python - Dataframe Boolean Logic Index Match -
i have created pandas data frame , filter data based on boolean logic. i'd closer excels' index match function simple filtering. have researched lot of other threads.
when apply filter, data frame returns 0 true values. why 0 true values being returned when have been flexible logic? and;
if introduced 5th column, column
'd',random.randomint(100-1000,100), logic use conditionally find maximum values columnd? i.e. can force data frame return highest true values column, in event multiple true values returned?
advice appreciated. thank in advance.
import pandas pd df = pd.dataframe({ 'step': [1,1,1,1,1,1,2,2,2,2,2,2], 'a': [4,5,6,7,4,5,6,7,4,5,6,7], 'b': [10,20,30,40,10,20,30,40,10,20,30,40], 'c': [0,0.5,1,1.5,2,2.5,0,0.5,1,1.5,2.0,2.5] }) columns = ['step','a','b','c'] df=df[columns] new_df=df[(df.step == 1) & (df.a == 4|5|6|7) & (df.b == 10|20|30|40)] new_df
using dataframe.query() method:
in [7]: new_df = df.query("step==1 , in [4,5,6,7] , b in [10,20,30,40]") in [8]: new_df out[8]: step b c 0 1 4 10 0.0 1 1 5 20 0.5 2 1 6 30 1.0 3 1 7 40 1.5 4 1 4 10 2.0 5 1 5 20 2.5 
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