私はパンダのバグにぶつかったと思います。バグを確認するか、コードのどこにロジックエラーがあるのかを把握するのに役立つことを望んでいました。
私のコードは次のとおりです。
import pandas, numpy, StringIO
def sq_fixer(sr):
    sr = sr.where(sr != '20200229')
    ranks = sr.argsort().astype(float)
    ranks[ranks == -1] = numpy.nan
    return ','.join(ranks.astype(numpy.str))
def correct_date(sr):
    date_fixer = lambda x: pandas.datetime(x.year -100, x.month, x.day) if x > pandas.datetime.now() else x
    sr = pandas.to_datetime(sr).apply(date_fixer).astype(pandas.datetime)
    return sr 
txt = '''ID,RUN_START_DATE,PUSHUP_START_DATE,SITUP_START_DATE,PULLUP_START_DATE
1,2013-01-24,2013-01-02,,2013-02-03
2,2013-01-30,2013-01-21,2013-01-13,2013-01-06
3,2013-01-29,2013-01-28,2013-01-01,2013-01-29
4,2013-02-16,2013-02-12,2013-01-04,2013-02-11
5,2013-01-06,2013-02-07,2013-02-25,2013-02-12
6,2013-01-26,2013-01-28,2013-02-12,2013-01-10
7,2013-01-26,,2013-01-12,2013-01-30
8,2013-01-03,2013-01-24,2013-01-19,2013-01-02
9,2013-01-22,2013-01-13,2013-02-03,
10,2013-02-06,2013-01-16,2013-02-07,2013-01-11
3347,,2008-02-27,2008-04-10,2008-02-13 
3588,2004-09-12,,2004-11-06,2004-09-06 
3784,2003-02-22,,2003-06-21,2003-02-19 
593,2009-04-03,,2009-06-01,2009-04-01 
4148,2003-03-21,2002-09-20,2003-04-01,2003-01-01 
4299,2004-05-24,2004-07-23,,2004-04-22 
4590,2005-05-05,2005-12-05,2005-04-05,
4830,2001-06-12,2000-10-12,2001-07-28,2001-01-28 
4941,2006-11-08,2006-12-19,2006-07-19,2007-02-24 
1416,2004-04-03,2004-05-19,2004-02-06,
1580,2008-12-20,,2009-03-19,2008-12-19 
1661,2005-10-03,2005-10-26,2005-09-12,2006-02-19 
1759,2001-10-18,,2002-01-17,2001-10-17 
1858,2003-04-14,2003-05-17,,2002-12-17 
1972,2003-06-01,2003-07-14,2002-12-14,
5905,2000-11-18,2001-01-13,,2000-11-04 
2052,2002-06-11,,2002-08-23,2001-12-12 
2165,2006-10-01,,2007-02-27,2006-09-30 
2218,2007-09-19,,2008-02-06,2007-09-09 
2350,2000-08-08,,2000-09-22,2000-01-08 
2432,2001-08-22,,2001-09-25,2000-12-16 
2611,2005-05-07,,2005-06-05,2005-03-26 
2612,2005-05-06,,2005-05-26,2005-04-11 
7378,2009-08-07,2009-01-30,2010-01-20,2009-06-08 
7550,2006-04-08,,2006-06-01,2006-04-01  '''
df = pandas.read_csv(StringIO.StringIO(txt))
sequence_array = ['RUN_START_DATE', 'PUSHUP_START_DATE', 'SITUP_START_DATE', 'PULLUP_START_DATE']
xsequence_array = ['X_RUN_START_DATE', 'X_PUSHUP_START_DATE', 'X_SITUP_START_DATE', 'X_PULLUP_START_DATE']
df[sequence_array] = df[sequence_array].apply(correct_date, axis=1)
fix_day = lambda x: x if x > 0 else 29
fix_month = lambda x: x if x > 0 else 02
fix_year = lambda x: x if x > 0 else 2020
for col in sequence_array:
    xcol = 'X_{0}'.format(col)
    df[xcol] = ['{0:04d}{1:02d}{2:02d}'.format(fix_year(c.year), fix_month(c.month), fix_day(c.day)) for c in df[col]]
df['X_AS_SEQUENCE'] = df[xsequence_array].apply(sq_fixer, axis=1)
コードを実行すると、ほとんどの結果が正しいです。インデックス6を例にとってみましょう。
In [31]: df.ix[6]
Out[31]: 
ID                                       7
RUN_START_DATE         2013-01-26 00:00:00
PUSHUP_START_DATE                      NaN
SITUP_START_DATE       2013-01-12 00:00:00
PULLUP_START_DATE      2013-01-30 00:00:00
X_RUN_START_DATE                  20130126
X_PUSHUP_START_DATE               20200229
X_SITUP_START_DATE                20130112
X_PULLUP_START_DATE               20130130
X_AS_SEQUENCE              1.0,nan,0.0,2.0
ただし、特定のインデックスは、ループに対してpandas.argsort()をスローするようです。インデックス10を例にとってみましょう。
In [32]: df.ix[10]
Out[32]: 
ID                                    3347
RUN_START_DATE                         NaN
PUSHUP_START_DATE      2008-02-27 00:00:00
SITUP_START_DATE       2008-04-10 00:00:00
PULLUP_START_DATE      2008-02-13 00:00:00
X_RUN_START_DATE                  20200229
X_PUSHUP_START_DATE               20080227
X_SITUP_START_DATE                20080410
X_PULLUP_START_DATE               20080213
X_AS_SEQUENCE              nan,2.0,0.0,1.0
argsortは。nan,1.0,2.0,0.0の代わりに戻る必要がありnan,2.0,0.0,1.0ます。
私はこれを3日間続けています。この時点では、それが私なのかバグなのかわかりません。答えを得るためにそれをバックトレースする方法がわかりません。どんな助けでも大歓迎です!