Changes between Version 2 and Version 3 of udg/ecoms/RPackage/examples/visualization


Ignore:
Timestamp:
May 13, 2016 5:04:47 PM (6 years ago)
Author:
juaco
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • udg/ecoms/RPackage/examples/visualization

    v2 v3  
    9898
    9999
     100We next show different forecast visualization plots:
    100101
     102
     103
     104== Tercile plot
     105
     106Tercile plots are very useful in order to obtain a quick overview of the overall skill of the predictions over a region of interest.
     107
     108{{{#!text/R
     109tercilePlotS4(prd, obs, year.target, detrend = TRUE, color.pal = "bw")
     110## Warning messages:
     111## 1: In spatialMean(mm.obj) :
     112##   The results presented are the spatial mean of the input field
     113## 2: In spatialMean(obs) :
     114##   The results presented are the spatial mean of the input field
     115}}}
     116
     117[[Image(image-20160513-164440.png)]]
     118
     119
     120For each member, the daily predictions are averaged to obtain a single seasonal forecast (this yields a first warning, as in this example). For rectangular spatial domains (i.e., for grids), the spatial average is first computed (with a warning) to obtain a unique series for the whole domain, as in this example. The corresponding terciles for each ensemble member are then computed for the analysis period. Thus, data is converted converted to a series of tercile categories by considering values above, between or below the terciles of the whole period. The probability of a member to fall into the observed tercile is represented by the colorbar (different color palettes are available through the argument `color.pal`). For instance, probabilities below 1/3 are very low, indicating that a minority of the members falls in the tercile. Conversely, probabilities above 2/3 indicate a high level of member agreement (more than 66% of members falling in the same tercile). The observed terciles (the events that actually occurred) are represented by the white circles.
     121
     122Finally, the ROC Skill Score (ROCSS) is indicated in the secondary (right) Y axis. For each tercile, it provides a quantitative measure of the forecast skill, and it is commonly used to evaluate the performance of probabilistic systems. The value of this score ranges from 1 (perfect forecast system) to -1 (perfectly bad forecast system). A value zero indicates no skill compared with a random prediction.
     123
     124
     125== Bubble plots
     126
     127
     128While the tercile plot provides an areal overview, to focus on particular regions bubble plots are very useful. First of all, we select a target year for which the predictions are to be analysed:
     129
     130{{{#!text/R
     131year.target <- 1995
     132bubblePlotS4(prd,
     133             obs,
     134             piechart = TRUE,
     135             year.target,
     136             detrend = FALSE,
     137             size.as.probability = TRUE,
     138             score = TRUE,
     139             color.reverse = TRUE)
     140}}}
     141
     142
     143[[Image(image-20160513-165428.png)]]
     144
     145
     146
     147The bubble plot represents the most likely tercile in colors, the probability of that tercile with the size of the bubble (optional) and the skill of the forecast system for that tercile as transparency of the bubble (optional). Currently, the skill score used is the ROCSS. Pie charts instead of bubbles can be drawn indicating the predicted likelihood of each tercile, as in this example (using the `piechart=TRUE` option).
     148
     149
     150Using the bubble plot allows for instance to test the effrect of data detrending, as we suggested in the previous example that may be the source of some -artificial- skill in the north-eastern sector of the study area. We control this through the logical argument `detrend`:
     151
     152
     153{{{#!text/R
     154bubblePlotS4(prd,
     155             obs,
     156             piechart = TRUE,
     157             year.target,
     158             detrend = TRUE,
     159             score = TRUE,
     160             color.reverse = TRUE)
     161}}}
     162
     163[[Image(image-20160513-170153.png)]]
     164
     165