FASTQ读段质量过滤
按全碱基闭区间筛选严格四行单端PHRED+33 FASTQ，保留选中完整记录的原字节，并导出所有保留或删除理由。
- 1添加输入
- 2调整设置
- 3获取结果
工具输入和文件在当前浏览器处理，不会上传。
开始之前
用明确质量区间筛选整条读段。默认30–42对应?到K的质量字符；质量行里的@和+仍是分值数据。
如何使用
- 打开四行PHRED+33 FASTQ，设置包含端点的质量区间。
- 核对保留/删除计数、直方图和每条完整理由。
- 下载保留原字节的过滤FASTQ与所有决策记录。
支持范围与限制
一个UTF-8文件或粘贴文本，最多10 MiB、100,000条记录、总计4,000,000个碱基；完整下载合计最多40 MiB。整份空文件输出零条，非空记录必须至少有一个碱基。
严格四行：非空@标识符、IUPAC DNA/RNA序列、+及可选完全相同的完整标识符、等长质量行。PHRED+33的ASCII !到~表示0–93；不支持折行FASTQ、猜测Phred64或双端同步。
每个碱基都须在闭区间内，默认30–42，出现Q43也会删除整条。报告包含最低/最高/均值、区间外碱基数、保留或删除理由，以及两份完整94格直方图。均值是质量分值算术平均。
同文件只能全部LF或全部CRLF；混用及单独CR拒绝。最后质量行可无末尾换行。保留整条记录的header、plus行、原字节、顺序与EOF状态；字节跨度为UTF-8左闭右开偏移。
表格预览前200条，长单元格裁到2,000字符。报告超过20,000字符时复制明确为预览；完整FASTQ/JSON/CSV在下载中。非法或超限不交付部分过滤文件，不作生物学或医疗解释。
操作示例
示例输入
@first info ACGT + ???? @lower AC +lower @+ @upper A + L
示例参数
{"secondary":"","params":{"minPhred":30,"maxPhred":42,"spreadsheetSafe":true}}示例输出
{"format":"strict-four-line-single-end-PHRED33","summary":{"records":3,"kept":1,"dropped":2,"bases":7,"minPhred":30,"maxPhred":42,"newline":"CRLF","histogramBins":94,"keptBytes":28},"histogram":[0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"retainedHistogram":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"records":[{"index":0,"id":"first info","byteStart":0,"byteEnd":28,"bases":4,"minimum":30,"maximum":30,"mean":30,"outside":0,"decision":"kept","reason":"all_bases_in_interval"},{"index":1,"id":"lower","byteStart":28,"byteEnd":52,"bases":2,"minimum":10,"maximum":31,"mean":20.5,"outside":1,"decision":"dropped","reason":"quality_outside_interval"},{"index":2,"id":"upper","byteStart":52,"byteEnd":69,"bases":1,"minimum":43,"maximum":43,"mean":43,"outside":1,"decision":"dropped","reason":"quality_outside_interval"}],"scope":"Inclusive all-base interval. Wrapped FASTQ, Phred64, paired synchronization and zero-base records unsupported. Source byte spans use half-open UTF8 offsets; kept records retain bytes and EOF exactly. Mean is the arithmetic score average."}出现问题时
检查四行结构、plus可选标识符完全匹配、非空IUPAC序列、ASCII PHRED+33质量和统一换行；修正区间或重导出支持的文件。完整产物超过40 MiB时缩小输入重跑。
常见问题
质量行以@开头为何不是下一条？
记录按明确四行结构划分；@是合法PHRED+33分值31，质量行中的+是分值10。
只设最低30能等价默认规则吗？
不能。默认是30–42闭区间，每个碱基都须满足两个边界，分值43也失败。
会同步保留双端配对吗？
不会。本工具独立处理单端文件；配对数据请使用专门的配对流程。