基于多个条件过滤 Dataframe 结果

Question

I am struggling with filtering dataframe results set based on multiple conditions and would appreciate your help on the case below.

In the example below I would like to filter based on two conditions in dataframe:

1. Column "Condition 1" = 1
2. Column "Condition 2" = 0

In the code I use the following logic to filter the results with "filt" variable:

filt = (df["Condition 1"] )== 1 & (df["Condition 2"] == 0)

Unfortunately, the two-condition filter does not yield the desired results. In fact, neither conditions 1 nor 2 are met in the output.

print(df.loc[filt, "Condition 3"])

An alternative approach that worked but I would like to avoid is to create a third condition where "Condition 1" - "Condition 2" = 1 and base a filter on it. This would look as follows:

filt2 = df["Condition 3"] == 1

print(df.loc[filt2, "Condition 3"])

Notice that in this case there is only one condition in the filter ("filt2") which eventually produces the expected results.

My questions are:

1. Is there a reason that the multiple (two) filters do not work in my example, while the single condition filter does? Is there something I am overlooking in the code?
2. Are there better and simpler solutions to the alternative approach used with creating a third condition?

PS: The code below on "filt" would also produce the expected results.

filt = df["Condition 1"] - df["Condition 2"] == 1

Answer 1

You should filter like this:

filt = df[(df["Condition 1"] == 1) & (df["Condition 2"] == 0)]

filt dataframe will contain the desired result