4. Evaluation methods
Many evaluation methods for urban water bodies and green spaces are available, including AHP, principal component analysis (PCA), fuzzy comprehensive evaluation method (FCED), cluster analysis (CA), etc. Each method has its own advantages and disadvantages and is suitable for different evaluation objectives. According to the complexity of evaluation calculation and evaluation objects, evaluation methods can be divided into general evaluation methods and comprehensive evaluation methods. General evaluation methods include AHP and PCA. Comprehensive evaluation methods are obtained introducing the membership degree of fuzzy mathematics and the grayscale concept of gray system theory and include FCED and CA.