熊猫数据框比较

Question

I am learning Pandas dataframes for a project and having trouble understanding some of the operators and how I can use them. In one case, I have one dataframe for production data and another for targets. I can get the items in the production data that met the targets and those that didn't using:

good = prod['A'][prod['A'] >= target['A']]
bad = prod['A'][prod['A'] < target['A']]

and it works well. But in some cases, I have an upper and lower target, which is where I am getting stuck. I need to find the values that are above the upper target, the values below the lower target and the values that were in between and get 3 separate dataframes. I tried what seemed obvious working with normal lists:

aboveTargetA = prod['A'][prod['A'] >= targetA['A']]
belowTargetB = prod['A'][prod['A'] <= targetB['A']]
betweenTargets = prod[[col for index, col in df.iterrows() if col not in aboveTargetA and col not in belowTargetB]]

I'm not sure how I should be doing it with these dataframes and generators as I have never worked with them before. Can anyone point me in the right direction for the comparisons?

Answer 1

You can do boolean indexing with multiple conditions:

prod['A'][(prod['A'] < targetA['A']) & (prod['A'] > targetB['A'])]

See also http://pandas.pydata.org/pandas-docs/dev/indexing.html#boolean-indexing