A method for producing a peptide library comprising diverse protein structures, said method comprising: (i) obtaining a plurality of amino acid sequences of diverse protein structures from bioinformatic source data and identifying fragments of proteins that are computationally predicted to independently form secondary structures and/or assemblies of secondary structures and/or folds when isolated from the flanking sequences in the protein of origin as determined by three criteria of compactness, non-polar buried surface area, and degree of independence according to the scoring function: Score Z H I = Z 1 avg - Z / Z 1 Dev + H - H 1 avg / H 1 Dev + I 1 avg - I / I 1 Dev + Z 2 avg - Z / Z 2 Dev + H - H 2 avg / H 2 Dev + I 2 avg - I / I 2 Dev wherein: Z, H, and I are respectively compactness, hydrophobicity, degree of isolatedness of a fragment, wherein: Z is the solvent-accessible surface area of the fragment divided by a minimum surface area of the fragment being the surface area of a sphere having an equal volume to the fragment; H is a fraction of buried nonpolar area in total nonpolar area; I is a fraction of non-polar solvent accessible surface area that was originally buried in the interior of a protein but is exposed to solvent after cutting in the total solvent accessible surface area of the fragment; avg denotes an arithmetic average of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; and Dev denotes a standard deviation of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; (ii) producing peptides having the amino acid sequences obtained at (i); and (iii) displaying the peptides at (ii) such that said peptides form secondary structures and/or assemblies of secondary structures and/or folds. (i) obtaining a plurality of amino acid sequences of diverse protein structures from bioinformatic source data and identifying fragments of proteins that are computationally predicted to independently form secondary structures and/or assemblies of secondary structures and/or folds when isolated from the flanking sequences in the protein of origin as determined by three criteria of compactness, non-polar buried surface area, and degree of independence according to the scoring function: Score Z H I = Z 1 avg - Z / Z 1 Dev + H - H 1 avg / H 1 Dev + I 1 avg - I / I 1 Dev + Z 2 avg - Z / Z 2 Dev + H - H 2 avg / H 2 Dev + I 2 avg - I / I 2 Dev wherein: Z, H, and I are respectively compactness, hydrophobicity, degree of isolatedness of a fragment, wherein: Z is the solvent-accessible surface area of the fragment divided by a minimum surface area of the fragment being the surface area of a sphere having an equal volume to the fragment; H is a fraction of buried nonpolar area in total nonpolar area; I is a fraction of non-polar solvent accessible surface area that was originally buried in the interior of a protein but is exposed to solvent after cutting in the total solvent accessible surface area of the fragment; avg denotes an arithmetic average of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; and Dev denotes a standard deviation of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; Z, H, and I are respectively compactness, hydrophobicity, degree of isolatedness of a fragment, wherein: Z is the solvent-accessible surface area of the fragment divided by a minimum surface area of the fragment being the surface area of a sphere having an equal volume to the fragment; H is a fraction of buried nonpolar area in total nonpolar area; I is a fraction of non-polar solvent accessible surface area that was originally buried in the interior of a protein but is exposed to solvent after cutting in the total solvent accessible surface area of the fragment; Z is the solvent-accessible surface area of the fragment divided by a minimum surface area of the fragment being the surface area of a sphere having an equal volume to the fragment; H is a fraction of buried nonpolar area in total nonpolar area; I is a fraction of non-polar solvent accessible surface area that was originally buried in the interior of a protein but is exposed to solvent after cutting in the total solvent accessible surface area of the fragment; avg denotes an arithmetic average of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; and Dev denotes a standard deviation of Z 1, H 1, I 1, Z 2, H 2 and I 2, wherein superscript 1 defines Z, H, I calculated with respect to fragment size and wherein superscript 2 defines Z, H, I calculated as a function of the fraction of the fragment size to the whole protein; (ii) producing peptides having the amino acid sequences obtained at (i); and (iii) displaying the peptides at (ii) such that said peptides form secondary structures and/or assemblies of secondary structures and/or folds.