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get_the_first_non_null_value_in_each_column

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get_the_first_non_null_value_in_each_column [2021/09/15 21:57] – [get the first value not equal to a number] rajuget_the_first_non_null_value_in_each_column [2021/09/15 22:02] – [Use case] raju
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 ===== Get the first non null value in each column ===== ===== Get the first non null value in each column =====
 ==== Task ==== ==== Task ====
-Get the first non null value in each column+Get the first non null value in each column.
  
 Corner cases: Corner cases:
Line 66: Line 66:
  
 ==== meta ==== ==== meta ====
-used | Python 3.9.4 and IPython 7.22.0+Used | Python 3.9.4 and IPython 7.22.0
  
 demonstrates | apply a function on each column of a dataframe after doing a groupby demonstrates | apply a function on each column of a dataframe after doing a groupby
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 ===== Get the first value not equal to a number ===== ===== Get the first value not equal to a number =====
 ==== Use case ==== ==== Use case ====
-One downside of using np.nan to denote missing values is that an integer column of a+One downside of using np.nan to denote a missing value is that an integer column of a
 dataframe gets "promoted" to a floating point column even if there is a single np.nan in it. dataframe gets "promoted" to a floating point column even if there is a single np.nan in it.
  
-A work around is to use a specific integer to denote missing values. For example if we expect+One work around is to use a specific integer to denote missing values. For example if we expect
 all integers to be positive, we can use -9999 to denote a missing value. Let's call this all integers to be positive, we can use -9999 to denote a missing value. Let's call this
-special integer NAN_INT +special integer NAN_INT.
-NAN_INT+
  
 ==== Task ==== ==== Task ====
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 <code> <code>
 $ ipython $ ipython
-Python 3.9.4 (default, Apr  9 2021, 11:43:21) [MSC v.1916 64 bit (AMD64)] 
-Type 'copyright', 'credits' or 'license' for more information 
-IPython 7.22.0 -- An enhanced Interactive Python. Type '?' for help. 
  
 In [1]: In [1]:
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 1    1    3      4 -9999 1    1    3      4 -9999
 </code> </code>
 +==== meta ====
 +Used | Python 3.9.4, IPython 7.22.0
 +
get_the_first_non_null_value_in_each_column.txt · Last modified: 2021/09/15 22:03 by raju