().to_dict()

或使用collections.Counter：

from collections import Counter

def count_entries(df,col_name):
    """ Return a dictionary with counts of occurrences as value for each key"""
    return dict(Counter(df[col_name]))

result = count_entries(df, 'F')
print (result)
{'a': 3, 'b': 2, 'c': 1}

Answer 2

def count_entries(df,col_name):
    """ Return a dictionary with counts of occurrences as value for each key"""
    cols_count = {}
    col = df[col_name]
    for entry in col:
        if entry in cols_count.keys():
            cols_count[entry] += 1
        else:
            # you forgot the [entry] in else statement.
            cols_count[entry] = 1
    return cols_count
result = count_entries(data, 'gun_stolen')
print (result)

AttributeError：“ int”对象没有属性“ keys”

2 个答案: