有没有一种简单的方法来输出逐列CSV? [英] Is there an easy way to output a column-wise CSV?
问题描述
我试图输出数据的多个列表,长短不一,为CSV文件。每个列表应该在输出CSV文件的一列。是否有这样做的事情的一个直接的方法是什么?如果我每个列表输出为行,我只是遍历每个列表和产出回报,当我打到最后,但工作列方式时,这种方法是行不通的。
I'm trying to output multiple lists of data, of varying length, to a CSV file. Each list should be a column in the output CSV file. Is there a straight-forward way of doing thing? If I were outputting each list as a row, I'd just loop over each list and output a return when I hit the end, but this approach does not work when working column-wise.
我想过要去了所有列表一次,逐项递增一个计数器,而且这也将失败,因为一些表是比别人更长的时间。为了解决这个问题,我将不得不检查在每次迭代计数器是否是过去的每个列表的结束,这将是相当昂贵的计算方面
I thought of going over all the lists at once, item by item and incrementing a counter, but this would also fail because some lists are longer than others. To remedy this I would have to check at each iteration whether the counter is past the end of each list, which would be fairly expensive in terms of computations.
感谢您的想法!
推荐答案
我觉得这是pretty的直接的:
I think this is pretty straight-forward:
public static void main(String... args) throws IOException {
ArrayList<ArrayList<String>> rows = getRandomData();
if (rows.size() == 0)
throw new RuntimeException("No rows");
// normalize data
int longest = 0;
for (List<String> row : rows)
if (row.size() > longest)
longest = row.size();
for (List<String> row : rows)
while (row.size() < longest)
row.add("");
if (longest == 0)
throw new RuntimeException("No colums");
// fix special characters
for (int i = 0; i < rows.size(); i++)
for (int j = 0; j < rows.get(i).size(); j++)
rows.get(i).set(j, fixSpecial(rows.get(i).get(j)));
// get the maximum size of one column
int[] maxColumn = new int[rows.get(0).size()];
for (int i = 0; i < rows.size(); i++)
for (int j = 0; j < rows.get(i).size(); j++)
if (maxColumn[j] < rows.get(i).get(j).length())
maxColumn[j] = rows.get(i).get(j).length();
// create the format string
String outFormat = "";
for (int max : maxColumn)
outFormat += "%-" + (max + 1) + "s, ";
outFormat = outFormat.substring(0, outFormat.length() - 2) + "\n";
// print the data
for (List<String> row : rows)
System.out.printf(outFormat, row.toArray());
}
private static String fixSpecial(String s) {
s = s.replaceAll("(\")", "$1$1");
if (s.contains("\n") || s.contains(",") || s.contains("\"") ||
s.trim().length() < s.length()) {
s = "\"" + s + "\"";
}
return s;
}
private static ArrayList<ArrayList<String>> getRandomData() {
ArrayList<ArrayList<String>> data = new ArrayList<ArrayList<String>>();
String[] rand = { "Do", "Re", "Song", "David", "Test", "4", "Hohjoh", "a \"h\" o", "tjo,ad" };
Random r = new Random(5);
for (int i = 0; i < 10; i++) {
ArrayList<String> row = new ArrayList<String>();
for (int j = 0; j < r.nextInt(10); j++)
row.add(rand[r.nextInt(rand.length)]);
data.add(row);
}
return data;
}
输出(因为它的随机pretty的丑陋)(逃逸):
Re , 4 , "tjo,ad" , "tjo,ad" ,
"tjo,ad" , "a ""h"" o" , , ,
Re , "a ""h"" o" , Hohjoh , "tjo,ad" , 4
4 , David , , ,
4 , Test , "tjo,ad" , Hohjoh , Re
Do , Hohjoh , Test , ,
Hohjoh , Song , , ,
4 , Song , , ,
4 , Do , Song , Do ,
Song , Test , Test , ,
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