使用pandas的
first_valid_index()
方法获取某一列第一个非空值的索引,如何只移动该列的一个单独值而不是整个列。例如:data = {'year': [2010, 2011, 2012, 2013, 2014, 2015, 2016,2017, 2018, 2019],
'columnA': [10, 21, 20, 10, 39, 30, 31,45, 23, 56],
'columnB': [None, None, None, 10, 39, 30, 31,45, 23, 56],
'total': [100, 200, 300, 400, 500, 600, 700,800, 900, 1000]}
df = pd.DataFrame(data)
df = df.set_index('year')
print df
columnA columnB total
year
2010 10 NaN 100
2011 21 NaN 200
2012 20 NaN 300
2013 10 10 400
2014 39 39 500
2015 30 30 600
2016 31 31 700
2017 45 45 800
2018 23 23 900
2019 56 56 1000
for col in df.columns:
if col not in ['total']:
idx = df[col].first_valid_index()
df.loc[idx, col] = df.loc[idx, col] + df.loc[idx, 'total'].shift(1)
print df
AttributeError: 'numpy.float64' object has no attribute 'shift'
期望结果:
print df
columnA columnB total
year
2010 10 NaN 100
2011 21 NaN 200
2012 20 NaN 300
2013 10 310 400
2014 39 39 500
2015 30 30 600
2016 31 31 700
2017 45 45 800
2018 23 23 900
2019 56 56 1000