Code generation method, code generating apparatus and computer readable storage medium

A code is generated for mapping source to target code words which allows encoding source data at reduced probability of incorrect decoding, e.g. for DNA storage. The target code words are grouped (102) into subsets and comprise identifying and remaining portions. The identifying portions of target code words corresponding to a same subset are identical. A first code symbol set of source code words is selected (103) for addressing the subsets. For the subsets, neighboring subsets are determined (104). The identifying portions of the target code words of neighboring subsets differ from those of the corresponding subset by up to a predetermined amount of symbols. Source code words are assigned (105) where the corresponding first code symbols address the same subset to said subset such that an amount of target code words of said subset having their remaining portions identical to their neighboring subsets corresponds to an optimization criterion.