统计列表中每个元素出现的次数

例如统计基因个数等

输入	A A A B B C
输出

如何引用？

建议直接写网址。4600+篇google学术，3900+篇知网学术
正式引用：Tang D, Chen M, Huang X, Zhang G, Zeng L, Zhang G, Wu S, Wang Y.SRplot: A free online platform for data visualization and graphing. PLoS One. 2023 Nov 9;18(11):e0294236. doi: 10.1371/journal.pone.0294236. PMID: 37943830.
方法章节：Heatmap was plotted by https://www.bioinformatics.com.cn (last accessed on 10 Dec 2024), an online platform for data analysis and visualization.
致谢章节：We thank Mingjie Chen (Shanghai NewCore Biotechnology Co., Ltd.) for providing data analysis and visualization support.