我有事故資料，其中部分資料包括事故發生的年份、受傷程度和受傷人員的年齡。這是 DataFrame 的一個示例：
df = pd.DataFrame({'Year': ['2010', '2010','2010','2010','2010','2011','2011','2011','2011'],
'Degree_injury': ['no_injury', 'death', 'first_aid', 'minor_injury','disability','disability', 'disability', 'death','first_aid'],
'Age': [50,31,40,20,45,29,60,18,48]})
print(df)
當年齡小于 40 歲時，我希望將三個輸出變數按年份分組在表中，并計算殘疾人數、死亡人數和輕傷人數。
輸出應該是這樣的：
當年齡小于 40 時，我生成了三個變數（num_disability、num_death、num_minor_injury），如下所示。
disability_filt = (df['Degree_injury'] =='disability') &\
(df['Age'] <40)
num_disability = df[disability_filt].groupby('Year')['Degree_injury'].count()
death_filt = (df['Degree_injury'] == 'death')& \
(df['Age'] <40)
num_death = df[death_filt].groupby('Year')['Degree_injury'].count()
minor_injury_filt = (df['Degree_injury'] == 'death') & \
(df['Age'] <40)
num_minor_injury = df[minor_injury_filt].groupby('Year')['Degree_injury'].count()
如何將這些變陣列合在一張表中，如上表所示？
先感謝您，
uj5u.com熱心網友回復：
pivot_table根據您的條件過濾行后使用：
out = df[df['Age'].lt(40)].pivot_table(index='Year', columns='Degree_injury',
values='Age', aggfunc='count', fill_value=0)
print(out)
# Output:
Degree_injury death disability minor_injury
Year
2010 1 0 1
2011 1 1 0
uj5u.com熱心網友回復：
# prep data
df2 = df.loc[df.Age<40,].groupby("Year").Degree_injury.value_counts().to_frame().reset_index(level=0, inplace=False)
df2 = df2.rename(columns={'Degree_injury': 'Count'})
df2['Degree_injury'] = df2.index
df2
# Year Count Degree_injury
# death 2010 1 death
# minor_injury 2010 1 minor_injury
# death 2011 1 death
# disability 2011 1 disability
# pivot result
df2.pivot(index='Year',columns='Degree_injury')
# death disability minor_injury
# Year
# 2010 1.0 NaN 1.0
# 2011 1.0 1.0 NaN
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