Python information and short questions megathread.

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axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

I'm using pandas to update a column in a dataframe.

My rules are if there is a value in the New column, that becomes the Current value.

If there is a NaN in the New column, the value in the Old column becomes the Current value

code:

In[]: df = pd.DataFrame([[1, 2,np.nan],[3, 2,np.nan],[7, np.nan,np.nan], [np.nan, 8,np.nan]], columns=['Old', 'New', 'Current'])
In[]: df
Out[]: 

   Old  New  Current
0  1.0  2.0      NaN
1  3.0  2.0      NaN
2  7.0  NaN      NaN
3  NaN  8.0      NaN

I try to put in the values from New and then replace the NaN from Old.

code:

In[]df.Current=df.New
In[]df.Current=df.Current.loc[(df.Current.isnull() & (df.Old.notnull()))] = df.Old
In[]df
Out[]: 

   Old  New  Current
0  1.0  2.0      1.0
1  3.0  2.0      3.0
2  7.0  NaN      7.0
3  NaN  8.0      NaN

Welp, this just replaces all the values in Current with Old.

Please help, I'm bad and new at this.

# ¿ Nov 18, 2016 18:00

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# ¿ May 29, 2024 08:06

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

Eela6 posted:

vikingstrike posted:

Cingulate posted:

Xeno54 posted:

Thanks a lot for your help :tipshat:

# ¿ Nov 21, 2016 13:33

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