Java tutorial
/* * Copyright 2017 TWO SIGMA OPEN SOURCE, LLC * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.twosigma.beaker.fileloader; import com.github.lwhite1.tablesaw.api.Table; import org.apache.commons.lang3.math.NumberUtils; import java.io.IOException; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.*; public class CsvPlotReader { private static String TIME_COLUMN = "time"; public List<Map<?, ?>> convert(Table table) { List<Map<?, ?>> result = new ArrayList<>(); for (int r = 0; r < table.rowCount(); r++) { Map<String, Object> entry = new HashMap<>(); for (int c = 0; c < table.columnCount(); c++) { Object value = table.get(c, r); String headerName = table.columnNames().get(c); if (headerName.equals(TIME_COLUMN)) { entry.put(headerName, convertDate(value)); } else { entry.put(headerName, convertToNumber(value)); } } result.add(entry); } return result; } public Table read(String fileName) throws IOException { return Table.createFromCsv(fileName); } public List<Map<?, ?>> readAsList(String fileName) throws IOException { return convert(Table.createFromCsv(fileName)); } private Object convertToNumber(Object value) { if (value instanceof String && NumberUtils.isNumber((String) value)) { return Float.parseFloat((String) value); } else { return value; } } private Object convertDate(Object x) { if (x instanceof Number) { return x; } else if (x instanceof Date) { Date date = (Date) x; return date.getTime(); } else if (x instanceof String) { Date inputDate = null; try { inputDate = new SimpleDateFormat("yyyy-MM-dd").parse((String) x); } catch (ParseException e) { throw new IllegalArgumentException( "time column accepts String date in a following format yyyy-MM-dd"); } return inputDate.getTime(); } else { throw new IllegalArgumentException( "time column accepts numbers or java.util.Date objects or String date in a following format yyyy-MM-dd"); } } }