A simple single-class function that calculate an amount adjusted for inflation (or grab it from the bls.gov website it you prefer to wait).
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examples.php
inflation.php
readme.md

readme.md

Inflation Class

A simple PHP function to either calculate inflation locally or to scrape the http://data.bls.gov/ inflation calculator for the adjustment.

Requirements

This function requires cURL access if you wish to scrape the bls.gov calculator for your answer.

Usage

After including the class call one of the following functions:

  • adjust($amount,$in_year,[$like_year],[$round_to]) will adjust the $ammount as if was in $in_year like it was $like_year. With this function you do not need to call the $like_year, if you lave it absent it will automatically fill it for the latest possible date (the last month of the last year of data). This function uses the internal CPI data table and therefore can do inflation down to the month. Various month formats should be usable, but it only supports month and year combinations (like 10/1999 or 1987-4). Passing the optional $round_to variable will adjust the number of places after the decimal. This will return the adjusted value of today and throw a notice if there was an error.

  • grabAdjustment($ammount,$in_year,[$like_year]) will adjust the $ammount as if was in $in_year like it was $like_year. Like with the above if you omit the $like_year it will pull for the current year. Since this one puuls from the CPI calculator is cannot do to-the-month adjustments. This will return the adjusted amount or an error message. This is a static function so it can be called directly, but it is also substantially slower because it has to cURL the bls.gov website for the information and for that reason is not recommended.

  • data_updated() will return the last time the data was updated in a user readable format (ie December 2014).

Example useage can be found in examples.php.

About the data

The data used in internal calculations is gathered from the latest report from http://www.bls.gov/cpi/tables.htm in Table 24. It is stored in a multi-dimensional array in a array($year => array($avg, $jan, $feb...),... format. This class will most likely not be updated on a monthly basis as new information is added, and the data does not seem to be updated on a monthly basis, but adding new months of data is simple. If you do go ahead and add new data submit a pull request and I'll incorporate it into the main repository.