# Why do all Machine Learning models follow the same steps?

## Understand how all Machine Learning Models follow the same procedure over and over again

## Introduction

It's tough to find things that always work the same way in programming.

The steps of a Machine Learning (ML) model can be an exception.

Each time we want to compute a model *(mathematical equation)* and make predictions with it, we would always make the following steps:

`model.fit()`

→ to**compute the numbers**of the mathematical equation..`model.predict()`

→ to**calculate predictions**through the mathematical equation.`model.score()`

→ to measure**how good the model's predictions are**.

And I am going to show you this with 3 different ML models.

`DecisionTreeClassifier()`

`RandomForestClassifier()`

`LogisticRegression()`

## Load the Data

But first, let's load a dataset from CIS executing the lines of code below:

- The goal of this dataset is
- To predict
`internet_usage`

ofpeople(rows)- Based on their
socio-demographical characteristics(columns)

```
import pandas as pd
df = pd.read_csv('https://raw.githubusercontent.com/jsulopz/data/main/internet_usage_spain.csv')
df.head()
```

internet_usage | sex | age | education | |
---|---|---|---|---|

0 | 0 | Female | 66 | Elementary |

1 | 1 | Male | 72 | Elementary |

2 | 1 | Male | 48 | University |

3 | 0 | Male | 59 | PhD |

4 | 1 | Female | 44 | PhD |

## Data Preprocessing

We need to transform the categorical variables to **dummy variables** before computing the models:

```
df = pd.get_dummies(df, drop_first=True)
df.head()
```

## Feature Selection

Now we separate the variables on their respective role within the model:

```
target = df.internet_usage
explanatory = df.drop(columns='internet_usage')
```

## ML Models

### Decision Tree Classifier

```
from sklearn.tree import DecisionTreeClassifier
model = DecisionTreeClassifier()
model.fit(X=explanatory, y=target)
pred_dt = model.predict(X=explanatory)
accuracy_dt = model.score(X=explanatory, y=target)
```

### Support Vector Machines

```
from sklearn.svm import SVC
model = SVC()
model.fit(X=explanatory, y=target)
pred_sv = model.predict(X=explanatory)
accuracy_sv = model.score(X=explanatory, y=target)
```

### K Nearest Neighbour

```
from sklearn.neighbors import KNeighborsClassifier
model = KNeighborsClassifier()
model.fit(X=explanatory, y=target)
pred_kn = model.predict(X=explanatory)
accuracy_kn = model.score(X=explanatory, y=target)
```

The only thing that changes are the results of the prediction. The models are different. But they all follow the **same steps** that we described at the beginning:

`model.fit()`

→ to compute the mathematical formula of the model`model.predict()`

→ to calculate predictions through the mathematical formula`model.score()`

→ to get the success ratio of the model

## Comparing Predictions

You may observe in the following table how the *different models make different predictions*, which often doesn't coincide with reality (misclassification).

For example, `model_svm`

doesn't correctly predict the row 214; as if this person *used internet* `pred_svm=1`

, but they didn't: `internet_usage`

for 214 in reality is 0.

```
df_pred = pd.DataFrame({'internet_usage': df.internet_usage,
'pred_dt': pred_dt,
'pred_svm': pred_sv,
'pred_lr': pred_kn})
df_pred.sample(10, random_state=7)
```

internet_usage | pred_dt | pred_svm | pred_lr | |
---|---|---|---|---|

214 | 0 | 0 | 1 | 0 |

2142 | 1 | 1 | 1 | 1 |

1680 | 1 | 0 | 0 | 0 |

1522 | 1 | 1 | 1 | 1 |

325 | 1 | 1 | 1 | 1 |

2283 | 1 | 1 | 1 | 1 |

1263 | 0 | 0 | 0 | 0 |

993 | 0 | 0 | 0 | 0 |

26 | 1 | 1 | 1 | 1 |

2190 | 0 | 0 | 0 | 0 |

## Choose Best Model

Then, we could choose the model with a **higher number of successes** on predicting the reality.

```
df_accuracy = pd.DataFrame({'accuracy': [accuracy_dt, accuracy_sv, accuracy_kn]},
index = ['DecisionTreeClassifier()', 'SVC()', 'KNeighborsClassifier()'])
df_accuracy
```

accuracy | |
---|---|

DecisionTreeClassifier() | 0.859878 |

SVC() | 0.783707 |

KNeighborsClassifier() | 0.827291 |

Which is the best model here?

- Let me know in the comments below ↓

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