Metadata-Version: 1.1
Name: Lifetimes
Version: 0.1.6.3
Summary: Measure customer lifetime value in Python
Home-page: https://github.com/CamDavidsonPilon/lifetimes
Author: Cam Davidson-Pilon
Author-email: cam.davidson.pilon@gmaillcom
License: MIT
Description: ![logo](http://i.imgur.com/7s3jqZM.png)
        
        #### Measuring users is hard. Lifetimes makes it easy. 
        [![Latest Version](https://pypip.in/v/lifetimes/badge.png)](https://pypi.python.org/pypi/lifetimes/)
        [![Build Status](https://travis-ci.org/CamDavidsonPilon/lifetimes.svg?branch=master)](https://travis-ci.org/CamDavidsonPilon/lifetimes)
        [![Coverage Status](https://coveralls.io/repos/CamDavidsonPilon/lifetimes/badge.svg?branch=master)](https://coveralls.io/r/CamDavidsonPilon/lifetimes?branch=master)
        
        ## Introduction
        
        Lifetimes can be used to analyze your users based on a few assumption:
        
        1. Users interact with you when they are "alive".
        2. Users under study may "die" after some period of time.
        
        I've quoted "alive" and "die" as these are the most abstract terms: feel free to use your own defintion of "alive" and "die" (they are used similarly to "birth" and "death" in survival analysis). Whenever we have individuals repeating occurrences, we can use Lifetimes to help understand user behaviour.
        
        ### Applications
        
        If this is too abstract, consider these applications:
        
         - Predicting how often a visitor will return to your website. (Alive = visiting. Die = decided the website wasn't for them)
         - Understanding how frequently a patient may return to a hospital. (Alive = visiting. Die = maybe the patient moved to a new city, or became deceased.)
         - Predicting individuals who have churned from an app using only their usage history. (Alive = logins. Die = removed the app)
         - Predicting repeat purchases from a customer. (Alive = actively purchasing. Die = became disinterested with your product)
         - Predicting the lifetime values of your customers
         
        ### Specific Application: Customer Lifetime Value
        As emphasized by P. Fader and B. Hardie, understanding and acting on customer lifetime value (CLV) is the most important part of your business's sales efforts. [And (apparently) everyone is doing it wrong](https://www.youtube.com/watch?v=guj2gVEEx4s). *Lifetimes* is a Python library to calculate CLV for you.
         
        
        ## Installation
        
            pip install lifetimes
        
        Requirements are only Numpy, Scipy, Pandas (and optionally-but-seriously matplotlib). 
        
        ## Quickstart
        
        For the following examples, we'll use a dataset from an ecommerce provider to analyze their customers' repeat purchases. The examples below are using the `cdnow_customers.csv` located in the `datasets/` directory.
        
            from lifetimes.datasets import load_cdnow
            data = load_cdnow(index_col=[0])
            data.head()
            """
                 frequency   recency      T
            ID 
            1    2           30.43       38.86
            2    1            1.71       38.86
            3    0            0.00       38.86
            4    0            0.00       38.86
            5    0            0.00       38.86
            """
        
        `frequency` represents the number of repeat purchases the customer has made. `T` represents the age of the customer. `recency` represents the age of the customer when they made their most recent purchases.
        
        #### Fitting models to our data
        
        We'll use the **BG/NBD model** first. Interested in the model? See this [nice paper here](http://mktg.uni-svishtov.bg/ivm/resources/Counting_Your_Customers.pdf). 
        
            from lifetimes import BetaGeoFitter
        
            # similar API to scikit-learn and lifelines.
            bgf = BetaGeoFitter(penalizer_coef=0.0)
            bgf.fit(data['frequency'], data['recency'], data['T'])
            print bgf
            """
            <lifetimes.BetaGeoFitter: fitted with 2357 subjects, a: 0.79, alpha: 4.41, r: 0.24, b: 2.43>
            """
        
        After fitting, we have lots of nice methods and properties attached to the fitter object.
        
        #### Visualizing our Frequency/Recency Matrix
        
        Consider: a customer bought from you every day for three weeks straight, and we haven't heard from them in months. What are the chances they are still "alive"? Pretty small. On the other hand, a customer who historically buys from you once a quarter, and bought last quarter, is likely still alive. We can visualize this relationship using the **Frequency/Recency matrix**, which computes the expected number of transactions a artifical customer is to make in the next time period, given his or her recency (age at last purchase) and frequency (the number of repeat transactions he or she has made).
        
            from lifetimes.plotting import plot_frequency_recency_matrix
        
            plot_frequency_recency_matrix(bgf)
        
        ![fr_matrix](http://i.imgur.com/oYfTH0Dl.png)
        
        
        We can see that if a customer has bought 25 times from you, and their lastest purchase was when they were 35 weeks old (given the individual is 35 weeks old), then they are you best customer (bottom-right). You coldest customers are those that in the top-right corner: they bought a lot quickly, and we haven't seen them in weeks. 
        
        There's also that beautiful "tail" around (5,25). That represents the customer who buys infrequently, but we've seen him or her recently, so they *might* buy again - we're not sure if they are dead or just between purchases. 
        
        Another interesting matrix to look at is the probability of still being *alive*:
        
            from lifetimes.plotting import plot_probability_alive_matrix
        
            plot_probability_alive_matrix(bgf)
        
        ![prob](http://i.imgur.com/qjellK6l.png)
        
        #### Ranking customers from best to worst
        
        Let's return to our customers and rank them from "highest expected purchases in the next period" to lowest. Models expose a method that will predict a customer's expected purchases in the next period using their history.
        
            t = 1
            data['predicted_purchases'] = data.apply(lambda r: bgf.conditional_expected_number_of_purchases_up_to_time(t, r['frequency'], r['recency'], r['T']), axis=1)
            data.sort('predicted_purchases').tail(5)
            """
                   frequency  recency      T        predicted_purchases
            ID
            509   18          35.14        35.86    0.424877
            841   19          34.00        34.14    0.474738
            1981  17          28.43        28.86    0.486526
            157   29          37.71        38.00    0.662396
            1516  26          30.86        31.00    0.710623
            """
        
        Great, we can see that the customer who has made 26 purchases, and bought very recently from us, is probably going to buy again in the next period. 
        
        #### Assessing model fit
        
        Ok, we can predict and we can visualize our customers' behaviour, but is our model correct? There are a few ways to assess the model's correctness. The first is to compare your data versus artifical data simulated with your fitted model's parameters. 
        
            from lifetimes.plotting import plot_period_transactions
            plot_period_transactions(bgf)
        
        ![model_fit_1](http://imgur.com/4P6AfsQl.png)
        
        We can see that our actual data and our simulated data line up well. This proves that our model doesn't suck.
        
        #### Example using transactional datasets
        
        Most often, the dataset you have at hand will be at the transaction level. Lifetimes has some utility functions to transform that transactional data (one row per purchase) into summary data (a frequency, recency and age dataset).
        
            from lifetimes.datasets import load_transaction_data
            from lifetimes.utils import summary_data_from_transaction_data
        
            transaction_data = load_transaction_data()
            transaction_data.head()
            """
                              date  id
            0  2014-03-08 00:00:00   0
            1  2014-05-21 00:00:00   1
            2  2014-03-14 00:00:00   2
            3  2014-04-09 00:00:00   2
            4  2014-05-21 00:00:00   2
            """
        
            summary = summary_data_from_transaction_data(transaction_data, 'id', 'date', observation_period_end='2014-12-31')
        
            print summary.head()
            """
                frequency  recency    T
            id
            0           0        0  298
            1           0        0  224
            2           6      142  292
            3           0        0  147
            4           2        9  183
            """
        
            bgf.fit(summary['frequency'], summary['recency'], summary['T'])
            # <lifetimes.BetaGeoFitter: fitted with 5000 customers, a: 1.85, alpha: 1.86, r: 0.16, b: 3.18>
        
        #### More model fitting
        
        With transactional data, we can partition the dataset into a calibration period dataset and a holdout dataset. This is important as we want to test how our model performs on data not yet seen (think cross-validation in standard machine learning literature). Lifetimes has a function to partition our dataset like this:
        
            from lifetimes.utils import calibration_and_holdout_data
        
            summary_cal_holdout = calibration_and_holdout_data(transaction_data, 'id', 'date', 
                                                    calibration_period_end='2014-09-01',
                                                    observation_period_end='2014-12-31' )   
            print summary_cal_holdout.head()
            """
                frequency_cal  recency_cal  T_cal  frequency_holdout  duration_holdout
            id
            0               0            0    177                  0               121
            1               0            0    103                  0               121
            2               6          142    171                  0               121
            3               0            0     26                  0               121
            4               2            9     62                  0               121
            """
        
        With this dataset, we can perform fitting on the `_cal` columns, and test on the `_holdout` columns:
        
            from lifetimes.plotting import plot_calibration_purchases_vs_holdout_purchases
        
            bgf.fit(summary_cal_holdout['frequency_cal'], summary_cal_holdout['recency_cal'], summary_cal_holdout['T_cal'])
            plot_calibration_purchases_vs_holdout_purchases(bgf, summary_cal_holdout)
        
        ![holdout](http://imgur.com/LdSEYUwl.png)
        
        #### Customer Predicitions
        
        Based on customer history, we can predict what an individuals future purchases might look like:
        
            t = 10 #predict purchases in 10 periods
            individual = summary.iloc[20]
            # The below function is an alias to `bfg.conditional_expected_number_of_purchases_up_to_time`
            bgf.predict(t, individual['frequency'], individual['recency'], individual['T'])
            # 0.0576511
        
        
        ### Customer Probability Histories
        
        Given a customer transaction history, we can calculate their historical probability of being alive, according to 
        our trained model. For example:
        
            from lifetimes.plotting import plot_history_alive
        
            id = 35
            days_since_birth = 200
            sp_trans = transaction_data.ix[transaction_data['id'] == id]
            plot_history_alive(bgf, days_since_birth, sp_trans, 'date')
        
        ![history](http://i.imgur.com/y45tum4.png)
        
        ### Estimating Customers' Lifetime Value
        
        For this whole time we didn't take into account the economic value of each transaction and we focused mainly on
        transactions' occurrences. To estimate this we can use the Gamma-Gamma submodel. But first we need to create summary data
        from transactional data also containing economic values for each transaction (i.e. profits or revenues).
        
            from lifetimes.datasets import load_summary_data_with_monetary_value
        
            summary_with_money_value = load_summary_data_with_monetary_value()
            summary_with_money_value.head()
            returning_customers_summary = summary_with_money_value[summary_with_money_value['frequency']>0]
            
            returning_customers_summary.head()
            """
            	frequency	recency	T	monetary_value
            id				
            2	1	        0	    262	44.500000
            3	2	        90	    272	20.353333
            4	2	        213	    273	24.673333
            5	7	        257	    273	32.651250
            8	3	        183	    273	26.447500
            """
        
        #### The Gamma-Gamma model and the independence assumption
        The model we are going to use to estimate the CLV for our userbase is called the Gamma-Gamma submodel, 
        which relies upon an important assumption. The Gamma-Gamma submodel, in fact, assumes that there is no 
        relationship between the monetary value and the purchase frequency. In practice we need to check whether 
        the Pearson correlation between the two vectors is close to 0 in order to use this model.
        
            returning_customers_summary[['monetary_value', 'frequency']].corr()
            """
                            monetary_value	frequency
            monetary_value	1.000000	    0.070505
            frequency	    0.070505	    1.000000
            """
        
        At this point we can train our Gamma-Gamma submodel and predict the conditional, expected average lifetime value of our customers.
        
            ggf = GammaGammaFitter(penalizer_coef = 0)
            ggf.fit(returning_customers_summary['frequency'], 
                    returning_customers_summary['monetary_value'])
            print ggf    
            """
            <lifetimes.GammaGammaFitter: fitted with 9591 subjects, p: 163.91, q: 7.36, v: 0.06>
            """
            
        We can now produce the average CLV figure for our dataset as follows:
            
            print "Expected conditional average profit: %s, Average profit: %s" % (
                ggf.conditional_expected_average_profit(
                    returning_customers_summary['frequency'], 
                    returning_customers_summary['monetary_value']
                ), 
                summary_with_money_value[summary_with_money_value['frequency']>0]['monetary_value'].mean()
            )
            """
            Expected conditional average profit: 34.4038955386, Average profit: 35.1922197294
            """
        
        While for computing the total CLV using the DCF method (https://en.wikipedia.org/wiki/Discounted_cash_flow) adjusting for cost of capital:
         
            print ggf.customer_lifetime_value(
                bgf, #the model to use to predict the number of future transactions
                returning_customers_summary['frequency'],
                returning_customers_summary['recency'],
                returning_customers_summary['T'], 
                returning_customers_summary['monetary_value'], 
                time=12, 
                discount_rate=0.7
            ) #10689.30
        
        ## Questions? Comments? 
        
        Drop me a line at [`@cmrn_dp`](https://twitter.com/Cmrn_DP)! 
        
        
        ## More Information
        
        1. [Roberto Medri](http://cdn.oreillystatic.com/en/assets/1/event/85/Case%20Study_%20What_s%20a%20Customer%20Worth_%20Presentation.pdf) did a nice presentation on CLV at Etsy.
        2. [Papers](http://mktg.uni-svishtov.bg/ivm/resources/Counting_Your_Customers.pdf), lots of [papers](http://brucehardie.com/notes/009/pareto_nbd_derivations_2005-11-05.pdf).
        3. R implementation is called [BTYD](http://cran.r-project.org/web/packages/BTYD/vignettes/BTYD-walkthrough.pdf) (for, *Buy Til You Die*).
        
        
Keywords: customer lifetime value,clv,ltv,BG/NBD,pareto/NBD,frequency,recency
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python
Classifier: Topic :: Scientific/Engineering
