Author bjack205
2 Stars
Updated Last
2 Years Ago
Started In
April 2020

Build Status


This package is built to output tabularized logging information from possibly different levels during an optimization solve. Each logging level has an associated set of fields that can be written to between outputs to the terminal, when all the fields are printed on a single line.

Getting Started

Starting with a Empty Solver

The easiest way to get started is by building a solver with "empty" levels.

logger = SolverLogger(InnerLoop)
add_level!(logger, InnerLoop, print_color=:green, indent=4)
add_level!(logger, OuterLoop, print_color=:yellow)

The first line creates a new SolverLogger with a minimum print level of InnerLoop. The next two lines "register" two different log levels with the logger, and specify the color and indentation of the output.

We can now log a few pieces of data we'd like to output at the current iteration

with_logger(logger) do
    @logmsg InnerLoop :iter value=1 width=4
    @logmsg InnerLoop :cost value=10.2 width=10
    @logmsg InnerLoop :violation value=0.2 width=12
    @logmsg InnerLoop "first iteration"


Here we're specifying that the data correspond to the log level InnerLoop, followed by the name of the field, and then it's value and width. The last log event corresponds to the special "info" field that is used whenever a string is passed instead of a symbol.

We now print the header row and the data row by specifying the log level we wish to print:

print_header(logger, InnerLoop)
print_row(logger, InnerLoop)


This prints the current data to the console and caches the current values. We can now add data for the next iteration and print again:

with_logger(logger) do
    @logmsg InnerLoop :iter value=2
    @logmsg InnerLoop :violation value=0.1
print_row(logger, InnerLoop)


Note that we don't have to send data to every field: if nothing is sent it will simply print blank.

Let's say we now want to log a new piece of information and want it to print second. We can do this by simply logging the new field and using the loc keyword that specifies the column of the new entry

with_logger(logger) do
    @logmsg InnerLoop :iter value=3
    @logmsg InnerLoop :violation value=0.1
    @logmsg InnerLoop :first value=2 width=10 loc=2
print_header(logger, InnerLoop)
print_row(logger, InnerLoop)


Additional Log Levels

We can, at any time, log information to a different level:

with_logger(logger) do
    @logmsg OuterLoop :iter value=1 width=4
    @logmsg OuterLoop :total value=4 width=4
    @logmsg OuterLoop "outer loop"
    @logmsg OuterLoop "something happened"
print_header(logger, OuterLoop)
print_row(logger, OuterLoop)


Here we simply log a different level with new fields and widths and request to print the new level. Note that the special "info" field can be sent multiple strings, which are simply joined when sent to the output. All other fields replace the current data if the are written to more than once between output events.

Unregistered Log Levels

If a log level is used that isn't "registered" with the logger, it is sent to logger.default_logger.

@info "Something interesting"

The default logger can be changed using the corresponding keyword argument:

SolverLogger(minlevel, default_logger=ConsoleLogger(stderr, minlevel))

Accessing the Cached Values

By default, the logger will cache all the data sent to the output. This can be useful if you want to generate a plot of the values per iteration at the end of the solve. If we want all the cost values for the inner loop we can retrieve them with:


The cache can be cleared for a given level using


More Examples

See examples/ for more examples.

Required Packages