PDF 转 CSV
把 PDF 里的表格取出来，存为逗号分隔的文件。
这款工具完全在你的浏览器中运行。文件从不上传，你可以在浏览器的网络标签中亲自验证这一点。 亲自验证：打开浏览器的网络标签观察。你会看到一个查询你是否还有剩余任务的小请求，只包含工具名称和一段哈希，绝不会包含文件。
这款工具的作用
A PDF has no idea what a table is. There are no cells and no rows in the file, only text placed at coordinates that happen to line up, so recovering a table means finding the columns again. This tool clusters the horizontal positions of every text run, looks for a stretch of lines whose runs all fall into the same bands, and writes what it finds as CSV. Because it is inference rather than reading, every table comes with a confidence score, and the threshold is yours to set.
The usual case is numbers you would otherwise retype: a bank statement that only arrives as a PDF, invoice lines that have to be reconciled, a price list from a supplier, or an export from a system that offers PDF and nothing else.
工作原理
- Drop the PDF onto this page. If it is a scan with no text layer, you are sent to OCR PDF rather than given an empty spreadsheet.
- Pick the delimiter. Comma is standard; semicolon is what Excel expects in most of Europe; tab suits pasting straight into a sheet.
- Set the confidence threshold. 55 per cent is the default; lower it to catch loosely aligned tables, raise it if prose is being mistaken for one.
- Choose one file per table, or a single file with the tables one after another.
- Press Extract tables. Each output shows its page and its confidence, so a doubtful table is visible as doubtful before you use it.
The detail that separates a table detector that works from one that does not is right alignment. Number columns are set flush right, so their runs share an end position rather than a start position, and a detector that clusters only on where text begins misses every financial table - which is most of what anybody converts. Both edges are clustered here.
Nothing is returned below the confidence threshold, and that is a deliberate refusal rather than a gap. A spreadsheet full of misaligned fragments looks like a result and is worse than no result, because someone will use it.
The threshold is a real dial. At 30 per cent almost any run of aligned lines is offered, which is useful for a loosely typeset table you already know is there. At 90 per cent only tables with clean, consistent columns survive, which is what you want when converting a hundred pages unattended. The default of 55 is where a typical report's tables come through and its paragraphs do not.
Detection and writing both happen in your browser. The numbers in a bank statement are about as sensitive as a document gets, and none of them are transmitted: the PDF is read and the CSV written without any part of either reaching a network.
这款工具做不到的事
- Ruling lines are ignored. Columns are found from where the text sits, so a heavily bordered table whose text does not line up is still missed, and a table with no borders at all converts fine as long as it is aligned.
- Merged and spanning cells flatten. A cell spanning three columns is written into one of them and the rest are left empty, because CSV has no way to say that a cell covers more than one column.
- A scanned table has no text to cluster, so nothing is found. Run OCR PDF first to add a text layer, then come back.
常见问题
- 它是怎么找到表格的？
- 靠几何位置。表格表现为一连串相邻的行，其文字落在相同的竖直带里。每一行的左右两端都会被聚类，因为数字列是右对齐的，否则检测器根本看不见它们。每个候选都会得到一个置信度分数，低于你阈值的一律丢弃，而不是硬猜。
- 明明有一张表却被漏掉了。现在怎么办？
- 调低置信度阈值——40% 能拾起大多数默认会拒绝的、对齐较松的表格。如果还是没用，那张表的文字很可能根本没有对齐成列，这在单元格大量换行时会发生；PDF 转文字至少能把内容交给你手动处理。
- 我该选哪种分隔符？
- 如果文件不是要进欧洲版 Excel，就用逗号。如果你所在地区的数字用逗号作小数点，就用分号，因为这时 Excel 读分号分隔的文件，反而会把逗号分隔的弄乱。若要直接粘进已打开的电子表格，制表符最保险。
- 它能从扫描页里读出表格吗？
- 单靠它不行。扫描件是图像，没有可供聚类的文字位置。先运行 OCR 文字识别，表格就变得可检测了——不过数字上的 OCR 准确度值得逐格核对后再采信。
- 文件会被上传到什么地方吗？
- 不会。PDF 的读取和 CSV 的写出全在你的浏览器里完成，所以银行对账单或工资表绝不会离开你打开它的这台机器。没有账户，没有每日上限，断网时这款工具照样能用。