7TensorBoard的使用（一）

transform在Dateset中很常用，主要是对图像进行一个变化，例如统一到统一的尺寸；或对图像中的数据进行每一个类的转化。若要演示transform的结果，肯定涉及到运行一个方法后展示这个图像，最简单的方法就是TensorBoard。可是使用它展示loss变化，进行模型选择。展示out_put。

pip install tensorboard

“ctrl+点击查看help”

class SummaryWriter(object):
    """Writes entries directly to event files in the log_dir to be
    consumed by TensorBoard.

    The `SummaryWriter` class provides a high-level API to create an event file
    in a given directory and add summaries and events to it. The class updates the
    file contents asynchronously. This allows a training program to call methods
    to add data to the file directly from the training loop, without slowing down
    training.
    """

由初始化可以看出其需要几个参数，常用第一个，“log_dir”文件位置。

 def __init__(self, log_dir=None, comment='', purge_step=None, max_queue=10,
                 flush_secs=120, filename_suffix=''):

创建实例

from torch.utils.tensorboard import SummaryWriter

writer = SummaryWriter('logs')

writer.add_image()

# scalar标量
writer.add_scalar()

writer.close()

构造train_loss类似的方式

（首先将add_image()方法注释掉，用不上）
参数解释

 def add_scalar(
        self,
        tag,
        scalar_value,
        global_step=None,
        walltime=None,
        new_style=False,
        double_precision=False,
    ):

创建一个实例y=x

from torch.utils.tensorboard import SummaryWriter

writer = SummaryWriter('logs')

# writer.add_image()


# y=x
for i in range(100):
    writer.add_scalar("y=x",i,i)     # scalar标量


writer.close()

尝试打开log文件
可使用conda命令或pycharm的Terminal终端：
tensorboard --logdir=logs
可按ctrl+c进行取消

若多人访问地址，防止冲突：选择6007端口
tensorboard --logdir=logs --port=6007

from torch.utils.tensorboard import SummaryWriter

writer = SummaryWriter('logs')

# writer.add_image()


# y=2x
for i in range(100):
    writer.add_scalar("y=2x",2*i,i)     # scalar标量


writer.close()

存在一种问题情况，如不更改参数tag，仅更改参数scalar_value：3*i

from torch.utils.tensorboard import SummaryWriter

writer = SummaryWriter('logs')

# writer.add_image()


# y=2x
for i in range(100):
    writer.add_scalar("y=2x",3*i,i)     # scalar标量


writer.close()

会出现和上一次的重合

两种解决办法：1删除所有的log文件再运行一次；2新建子文件夹放进去日志文件

接下来讲解该怎么向里面写入一些图像