Prediction of Fire Occurrence in Algeria’s Forest

Machine Learning
Logistic Regression
PCA
Author

Olamide Adu

Published

August 4, 2024

Introduction

According to the World Bank, Algeria’s forest is about 0.82% of the total country’s land mass in 2021 (tradingeconomics.com). Algeria is one of the Maghreb countries affected by wildfire. Given the troubles associated with wildfire, it is important to assess and predict the potential for wildfire activity. One of the ways to predict the potential for wildfire is associating its occurrence with weather conditions. This is called the Fire Weather Index (FWI). FWI was developed by the Canadian Forest Service and it is a key component of the Canadian Forest Fire Weather Index System. FWI is also used internationally to assess fire danger and predict wildfire behavior based on weather conditions. Forest Fire - source:aljazeer.com

Objective

For this project, I will predict the occurrence of fire (fire or nor fire) given a set of parameters related to FWI in two regions of Algeria, the Bejaia region located in the northeast of Algeria and Sidi Bel-abbes region located in the northwest of Algeria.

Data

The data for this analysis is collected from UCI machine learning data repository and provided by (Abid and Izeboudjen 2020). The variables include:

Variable name Data type Definition
region categorical area in Algeria, either of Sidi Bel-abbes or Bejaia
day date the day in number
month date month of the year, from June to September
year date single year of when data as observed
temp numeric max noon temperature in \(^{\circ}C\)
rh numeric relative humidity in percentage
ws numeric wind speed in km/h
rain numeric total rain in a day in mm
ffmc numeric fine fuel moisture code
dmc numeric Duff moisture code
dc numeric drought code
isi numeric Initial spread index
bui numeric buildup index
fwi numeric fire weather index
classes binary class of fire occurrence. This is the target variable

To get started I load all necessary packages. Tidyverse for all forms of data manipulation, visualization and data importation and tidymodels for our model workflow.

Show the code 
library(pacman)
p_load(tidyverse, tidymodels, knitr, ggthemes, hrbrthemes)
theme_set(theme_ipsum_ps(base_size = 12))

I like using the pacman package instead of using base R’s library() function because it simplifies library management and integration. Another packagem management system is pkgdown.

Next I import the data

Show the code 
algeria_ff <- read_csv("data/Algerian_forest_fires_dataset_UPDATE.csv", skip = 1) |> 
  janitor::clean_names()
Warning: One or more parsing issues, call `problems()` on your data frame for details,
e.g.:
  dat <- vroom(...)
  problems(dat)
Rows: 246 Columns: 14
── Column specification ────────────────────────────────────────────────────────
Delimiter: ","
chr (14): day, month, year, Temperature, RH, Ws, Rain, FFMC, DMC, DC, ISI, B...

ℹ Use `spec()` to retrieve the full column specification for this data.
ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

Data Understanding

After importing the data, I need to investigate if the data is imported as expected, and confirm that all data types are as expected.

Data Preview

A quick preview of the data is the first step:

Show the code 
algeria_ff |> 
  head() |> 
  kable()
algeria_ff |> 
  tail() |> 
  kable()
algeria_ff |> 
  car::some() |> 
  kable()
Table 1: Data preview
(a)
day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
01 06 2012 29 57 18 0 65.7 3.4 7.6 1.3 3.4 0.5 not fire
02 06 2012 29 61 13 1.3 64.4 4.1 7.6 1 3.9 0.4 not fire
03 06 2012 26 82 22 13.1 47.1 2.5 7.1 0.3 2.7 0.1 not fire
04 06 2012 25 89 13 2.5 28.6 1.3 6.9 0 1.7 0 not fire
05 06 2012 27 77 16 0 64.8 3 14.2 1.2 3.9 0.5 not fire
06 06 2012 31 67 14 0 82.6 5.8 22.2 3.1 7 2.5 fire
(b)
day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
25 09 2012 28 70 15 0 79.9 13.8 36.1 2.4 14.1 3 not fire
26 09 2012 30 65 14 0 85.4 16 44.5 4.5 16.9 6.5 fire
27 09 2012 28 87 15 4.4 41.1 6.5 8 0.1 6.2 0 not fire
28 09 2012 27 87 29 0.5 45.9 3.5 7.9 0.4 3.4 0.2 not fire
29 09 2012 24 54 18 0.1 79.7 4.3 15.2 1.7 5.1 0.7 not fire
30 09 2012 24 64 15 0.2 67.3 3.8 16.5 1.2 4.8 0.5 not fire
(c)
day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
04 06 2012 25 89 13 2.5 28.6 1.3 6.9 0 1.7 0 not fire
10 07 2012 33 69 13 0.7 66.6 6 9.3 1.1 5.8 0.5 not fire
16 07 2012 28 76 21 0 72.6 7 25.5 0.7 8.3 0.4 not fire
21 07 2012 33 70 17 0 85.4 18.5 71.5 5.2 22.4 8.8 fire
30 08 2012 35 70 17 0.8 72.7 25.2 180.4 1.7 37.4 4.2 not fire
23 06 2012 33 59 16 0.8 74.2 7 8.3 1.6 6.7 0.8 not fire
13 08 2012 35 34 16 0.2 88.3 16.9 45.1 7.5 17.5 10.5 fire
14 08 2012 37 40 13 0 91.9 22.3 55.5 10.8 22.3 15.7 fire
11 09 2012 30 73 14 0 79.2 6.5 16.6 2.1 6.6 1.2 not fire
15 09 2012 32 51 13 0 88.7 16 50.2 6.9 17.8 9.8 fire

Table 1 shows the first six observations, Table 1 (a), the last six observations, Table 1 (b), and 10 random observations from the data, Table 1 (c).

From Table 2, all the variables are character when they should be majorly numeric and one or two categorical variable. I can also see that the regions are not indicated in the data. The variables present are day, month, year, temperature, rh, ws, rain, ffmc, dmc, dc, isi, bui, fwi, classes.

Show the code 
skimr::skim(algeria_ff)
Table 2: Data Properties
(a)
Name algeria_ff
Number of rows 246
Number of columns 14
_______________________
Column type frequency:
character 14
________________________
Group variables None

Variable type: character

(b)
skim_variable n_missing complete_rate min max empty n_unique whitespace
day 0 1.00 2 29 0 33 0
month 1 1.00 2 5 0 5 0
year 1 1.00 4 4 0 2 0
temperature 1 1.00 2 11 0 20 0
rh 1 1.00 2 2 0 63 0
ws 1 1.00 1 2 0 19 0
rain 1 1.00 1 4 0 40 0
ffmc 1 1.00 2 4 0 174 0
dmc 1 1.00 1 4 0 167 0
dc 1 1.00 1 6 0 199 0
isi 1 1.00 1 4 0 107 0
bui 1 1.00 1 4 0 175 0
fwi 1 1.00 1 4 0 127 0
classes 2 0.99 4 8 0 3 0

Missing Data

There’s a maximum of two missing data, which is in the classes variable, Table 2 (b). I will investigate this:

Show the code 
algeria_ff |> 
  filter(is.na(classes)) |>  kable()
Table 3: Missing data
day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
Sidi-Bel Abbes Region Dataset NA NA NA NA NA NA NA NA NA NA NA NA NA
14 07 2012 37 37 18 0.2 88.9 12.9 14.6 9 12.5 10.4 fire NA

There’s an interesting finding in Table 3. The start of Sidi-Bel Abbes region dataset can be seen under the day variable. I will add row numbers and a new column called region and add each region according to the row number where Sidi-Bel Abbes appears in the variable day. All data before Sidi-Bel Abbes are Bejaia region data,

Show the code 
algeria_ff <- algeria_ff |> 
  mutate(
    id = row_number(),
    .before = day
  )
head(algeria_ff) |> kable()
Table 4: Row numbers added
id day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
1 01 06 2012 29 57 18 0 65.7 3.4 7.6 1.3 3.4 0.5 not fire
2 02 06 2012 29 61 13 1.3 64.4 4.1 7.6 1 3.9 0.4 not fire
3 03 06 2012 26 82 22 13.1 47.1 2.5 7.1 0.3 2.7 0.1 not fire
4 04 06 2012 25 89 13 2.5 28.6 1.3 6.9 0 1.7 0 not fire
5 05 06 2012 27 77 16 0 64.8 3 14.2 1.2 3.9 0.5 not fire
6 06 06 2012 31 67 14 0 82.6 5.8 22.2 3.1 7 2.5 fire

I will perform the previous filter operation in Table 3 to get the start of the row number for Sidi-Bel Abbes Region.

Show the code 
algeria_ff |> 
  filter(is.na(classes))
Table 5 
# A tibble: 2 × 15
     id day    month year  temperature rh    ws    rain  ffmc  dmc   dc    isi  
  <int> <chr>  <chr> <chr> <chr>       <chr> <chr> <chr> <chr> <chr> <chr> <chr>
1   123 Sidi-… <NA>  <NA>  <NA>        <NA>  <NA>  <NA>  <NA>  <NA>  <NA>  <NA> 
2   168 14     07    2012  37          37    18    0.2   88.9  12.9  14.6… 12.5 
# ℹ 3 more variables: bui <chr>, fwi <chr>, classes <chr>

Sidi-Bel Abbes data starts from 124, Table 5. I will add the regions and remove the id variable that contains the row numbers. The number of observations for each region can be seen in Table 6

Show the code 
algerian_ff <- algeria_ff |> 
  mutate(
    region = case_when(id <= 122 ~ "Bejaia",
                       .default = "Sidi-Bel Abbes"),
    .before = day,
    .keep = "unused"
  )

head(algerian_ff)
Table 6: Number of observations for the regions 
# A tibble: 6 × 15
  region day   month year  temperature rh    ws    rain  ffmc  dmc   dc    isi  
  <chr>  <chr> <chr> <chr> <chr>       <chr> <chr> <chr> <chr> <chr> <chr> <chr>
1 Bejaia 01    06    2012  29          57    18    0     65.7  3.4   7.6   1.3  
2 Bejaia 02    06    2012  29          61    13    1.3   64.4  4.1   7.6   1    
3 Bejaia 03    06    2012  26          82    22    13.1  47.1  2.5   7.1   0.3  
4 Bejaia 04    06    2012  25          89    13    2.5   28.6  1.3   6.9   0    
5 Bejaia 05    06    2012  27          77    16    0     64.8  3     14.2  1.2  
6 Bejaia 06    06    2012  31          67    14    0     82.6  5.8   22.2  3.1  
# ℹ 3 more variables: bui <chr>, fwi <chr>, classes <chr>

Now we can check for missing data again

Show the code 
algerian_ff |> 
  filter(if_any(everything(), is.na)) |> 
  kable()
region day month year temperature rh ws rain ffmc dmc dc isi bui fwi classes
Sidi-Bel Abbes Sidi-Bel Abbes Region Dataset NA NA NA NA NA NA NA NA NA NA NA NA NA
Sidi-Bel Abbes 14 07 2012 37 37 18 0.2 88.9 12.9 14.6 9 12.5 10.4 fire NA

The missing points are still the same. Here, I will remove this data points and proceed with the analysis.

Show the code 
algerian_ff <- algerian_ff |> 
  drop_na() |> 
  filter(classes %in% c("not fire", "fire"))

I also need to change the other variables to numeric data types except region and classes which will be changed to factor variable type.

Show the code 
algerian_ff <- algerian_ff |> 
  mutate(
    region = factor(region),
    classes = ifelse(classes == "not fire", 0, 1),
    classes = factor(classes, labels = c("not fire", "fire"), levels = c(0 ,1)),
    across(where(is.character), parse_number)
  )

str(algerian_ff)
tibble [243 × 15] (S3: tbl_df/tbl/data.frame)
 $ region     : Factor w/ 2 levels "Bejaia","Sidi-Bel Abbes": 1 1 1 1 1 1 1 1 1 1 ...
 $ day        : num [1:243] 1 2 3 4 5 6 7 8 9 10 ...
 $ month      : num [1:243] 6 6 6 6 6 6 6 6 6 6 ...
 $ year       : num [1:243] 2012 2012 2012 2012 2012 ...
 $ temperature: num [1:243] 29 29 26 25 27 31 33 30 25 28 ...
 $ rh         : num [1:243] 57 61 82 89 77 67 54 73 88 79 ...
 $ ws         : num [1:243] 18 13 22 13 16 14 13 15 13 12 ...
 $ rain       : num [1:243] 0 1.3 13.1 2.5 0 0 0 0 0.2 0 ...
 $ ffmc       : num [1:243] 65.7 64.4 47.1 28.6 64.8 82.6 88.2 86.6 52.9 73.2 ...
 $ dmc        : num [1:243] 3.4 4.1 2.5 1.3 3 5.8 9.9 12.1 7.9 9.5 ...
 $ dc         : num [1:243] 7.6 7.6 7.1 6.9 14.2 22.2 30.5 38.3 38.8 46.3 ...
 $ isi        : num [1:243] 1.3 1 0.3 0 1.2 3.1 6.4 5.6 0.4 1.3 ...
 $ bui        : num [1:243] 3.4 3.9 2.7 1.7 3.9 7 10.9 13.5 10.5 12.6 ...
 $ fwi        : num [1:243] 0.5 0.4 0.1 0 0.5 2.5 7.2 7.1 0.3 0.9 ...
 $ classes    : Factor w/ 2 levels "not fire","fire": 1 1 1 1 1 2 2 2 1 1 ...

Exploratory Data Analyis

Let’s do some exploratory data analysis to understand our target variable, predictors, and the relationship between them. ## Target Variable

Show the code 
algerian_ff |>
  count(classes) |> 
  ggplot(aes(classes, n, fill = classes)) +
  geom_bar(stat = "identity") +
  geom_text(
    aes(label = n),
    nudge_y = 11.5,
    size = 4,
    col = "#ff3000"
  ) +
  scale_fill_colorblind() +
  labs(
    x = "Classes",
    y = "Count",
    title = "Frequency of Fire Occurrence Situation"
  ) +
  coord_cartesian(ylim = c(0, 145)) +
  scale_y_continuous(breaks = seq(0, 145, 29)) +
  theme(
    legend.position = "none",
    plot.title = element_text(hjust = .5)
  )
Figure 1: Frequency of Classes

Figure 1 shows there are more occurrence of fire than not fire.

Features / Predictors

Show the code 
algerian_ff |> 
  select(-classes) |> 
  GGally::ggpairs(
    title = "Predictors"
  ) +
  theme_bw()
Figure 2: Predictors plots

As show in Figure 2, rain, ws, dmc, dc, isi, bui and fwi are rightly skewed, temperature and rh are normally distributed, while ffmc is left-skewed. There’s also high correlation between some of the variables.

Target vs Feature

Show the code 
algerian_ff |> 
  summarize(
    .by = c(classes, region),
    count = n()
  ) |> 
  ggplot(aes(region, count, fill = fct_reorder(classes, count))) +
  geom_col(position = "dodge") +
  geom_text(
    aes(label = count),
    size = 3.2,
    vjust = -.2,
    position = position_dodge(width = 1)
    # position = position_nudge(x = 0, y =1)
  ) +
  scale_fill_calc() +
  labs(
    fill = "Region",
    x = "Classes",
    y = "Count",
    title = "Frequency of Fire Occurrence Situation Across Regions",
    subtitle = "There's more fire outbreak in Sidi-Bel Abbes than in Bejaia"
  )
Figure 3: There are more fire outbreak in Sidi-Bel Abbes than in Bejaia
Show the code 
algerian_ff |> 
  ggplot(aes(rain, temperature, col = classes)) +
  geom_jitter() +
  scale_color_wsj() +
  labs(
    x = "Rain",
    y = "Temperature",
    title = "Temperature vs Rain relationship for Fire Occurrence",
    subtitle = "Fire rarely occur on days with high rainfall"
  ) +
  theme(plot.subtitle = element_text(size = 10))

Show the code 
algerian_ff |> 
  ggplot(aes(day, rh, colour = classes)) +
  geom_point() +
  labs(
    x = "Day",
    y = "Relative Humidity (%)",
    title = "Fire occurence for each days in a month given the day's humidity"
  ) +
  facet_wrap(~month)

algerian_ff |> 
  ggplot(aes(day, rh, colour = classes)) +
  geom_point() +
  labs(
    x = "Day",
    y = "Relative Humidity (%)",
    title = "Fire occurence for each days in a month for a region given the day's humidity"
  ) +
  facet_grid(region~month)
(a)
(b)
Figure 4: Relative humidity of each days across the months showing the occurrence of fire.

Figure 4 (a) shows no clear pattern in fire occurrence, but it is visible that the 8th month had more fire occurring from its 10th day to the 27th day. Fire occurred more in days with low relative humidity compared to those with high humidity. Figure 4 (b) shows how month 8 had fire occuring the most, even at high relative humidity.

Modeling

As introduced earlier, the model algorithm I will be using for this binary classification is logistic regression. The modeling worklow will go as thus:

  • Data sharing
  • Create resamples
  • Create model specification
  • Feature engineering
  • Workflow and model training
  • Model evaluation
  • Model last fit on whole data.

Data Sharing

Let’s split the data into two portions. The training data will be 70% of the whole data while the test data will be 30%.

Show the code 
set.seed(123)
algerian_split <- initial_split(algerian_ff, prop = .7)
algerian_train <- training(algerian_split)
algerian_test <- testing(algerian_split)
algerian_train |> 
  count(region, classes)
Table 7: Distribution of the targer variable across regions 
# A tibble: 4 × 3
  region         classes      n
  <fct>          <fct>    <int>
1 Bejaia         not fire    41
2 Bejaia         fire        48
3 Sidi-Bel Abbes not fire    32
4 Sidi-Bel Abbes fire        49

Table 7 shows how the data is distributed in the training data.

Model Specification

Next we create the model specification

Show the code 
lr_spec <- logistic_reg() |> 
  set_mode("classification") |> 
  set_engine("glm")

lr_spec |> 
  translate()
Logistic Regression Model Specification (classification)

Computational engine: glm 

Model fit template:
stats::glm(formula = missing_arg(), data = missing_arg(), weights = missing_arg(), 
    family = stats::binomial)

Feature Engineering

For feature engineering, we will remove zero and near-zero variance variables. After, we’ll apply Yeo-Johnson to prevent to handle data values that have zero or negative values. After this, we standardize the results and make all factor variables one-hot coded.

Show the code 
lr_rec <- recipe(
  classes ~ . + 1, data = algerian_train
) |> 
  step_zv(all_numeric_predictors()) |> 
  step_nzv(all_numeric_predictors()) |> 
  step_YeoJohnson(all_numeric_predictors()) |> 
  step_scale(all_numeric_predictors()) |> 
  step_pca(all_numeric_predictors()) |> 
  step_dummy(region)
  
lr_rec
── Recipe ──────────────────────────────────────────────────────────────────────
── Inputs 
Number of variables by role
outcome:    1
predictor: 14
── Operations 
• Zero variance filter on: all_numeric_predictors()
• Sparse, unbalanced variable filter on: all_numeric_predictors()
• Yeo-Johnson transformation on: all_numeric_predictors()
• Scaling for: all_numeric_predictors()
• PCA extraction with: all_numeric_predictors()
• Dummy variables from: region

To see how the data looks after preprocessing let’s use the prep() and juice() function.

Show the code 
lr_rec |> 
  prep() |> 
  juice() |> 
  head() |> 
  kable()
Table 8: Preprocessed data
classes PC1 PC2 PC3 PC4 PC5 region_Sidi.Bel.Abbes
fire -12.75870 1.065189 1.9127196 0.1717558 1.5907799 1
fire -15.82715 3.592703 -0.6338943 -0.1082043 0.1228698 1
fire -13.60741 1.357303 -0.8886342 -0.0618020 0.1017522 1
not fire -11.74371 -3.347725 -1.0163208 1.2834374 1.1943557 0
fire -13.83764 1.683620 1.3037796 0.2674702 0.5054699 1
fire -14.13147 1.995548 -0.6331457 0.3294726 0.1962187 1

From Table 8 we can see that the variable year has been removed.The variables has also been reduced as some of them were related, check Figure 2 ## Workflow

Show the code 
lr_wf <- workflow() |> 
  add_model(lr_spec) |> 
  add_recipe(lr_rec) |> 
  fit(algerian_train)

Model Result

Show the code 
lr_wf |> tidy()
Table 9: Model summary 
# A tibble: 7 × 5
  term                  estimate std.error statistic   p.value
  <chr>                    <dbl>     <dbl>     <dbl>     <dbl>
1 (Intercept)             -8.40      7.01     -1.20  0.230    
2 PC1                     -0.758     0.538    -1.41  0.159    
3 PC2                      3.43      0.847     4.05  0.0000517
4 PC3                      0.480     0.459     1.05  0.296    
5 PC4                      1.77      0.638     2.77  0.00558  
6 PC5                     -0.999     0.440    -2.27  0.0231   
7 region_Sidi.Bel.Abbes    0.356     0.959     0.371 0.711

When all the factors are zero, the odds of fire occurring is very low, i.e. the exponential of the intercept estimate, 2.2380029^{-4}. For region Sidi-Bel Abbes, the odds of a fire outbreak is 1.5 times higher, Table 9.

Model Evaluation

Accuracy

Show the code 
lr_wf |> augment(algerian_test) |> 
  accuracy(classes, .pred_class)
# A tibble: 1 × 3
  .metric  .estimator .estimate
  <chr>    <chr>          <dbl>
1 accuracy binary         0.918

The accuracy of the model is high at 92%.

Sensitivity

Show the code 
lr_wf |> 
  augment(algerian_test) |> 
  sensitivity(classes, .pred_class)
# A tibble: 1 × 3
  .metric     .estimator .estimate
  <chr>       <chr>          <dbl>
1 sensitivity binary         0.818

The model is 82% sensitive.

Precision

Show the code 
lr_wf |> 
  augment(algerian_test) |> 
  precision(classes, .pred_class)
# A tibble: 1 × 3
  .metric   .estimator .estimate
  <chr>     <chr>          <dbl>
1 precision binary             1

ROC-AUC

Show the code 
lr_wf |> 
  augment(algerian_test) |> 
  roc_auc(classes, `.pred_not fire`)
# A tibble: 1 × 3
  .metric .estimator .estimate
  <chr>   <chr>          <dbl>
1 roc_auc binary         0.992
Show the code 
lr_wf |> 
  augment(algerian_test) |> 
  roc_curve(classes, `.pred_not fire`) |> 
  autoplot()
Figure 5: Area under the curve is high

The area under the curve is .99 which is very good Figure 5.

Confusion Matrix

Show the code 
lr_wf |> 
  augment(algerian_test) |> 
  conf_mat(classes, .pred_class) 
          Truth
Prediction not fire fire
  not fire       27    0
  fire            6   40

The model performance precision and accuracy is high above 90%, with precision at 100%. There are 6 false positives which signals the likelihood of fire when there is supposed to be non.

Summary and Conclusion

The project seek to predict the likelihood of fire outbreak in two regions of Algeria. A logistic regression model was employed with 6 preprocessing steps. The model developed was evaluated and has high accuracy at 92%, a high precision of 100%, 0.99 for roc_auc

References

Abid, Faroudja, and Nouma Izeboudjen. 2020. “Predicting Forest Fire in Algeria Using Data Mining Techniques: Case Study of the Decision Tree Algorithm.” In, 363–70. Springer International Publishing. https://doi.org/10.1007/978-3-030-36674-2_37.