Tensorflowsharp从入门到放弃（二）——这次有个手写数字识别
接上文，源代码是控制台的：所有输出Console.WriteLine(*);这样的代码一致改为this.textBox1.Text +="\r\n"+ string.Format(*);
这次又更新了四课内容，其中手写数字识别卡住了一会，主要原因是网上 TF#的MNIST手写数字识别代码太多太乱，此处补上最新版的（也是原作者的代码）供后人学习。
///
/// 06 线性回归（没实现）
///
private void button6_Click(object sender, EventArgs e)
{
// 创建所需数据
var xList = new List();
var yList = new List();
var ran = new Random();
for (var i = 0; i < 10; i++)
{
var num = ran.NextDouble();
var noise = ran.NextDouble();
xList.Add(num);
yList.Add(num * 3 + 4 + noise); // y = 3 * x + 4
}
var xData = xList.ToArray();
var yData = yList.ToArray();
var learning_rate = 0.01;
// 创建图
var g = new TFGraph();
// 创建占位符
var x = g.Placeholder(TFDataType.Double, new TFShape(xData.Length));
var y = g.Placeholder(TFDataType.Double, new TFShape(yData.Length));
// 权重和偏置
var W = g.VariableV2(TFShape.Scalar, TFDataType.Double, operName: "weight");
var b = g.VariableV2(TFShape.Scalar, TFDataType.Double, operName: "bias");
var initW = g.Assign(W, g.Const(ran.NextDouble()));
var initb = g.Assign(b, g.Const(ran.NextDouble()));
var output = g.Add(g.Mul(x, W), b);
// 损失
var loss = g.ReduceSum(g.Abs(g.Sub(output, y)));
var grad = g.AddGradients(new TFOutput[] { loss }, new TFOutput[] { W, b });
var optimize = new[]
{
g.AssignSub(W, g.Mul(grad[0], g.Const(learning_rate))).Operation,
g.AssignSub(b, g.Mul(grad[1], g.Const(learning_rate))).Operation
};
// 创建会话
var sess = new TFSession(g);
// 变量初始化
sess.GetRunner().AddTarget(initW.Operation, initb.Operation).Run();
// 进行训练拟合
for (var i = 0; i < 1000; i++)
{
var result = sess.GetRunner()
.AddInput(x, xData)
.AddInput(y, yData)
.AddTarget(optimize)
.Fetch(loss, W, b).Run();
this.textBox1.Text = string.Format("loss: {0} W:{1} b:{2}", result[0].GetValue(), result[1].GetValue(), result[2].GetValue());
}
}
///
/// 07 手写数字识别
///
private void button7_Click(object sender, EventArgs e)
{
// 加载手写数字资源
var mnist = Mnist.Load();
// 训练次数和测试次数
var trainCount = 5000;
var testCount = 200;
// 获取训练图片、训练图片标签、测试图片、测试图片标签
float[,] trainingImages, trainingLabels, testImages, testLabels;
mnist.GetTrainReader().NextBatch(trainCount, out trainingImages, out trainingLabels);
mnist.GetTestReader().NextBatch(testCount, out testImages, out testLabels);
//mnist.GetTrainReader().NextBatch(trainCount);
//mnist.GetTestReader().NextBatch(testCount);
// 创建图
var g = new TFGraph();
// 训练图片占位符和训练标签占位符
var trainingInput = g.Placeholder(TFDataType.Float, new TFShape(-1, 784)); // 不定数量的像素为24*24的图片
var xte = g.Placeholder(TFDataType.Float, new TFShape(784));
// 创建计算误差和预测的图
var distance = g.ReduceSum(g.Abs(g.Add(trainingInput, g.Neg(xte))), axis: g.Const(1));
var pred = g.ArgMin(distance, g.Const(0));
// 创建会话
var sess = new TFSession(g);
// 精度
var accuracy = 0.0f;
// 进行迭代训练，并且每次都输出预测值
for (int i = 0; i < testCount; i++)
{
var runner = sess.GetRunner();
// 计算并且获取误差和预测值
var result = runner.
Fetch(pred).
Fetch(distance).
AddInput(trainingInput, trainingImages).
AddInput(xte, Extract(testImages, i)).Run();
var r = result[0].GetValue();
var tr = result[1].GetValue();
var nn_index = (int)(long)result[0].GetValue();
this.textBox1.Text += string.Format($"训练次数 {i}： 预测： { ArgMax(trainingLabels, nn_index) } 真实值： { ArgMax(testLabels, i)} (nn_index= { nn_index })");
if (ArgMax(trainingLabels, nn_index) == ArgMax(testLabels, i))
accuracy += 1f / testImages.Length;
}
// 精确度
this.textBox1.Text += string.Format("精度：" + accuracy);
}
///
/// 获取矩阵array中idx行的最大值
///
///
///
///
/// 获取矩阵array中的index行（即获取n*n图片数组中的第n张）
///
///
///
///
/// 08 张量的使用
///
private void button8_Click(object sender, EventArgs e)
{
// 整数张量
var tensor = new TFTensor(1);
this.textBox1.Text +="\r\n"+ string.Format("Value:" + tensor.GetValue());
// 矩阵张量
tensor = new TFTensor(new int[,]
{
{ 1, 2, 3 },
{ 4, 5, 6 },
});
this.textBox1.Text += "\r\n" + string.Format("TensorType: {0}", tensor.TensorType.ToString());
this.textBox1.Text += "\r\n" + string.Format("NumDims: " + tensor.NumDims);
this.textBox1.Text += "\r\n" + string.Format("Shape", string.Join(",", tensor.Shape));
for (var i = 0; i < tensor.NumDims; i++)
{
var dim = tensor.GetTensorDimension(i);
this.textBox1.Text += "\r\n" + string.Format("DimIndex: {0}, Dim: {1}", i, dim);
}
// 创建图
var g = new TFGraph();
// 创建字符串张量
tensor = new TFTensor("Hello, world!".Select(o => (sbyte)o).ToArray());
var hello = g.Const(tensor);
// 创建会话
var sess = new TFSession(g);
// 进行计算
var result = sess.GetRunner().Run(hello).GetValue();
// 输出计算结果
this.textBox1.Text += "\r\n" + string.Format(string.Join("", ((sbyte[])result).Select(o => (char)o)));
} 以下三个类文件放到自己工程下，网上很多MNIST.cs的代码有些版本不同,会有部分函数功能不同，目前最新如下：
MNIST.cs代码
//
// Code to download and load the MNIST data.
//
using System;
using System.IO;
using System.IO.Compression;
using Mono;
using TensorFlow;
using System.Linq;
namespace Learn.Mnist
{
// Stores the per-image MNIST information we loaded from disk
//
// We store the data in two formats, byte array (as it came in from disk), and float array
// where each 0..255 value has been mapped to 0.0f..1.0f
public struct MnistImage
{
public int Cols, Rows;
public byte[] Data;
public float[] DataFloat;
public MnistImage(int cols, int rows, byte[] data)
{
Cols = cols;
Rows = rows;
Data = data;
DataFloat = new float[data.Length];
for (int i = 0; i < data.Length; i++)
{
DataFloat[i] = Data[i] / 255f;
}
}
}
// Helper class used to load and work with the Mnist data set
public class Mnist
{
//
// The loaded results
//
public MnistImage[] TrainImages, TestImages, ValidationImages;
public byte[] TrainLabels, TestLabels, ValidationLabels;
public byte[,] OneHotTrainLabels, OneHotTestLabels, OneHotValidationLabels;
public BatchReader GetTrainReader() => new BatchReader(TrainImages, TrainLabels, OneHotTrainLabels);
public BatchReader GetTestReader() => new BatchReader(TestImages, TestLabels, OneHotTestLabels);
public BatchReader GetValidationReader() => new BatchReader(ValidationImages, ValidationLabels, OneHotValidationLabels);
public class BatchReader
{
int start = 0;
MnistImage[] source;
byte[] labels;
byte[,] oneHotLabels;
internal BatchReader(MnistImage[] source, byte[] labels, byte[,] oneHotLabels)
{
this.source = source;
this.labels = labels;
this.oneHotLabels = oneHotLabels;
}
public void NextBatch(int batchSize, out float[,] imageData, out float[,] labelData)
{
imageData = new float[batchSize, 784];
labelData = new float[batchSize, 10];
int p = 0;
for (int item = 0; item < batchSize; item++)
{
Buffer.BlockCopy(source[start + item].DataFloat, 0, imageData, p, 784 * sizeof(float));
p += 784 * sizeof(float);
for (var j = 0; j < 10; j++)
labelData[item, j] = oneHotLabels[item + start, j];
}
start += batchSize;
}
}
int Read32(Stream s)
{
var x = new byte[4];
s.Read(x, 0, 4);
return DataConverter.BigEndian.GetInt32(x, 0);
}
MnistImage[] ExtractImages(Stream input, string file)
{
using (var gz = new GZipStream(input, CompressionMode.Decompress))
{
if (Read32(gz) != 2051)
throw new Exception("Invalid magic number found on the MNIST " + file);
var count = Read32(gz);
var rows = Read32(gz);
var cols = Read32(gz);
var result = new MnistImage[count];
for (int i = 0; i < count; i++)
{
var size = rows * cols;
var data = new byte[size];
gz.Read(data, 0, size);
result[i] = new MnistImage(cols, rows, data);
}
return result;
}
}
byte[] ExtractLabels(Stream input, string file)
{
using (var gz = new GZipStream(input, CompressionMode.Decompress))
{
if (Read32(gz) != 2049)
throw new Exception("Invalid magic number found on the MNIST " + file);
var count = Read32(gz);
var labels = new byte[count];
gz.Read(labels, 0, count);
return labels;
}
}
T[] Pick(T[] source, int first, int last)
{
if (last == 0)
last = source.Length;
var count = last - first;
var result = new T[count];
Array.Copy(source, first, result, 0, count);
return result;
}
// Turn the labels array that contains values 0..numClasses-1 into
// a One-hot encoded array
byte[,] OneHot(byte[] labels, int numClasses)
{
var oneHot = new byte[labels.Length, numClasses];
for (int i = 0; i < labels.Length; i++)
{
oneHot[i, labels[i]] = 1;
}
return oneHot;
}
///
/// Reads the data sets.
///
/// Directory where the training data is downlaoded to.
/// Number classes to use for one-hot encoding, or zero if this is not desired
/// Validation size.
public void ReadDataSets(string trainDir, int numClasses = 10, int validationSize = 5000)
{
const string SourceUrl = "http://yann.lecun.com/exdb/mnist/";
const string TrainImagesName = "train-images-idx3-ubyte.gz";
const string TrainLabelsName = "train-labels-idx1-ubyte.gz";
const string TestImagesName = "t10k-images-idx3-ubyte.gz";
const string TestLabelsName = "t10k-labels-idx1-ubyte.gz";
TrainImages = ExtractImages(Helper.MaybeDownload(SourceUrl, trainDir, TrainImagesName), TrainImagesName);
TestImages = ExtractImages(Helper.MaybeDownload(SourceUrl, trainDir, TestImagesName), TestImagesName);
TrainLabels = ExtractLabels(Helper.MaybeDownload(SourceUrl, trainDir, TrainLabelsName), TrainLabelsName);
TestLabels = ExtractLabels(Helper.MaybeDownload(SourceUrl, trainDir, TestLabelsName), TestLabelsName);
ValidationImages = Pick(TrainImages, 0, validationSize);
ValidationLabels = Pick(TrainLabels, 0, validationSize);
TrainImages = Pick(TrainImages, validationSize, 0);
TrainLabels = Pick(TrainLabels, validationSize, 0);
if (numClasses != -1)
{
OneHotTrainLabels = OneHot(TrainLabels, numClasses);
OneHotValidationLabels = OneHot(ValidationLabels, numClasses);
OneHotTestLabels = OneHot(TestLabels, numClasses);
}
}
public static Mnist Load()
{
var x = new Mnist();
x.ReadDataSets(Environment.CurrentDirectory + "\\tmp");
return x;
}
}
}
DataConverter.cs文件
//
// Authors:
// Miguel de Icaza ([email protected])
//
// See the following url for documentation:
// http://www.mono-project.com/Mono_DataConvert
//
// Compilation Options:
// MONO_DATACONVERTER_PUBLIC:
// Makes the class public instead of the default internal.
//
// MONO_DATACONVERTER_STATIC_METHODS:
// Exposes the public static methods.
//
// TODO:
// Support for "DoubleWordsAreSwapped" for ARM devices
//
// Copyright (C) 2006 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
#define MONO_DATACONVERTER_PUBLIC
using System;
using System.Collections;
using System.Text;
using System.Collections.Generic;
#pragma warning disable 3021
namespace Mono
{
#if MONO_DATACONVERTER_PUBLIC
public
#endif
unsafe abstract class DataConverter
{
// Disables the warning: CLS compliance checking will not be performed on
// `XXXX' because it is not visible from outside this assembly
#pragma warning disable 3019
static readonly DataConverter SwapConv = new SwapConverter();
static readonly DataConverter CopyConv = new CopyConverter();
public static readonly bool IsLittleEndian = BitConverter.IsLittleEndian;
public abstract double GetDouble(byte[] data, int index);
public abstract float GetFloat(byte[] data, int index);
public abstract long GetInt64(byte[] data, int index);
public abstract int GetInt32(byte[] data, int index);
public abstract short GetInt16(byte[] data, int index);
[CLSCompliant(false)]
public abstract uint GetUInt32(byte[] data, int index);
[CLSCompliant(false)]
public abstract ushort GetUInt16(byte[] data, int index);
[CLSCompliant(false)]
public abstract ulong GetUInt64(byte[] data, int index);
public abstract void PutBytes(byte[] dest, int destIdx, double value);
public abstract void PutBytes(byte[] dest, int destIdx, float value);
public abstract void PutBytes(byte[] dest, int destIdx, int value);
public abstract void PutBytes(byte[] dest, int destIdx, long value);
public abstract void PutBytes(byte[] dest, int destIdx, short value);
[CLSCompliant(false)]
public abstract void PutBytes(byte[] dest, int destIdx, ushort value);
[CLSCompliant(false)]
public abstract void PutBytes(byte[] dest, int destIdx, uint value);
[CLSCompliant(false)]
public abstract void PutBytes(byte[] dest, int destIdx, ulong value);
public byte[] GetBytes(double value)
{
byte[] ret = new byte[8];
PutBytes(ret, 0, value);
return ret;
}
public byte[] GetBytes(float value)
{
byte[] ret = new byte[4];
PutBytes(ret, 0, value);
return ret;
}
public byte[] GetBytes(int value)
{
byte[] ret = new byte[4];
PutBytes(ret, 0, value);
return ret;
}
public byte[] GetBytes(long value)
{
byte[] ret = new byte[8];
PutBytes(ret, 0, value);
return ret;
}
public byte[] GetBytes(short value)
{
byte[] ret = new byte[2];
PutBytes(ret, 0, value);
return ret;
}
[CLSCompliant(false)]
public byte[] GetBytes(ushort value)
{
byte[] ret = new byte[2];
PutBytes(ret, 0, value);
return ret;
}
[CLSCompliant(false)]
public byte[] GetBytes(uint value)
{
byte[] ret = new byte[4];
PutBytes(ret, 0, value);
return ret;
}
[CLSCompliant(false)]
public byte[] GetBytes(ulong value)
{
byte[] ret = new byte[8];
PutBytes(ret, 0, value);
return ret;
}
static public DataConverter LittleEndian
{
get
{
return BitConverter.IsLittleEndian ? CopyConv : SwapConv;
}
}
static public DataConverter BigEndian
{
get
{
return BitConverter.IsLittleEndian ? SwapConv : CopyConv;
}
}
static public DataConverter Native
{
get
{
return CopyConv;
}
}
static int Align(int current, int align)
{
return ((current + align - 1) / align) * align;
}
class PackContext
{
// Buffer
public byte[] buffer;
int next;
public string description;
public int i; // position in the description
public DataConverter conv;
public int repeat;
//
// if align == -1, auto align to the size of the byte array
// if align == 0, do not do alignment
// Any other values aligns to that particular size
//
public int align;
public void Add(byte[] group)
{
//Console.WriteLine ("Adding {0} bytes to {1} (next={2}", group.Length,
// buffer == null ? "null" : buffer.Length.ToString (), next);
if (buffer == null)
{
buffer = group;
next = group.Length;
return;
}
if (align != 0)
{
if (align == -1)
next = Align(next, group.Length);
else
next = Align(next, align);
align = 0;
}
if (next + group.Length > buffer.Length)
{
byte[] nb = new byte[System.Math.Max(next, 16) * 2 + group.Length];
Array.Copy(buffer, nb, buffer.Length);
Array.Copy(group, 0, nb, next, group.Length);
next = next + group.Length;
buffer = nb;
}
else
{
Array.Copy(group, 0, buffer, next, group.Length);
next += group.Length;
}
}
public byte[] Get()
{
if (buffer == null)
return new byte[0];
if (buffer.Length != next)
{
byte[] b = new byte[next];
Array.Copy(buffer, b, next);
return b;
}
return buffer;
}
}
//
// Format includes:
// Control:
// ^ Switch to big endian encoding
// _ Switch to little endian encoding
// % Switch to host (native) encoding
// ! aligns the next data type to its natural boundary (for strings this is 4).
//
// Types:
// s Int16
// S UInt16
// i Int32
// I UInt32
// l Int64
// L UInt64
// f float
// d double
// b byte
// c 1-byte signed character
// C 1-byte unsigned character
// z8 string encoded as UTF8 with 1-byte null terminator
// z6 string encoded as UTF16 with 2-byte null terminator
// z7 string encoded as UTF7 with 1-byte null terminator
// zb string encoded as BigEndianUnicode with 2-byte null terminator
// z3 string encoded as UTF32 with 4-byte null terminator
// z4 string encoded as UTF32 big endian with 4-byte null terminator
// $8 string encoded as UTF8
// $6 string encoded as UTF16
// $7 string encoded as UTF7
// $b string encoded as BigEndianUnicode
// $3 string encoded as UTF32
// $4 string encoded as UTF-32 big endian encoding
// x null byte
//
// Repeats, these are prefixes:
// N a number between 1 and 9, indicates a repeat count (process N items
// with the following datatype
// [N] For numbers larger than 9, use brackets, for example [20]
// * Repeat the next data type until the arguments are exhausted
//
static public byte[] Pack(string description, params object[] args)
{
int argn = 0;
PackContext b = new PackContext();
b.conv = CopyConv;
b.description = description;
for (b.i = 0; b.i < description.Length;)
{
object oarg;
if (argn < args.Length)
oarg = args[argn];
else
{
if (b.repeat != 0)
break;
oarg = null;
}
int save = b.i;
if (PackOne(b, oarg))
{
argn++;
if (b.repeat > 0)
{
if (--b.repeat > 0)
b.i = save;
else
b.i++;
}
else
b.i++;
}
else
b.i++;
}
return b.Get();
}
static public byte[] PackEnumerable(string description, IEnumerable args)
{
PackContext b = new PackContext();
b.conv = CopyConv;
b.description = description;
IEnumerator enumerator = args.GetEnumerator();
bool ok = enumerator.MoveNext();
for (b.i = 0; b.i < description.Length;)
{
object oarg;
if (ok)
oarg = enumerator.Current;
else
{
if (b.repeat != 0)
break;
oarg = null;
}
int save = b.i;
if (PackOne(b, oarg))
{
ok = enumerator.MoveNext();
if (b.repeat > 0)
{
if (--b.repeat > 0)
b.i = save;
else
b.i++;
}
else
b.i++;
}
else
b.i++;
}
return b.Get();
}
//
// Packs one datum `oarg' into the buffer `b', using the string format
// in `description' at position `i'
//
// Returns: true if we must pick the next object from the list
//
static bool PackOne(PackContext b, object oarg)
{
int n;
switch (b.description[b.i])
{
case '^':
b.conv = BigEndian;
return false;
case '_':
b.conv = LittleEndian;
return false;
case '%':
b.conv = Native;
return false;
case '!':
b.align = -1;
return false;
case 'x':
b.Add(new byte[] { 0 });
return false;
// Type Conversions
case 'i':
b.Add(b.conv.GetBytes(Convert.ToInt32(oarg)));
break;
case 'I':
b.Add(b.conv.GetBytes(Convert.ToUInt32(oarg)));
break;
case 's':
b.Add(b.conv.GetBytes(Convert.ToInt16(oarg)));
break;
case 'S':
b.Add(b.conv.GetBytes(Convert.ToUInt16(oarg)));
break;
case 'l':
b.Add(b.conv.GetBytes(Convert.ToInt64(oarg)));
break;
case 'L':
b.Add(b.conv.GetBytes(Convert.ToUInt64(oarg)));
break;
case 'f':
b.Add(b.conv.GetBytes(Convert.ToSingle(oarg)));
break;
case 'd':
b.Add(b.conv.GetBytes(Convert.ToDouble(oarg)));
break;
case 'b':
b.Add(new byte[] { Convert.ToByte(oarg) });
break;
case 'c':
b.Add(new byte[] { (byte)(Convert.ToSByte(oarg)) });
break;
case 'C':
b.Add(new byte[] { Convert.ToByte(oarg) });
break;
// Repeat acount;
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
b.repeat = ((short)b.description[b.i]) - ((short)'0');
return false;
case '*':
b.repeat = Int32.MaxValue;
return false;
case '[':
int count = -1, j;
for (j = b.i + 1; j < b.description.Length; j++)
{
if (b.description[j] == ']')
break;
n = ((short)b.description[j]) - ((short)'0');
if (n >= 0 && n <= 9)
{
if (count == -1)
count = n;
else
count = count * 10 + n;
}
}
if (count == -1)
throw new ArgumentException("invalid size specification");
b.i = j;
b.repeat = count;
return false;
case '$':
case 'z':
bool add_null = b.description[b.i] == 'z';
b.i++;
if (b.i >= b.description.Length)
throw new ArgumentException("$ description needs a type specified", "description");
char d = b.description[b.i];
Encoding e;
switch (d)
{
case '8':
e = Encoding.UTF8;
n = 1;
break;
case '6':
e = Encoding.Unicode;
n = 2;
break;
case '7':
#if PCL
e = Encoding.GetEncoding ("utf-7");
#else
e = Encoding.UTF7;
#endif
n = 1;
break;
case 'b':
e = Encoding.BigEndianUnicode;
n = 2;
break;
case '3':
#if PCL
e = Encoding.GetEncoding ("utf-32");
#else
e = Encoding.GetEncoding(12000);
#endif
n = 4;
break;
case '4':
#if PCL
e = Encoding.GetEncoding ("utf-32BE");
#else
e = Encoding.GetEncoding(12001);
#endif
n = 4;
break;
default:
throw new ArgumentException("Invalid format for $ specifier", "description");
}
if (b.align == -1)
b.align = 4;
b.Add(e.GetBytes(Convert.ToString(oarg)));
if (add_null)
b.Add(new byte[n]);
break;
default:
throw new ArgumentException(String.Format("invalid format specified `{0}'",
b.description[b.i]));
}
return true;
}
static bool Prepare(byte[] buffer, ref int idx, int size, ref bool align)
{
if (align)
{
idx = Align(idx, size);
align = false;
}
if (idx + size > buffer.Length)
{
idx = buffer.Length;
return false;
}
return true;
}
static public IList Unpack(string description, byte[] buffer, int startIndex)
{
DataConverter conv = CopyConv;
var result = new Listhelp.cs
using System;
using System.IO;
using System.Net;
namespace Learn
{
public class Helper
{
public static Stream MaybeDownload(string urlBase, string trainDir, string file)
{
if (!Directory.Exists(trainDir))
Directory.CreateDirectory(trainDir);
var target = Path.Combine(trainDir, file);
if (!File.Exists(target))
{
var wc = new WebClient();
wc.DownloadFile(urlBase + file, target);
}
return File.OpenRead(target);
}
}
}
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