10.5.1 The Stats Class
Keywords: lib

##
10.5.1 The `Stats` Class

`Stats` objects have the following methods:

`strip_dirs`()
  This method for the `Stats` class removes all leading path information from file names. It is very useful in reducing the size of the printout to fit within (close to) 80 columns. This method modifies the object, and the stripped information is lost. After performing a strip operation, the object is considered to have its entries in a ``random'' order, as it was just after object initialization and loading. If `strip_dirs()` causes two function names to be indistinguishable (they are on the same line of the same filename, and have the same function name), then the statistics for these two entries are accumulated into a single entry.

`add`(filename[, ...])
  This method of the `Stats` class accumulates additional profiling information into the current profiling object. Its arguments should refer to filenames created by the corresponding version of `profile.run()`. Statistics for identically named (re: file, line, name) functions are automatically accumulated into single function statistics.

`sort_stats`(key[, ...])
  This method modifies the `Stats` object by sorting it according to the supplied criteria. The argument is typically a string identifying the basis of a sort (example: `'time'` or `'name'`).

  When more than one key is provided, then additional keys are used as secondary criteria when the there is equality in all keys selected before them. For example, "`sort_stats('name', 'file')`" will sort all the entries according to their function name, and resolve all ties (identical function names) by sorting by file name.

  Abbreviations can be used for any key names, as long as the abbreviation is unambiguous. The following are the keys currently defined:

  Valid Arg | Meaning
  --- | ---
  `'calls'` | call count
  `'cumulative'` | cumulative time
  `'file'` | file name
  `'module'` | file name
  `'pcalls'` | primitive call count
  `'line'` | line number
  `'name'` | function name
  `'nfl'` | name/file/line
  `'stdname'` | standard name
  `'time'` | internal time

  Note that all sorts on statistics are in descending order (placing most time consuming items first), where as name, file, and line number searches are in ascending order (alphabetical). The subtle distinction between `'nfl'` and `'stdname'` is that the standard name is a sort of the name as printed, which means that the embedded line numbers get compared in an odd way. For example, lines 3, 20, and 40 would (if the file names were the same) appear in the string order 20, 3 and 40. In contrast, `'nfl'` does a numeric compare of the line numbers. In fact, `sort_stats('nfl')` is the same as `sort_stats('name', 'file', 'line')`.

  For compatibility with the old profiler, the numeric arguments `-1`, `0`, `1`, and `2` are permitted. They are interpreted as `'stdname'`, `'calls'`, `'time'`, and `'cumulative'` respectively. If this old style format (numeric) is used, only one sort key (the numeric key) will be used, and additional arguments will be silently ignored.

`reverse_order`()
  This method for the `Stats` class reverses the ordering of the basic list within the object. This method is provided primarily for compatibility with the old profiler. Its utility is questionable now that ascending vs descending order is properly selected based on the sort key of choice.

`print_stats`([restriction, ...])
  This method for the `Stats` class prints out a report as described in the `profile.run()` definition.

  The order of the printing is based on the last `sort_stats()` operation done on the object (subject to caveats in `add()` and `strip_dirs()`).

  The arguments provided (if any) can be used to limit the list down to the significant entries. Initially, the list is taken to be the complete set of profiled functions. Each restriction is either an integer (to select a count of lines), or a decimal fraction between 0.0 and 1.0 inclusive (to select a percentage of lines), or a regular expression (to pattern match the standard name that is printed; as of Python 1.5b1, this uses the Perl-style regular expression syntax defined by the `re` module). If several restrictions are provided, then they are applied sequentially. For example:

        print_stats(.1, 'foo:')

  would first limit the printing to first 10% of list, and then only print functions that were part of filename "`.*foo:`". In contrast, the command:

        print_stats('foo:', .1)

  would limit the list to all functions having file names "`.*foo:`", and then proceed to only print the first 10% of them.

`print_callers`([restriction, ...])
  This method for the `Stats` class prints a list of all functions that called each function in the profiled database. The ordering is identical to that provided by `print_stats()`, and the definition of the restricting argument is also identical. For convenience, a number is shown in parentheses after each caller to show how many times this specific call was made. A second non-parenthesized number is the cumulative time spent in the function at the right.

`print_callees`([restriction, ...])
  This method for the `Stats` class prints a list of all function that were called by the indicated function. Aside from this reversal of direction of calls (re: called vs was called by), the arguments and ordering are identical to the `print_callers()` method.

`ignore`()
  Deprecated since release 1.5.1. This is not needed in modern versions of Python.10.2

#### Footnotes

... Python.10.2
  This was once necessary, when Python would print any unused expression result that was not `None`. The method is still defined for backward compatibility.