我正在创建一个应用程序，我可以在其中进行实时图像分析并将它们存储到csv文件中。 csv具有2列时间和每帧的y值。
我想读取此文件并将2列中的值存储到double数组中。我想要这个，因为我想对数据进行快速傅里叶变换。
public class MainActivity extends AppCompatActivity implements CameraView.PreviewReadyCallback {
private static Camera camera = null;
private CameraView image = null;
private LineChart bp_graph;
private int img_Y_Avg, img_U_Avg, img_V_Avg;
private long end = 0, begin = 0;
double valueY, valueU, valueV;
Handler handler;
private int readingRemaining = 1200;
private static long time1, time2, timeDifference;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
bp_graph = (LineChart)findViewById(R.id.graph);
graph_features();
//open camera
try {
camera = Camera.open();
handler = new Handler();
final Runnable runnable = new Runnable() {
@Override
public void run() {
camera.stopPreview();
camera.release();
}
};
handler.postDelayed(runnable, 30000);
} catch (Exception e) {
Log.d("ERROR", "Failed to get camera: " + e.getMessage());
}
if (camera != null) {
image = new CameraView(this, camera);
FrameLayout camera_view = (FrameLayout) findViewById(R.id.camera_view);
camera_view.addView(image);
image.setOnPreviewReady(this);
}
}
@Override
protected void onResume(){
super.onResume();
}
@Override
protected void onPause() {
super.onPause();
}
@Override
public void onPreviewFrame(long startTime, int ySum, int uSum, int vSum, long endTime) {
begin = startTime;
img_Y_Avg = ySum;
img_U_Avg = uSum;
img_V_Avg = vSum;
end = endTime;
showResults(begin, img_Y_Avg, img_U_Avg, img_V_Avg, end);
}
private void showResults(long startTime, int ySum, int uSum, int vSum, long endTime){
//set value of Y on the text view
TextView valueOfY = (TextView)findViewById(R.id.valueY);
//valueY = img_Y_Avg;
valueOfY.setText(String.valueOf(img_Y_Avg));
//start time in milliseconds
long StartDurationInMs = TimeUnit.MILLISECONDS.convert(begin, TimeUnit.MILLISECONDS);
ArrayList<Long> startOfTime = new ArrayList<>();
startOfTime.add(StartDurationInMs);
//store value to array list
ArrayList<Integer> yAverage = new ArrayList<>();
yAverage.add(img_Y_Avg);
//convert to readable format
String readableDate = new SimpleDateFormat("MMM dd,yyyy, HH:mm:ss.SSS").format(EndDurationInMs);
Log.d("Date ", readableDate);
Log.d("time ", String.valueOf(String.valueOf(yAverage.size())));
//store when all array are generated
Log.d("time ", String.valueOf(StartDurationInMs));
ArrayList<Long> getValues = new ArrayList<>();
for(int i = 0; i < yAverage.size(); i++) {
getValues.add(startOfTime.get(i));
getValues.add((long)(yAverage.get(i)));
}
//store the yAverage and start time to csv file
storeCsv(yAverage, getValues);
Log.d("MyEntryData", String.valueOf(getValues));
}
public void storeCsv(ArrayList<Integer>yAverage, ArrayList<Long>getValues){
String filename = "temporary.csv";
//File directoryDownload = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/bpReader";
//File logDir = new File (directoryDownload, "bpReader"); //Creates a new folder in DOWNLOAD directory
File logDir = new File(path);
logDir.mkdirs();
File file = new File(logDir, filename);
FileOutputStream outputStream = null;
try {
file.createNewFile();
outputStream = new FileOutputStream(file, true);
//outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
for (int i = 0; i < yAverage.size(); i += 2) {
outputStream.write((getValues.get(i) + ",").getBytes());
outputStream.write((getValues.get(i + 1) + "\n").getBytes());
//outputStream.write((getValues.get(i + 2) + ",").getBytes());
//outputStream.write((getValues.get(i + 3) + "\n").getBytes());
}
outputStream.flush();
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void readCsv(){
}
}
这是我的 MainActivity 。我在这里做的是借助我创建的界面从每个帧的 CameraView 类获取数据。之后，我将值存储到名为 temporary.csv 的CSV文件中。
问题
我该怎么做？
答案 0 :(得分：1)
我建议您使用OpenCSV等开源库从CSV文件中获取数据。当您实现库时，只需迭代x和y列并将它们分配给数组即可。使用OpenCSV，它看起来就像那样。但是如果具有相同索引坐标的x和y彼此相关，我还建议你使用更多对象orientec方法。
String csvFile = "/Users/mkyong/csv/country3.csv";
int length = 100; //If you dont know how many entries the csv file has i would suggest to use ArrayList
double[] xCoords = new double[length];
double[] yCoords = new double[length];
CSVReader reader = null;
try {
reader = new CSVReader(new FileReader(csvFile));
String[] line;
int i = 0;
while ((line = reader.readNext()) != null) {
xCoords[i] = Double.parseDouble(line[0]);
yCoords[i] = Double.parseDouble(line[1]);
}
} catch (IOException e) {
e.printStackTrace();
}
答案 1 :(得分：0)
从卢卡斯的回答中，我得到了解决方案的方向
public void readCsv(){
//set the path to the file
String getPath = Environment.getExternalStorageDirectory() + "/bpReader";
String csvFile = "temporary.csv";
String path = getPath+ "/" + csvFile;
//File file = new File(path, csvFile);
int length = 500;
double[] xCoords = new double[length];
double[] yCoords = new double[length];
CSVReader reader = null;
try {
File myFile = new File (path);
reader = new CSVReader(new FileReader(myFile));
String[] line;
int i = 0;
while ((line = reader.readNext()) != null) {
xCoords[i] = Double.parseDouble(line[0]) ;
yCoords[i] = Double.parseDouble(line[1]);
Log.d("read:: ", "Time: "+String.valueOf(xCoords[i])+" Y: "+String.valueOf(yCoords[i]));
}
myFile.delete();
} catch (IOException e) {
e.printStackTrace();
}
}
然后我不得不添加
// https://mvnrepository.com/artifact/org.apache.commons/commons-lang3
compile group: 'org.apache.commons', name: 'commons-lang3', version: '3.6'
到我的gradle ,,可以在MVN repository
找到