logger.md

Logger

optim provides also logging and live plotting capabilities via the optim.Logger() function.

Live logging is essential to monitor the network accuracy and cost function during training and testing, for spotting under- and over-fitting, for early stopping or just for monitoring the health of the current optimisation task.

Logging data

Let walk through an example to see how it works.

We start with initialising our logger connected to a text file accuracy.log.

logger = optim.Logger('accuracy.log')

We can decide to log on it, for example, training and testing accuracies.

logger:setNames{'Training acc.', 'Test acc.'}

And now we can populate our logger randomly.

for i = 1, 10 do
   trainAcc = math.random(0, 100)
   testAcc = math.random(0, 100)
   logger:add{trainAcc, testAcc}
end

We can cat accuracy.log and see what's in it.

Training acc.   Test acc.
 7.0000e+01      5.9000e+01
 7.6000e+01      8.0000e+00
 6.6000e+01      3.4000e+01
 7.4000e+01      4.3000e+01
 5.7000e+01      1.1000e+01
 5.0000e+00      9.8000e+01
 7.1000e+01      1.7000e+01
 9.8000e+01      2.7000e+01
 3.5000e+01      4.7000e+01
 6.8000e+01      5.8000e+01

Visualising logs

OK, cool, but how can we actually see what's going on?

To have a better grasp of what's happening, we can plot our curves. We need first to specify the plotting style, choosing from:

• . for dots
• + for points
• - for lines
• +- for points and lines
• ~ for using smoothed lines with cubic interpolation
• | for using boxes
• custom string, one can also pass custom strings to use full capability of gnuplot.

logger:style{'+-', '+-'}
logger:plot()

If we'd like an interactive visualisation, we can put the logger:plot() instruction within the for loop, and the chart will be updated at every iteration.

In case we'd like to prevent gnuplot to display the plots, we can set the option logger:display(false). In this way, plots will be saved but not displayed. To restore the normal behaviour, use logger:display(true).

We can set a logarithmic y axis with logger:setlogscale(true) and reset it with logger:setlogscale(false).