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Python for Data Science: Identifying Email Threats

Preliminary AnalysisPreliminary Analysis

Checking for null values and duplicates is important in the data cleaning and preparation process because this help to ensure the quality and accuracy of the data.

  • Null values can indicate missing or incomplete data and, if not handled properly, can lead to inaccuracies in any analysis or modeling performed on the data. For example, if a null value is present in a column that is used as a predictor variable in a machine learning model, the model will not be able to predict that data point;
  • Duplicates can also lead to inaccuracies in analysis, especially if they are not identified and removed. For example, if a data point is duplicated, it will be counted twice in any analysis performed, potentially skewing the results. Additionally, duplicate data can also increase the size of the dataset and slow down any analysis or modeling performed on it.


  1. See if there are any NaNs (Not a Number);
  2. Drop duplicates since they are not useful for our analysis.

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Section 1. Chapter 4