手写实现reduce
时间: 2023-11-30 13:43:04 浏览: 30
以下是手写实现reduce的示例代码:
```python
def my_reduce(func, seq, init=None):
it = iter(seq)
if init is None:
value = next(it)
else:
value = init
for element in it:
value = func(value, element)
return value
```
这个函数接收三个参数:一个函数(用于累加操作)、一个序列和一个可选的初始值。它模拟了Python内置的reduce()函数的功能,对序列中的元素进行累加操作,最终返回一个值。
示例用法:
```python
# 对列表中的元素求和
my_list = [1, 2, 3, 4, 5]
result = my_reduce(lambda x, y: x + y, my_list)
print(result) # 输出:15
# 对列表中的元素求积
my_list = [1, 2, 3, 4, 5]
result = my_reduce(lambda x, y: x * y, my_list)
print(result) # 输出:120
```
相关问题
利用TensorFlow实现识别手写数字
以下是一个简单的示例,使用TensorFlow来实现手写数字的识别:
1. 导入必要的库
```python
import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data
```
2. 加载MNIST数据集
```python
mnist = input_data.read_data_sets("MNIST_data/", one_hot=True)
```
3. 构建模型
```python
x = tf.placeholder(tf.float32, [None, 784]) # 输入层
y_ = tf.placeholder(tf.float32, [None, 10]) # 输出层
W = tf.Variable(tf.zeros([784, 10])) # 权重
b = tf.Variable(tf.zeros([10])) # 偏置
y = tf.nn.softmax(tf.matmul(x, W) + b) # 模型输出
```
4. 定义损失函数和优化器
```python
cross_entropy = tf.reduce_mean(-tf.reduce_sum(y_ * tf.log(y), reduction_indices=[1])) # 交叉熵损失函数
train_step = tf.train.GradientDescentOptimizer(0.5).minimize(cross_entropy) # 梯度下降优化器
```
5. 训练模型
```python
sess = tf.InteractiveSession()
tf.global_variables_initializer().run()
for i in range(1000):
batch_xs, batch_ys = mnist.train.next_batch(100)
sess.run(train_step, feed_dict={x: batch_xs, y_: batch_ys})
```
6. 评估模型
```python
correct_prediction = tf.equal(tf.argmax(y,1), tf.argmax(y_,1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
print(sess.run(accuracy, feed_dict={x: mnist.test.images, y_: mnist.test.labels}))
```
完整代码如下:
```python
import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets("MNIST_data/", one_hot=True)
x = tf.placeholder(tf.float32, [None, 784])
y_ = tf.placeholder(tf.float32, [None, 10])
W = tf.Variable(tf.zeros([784, 10]))
b = tf.Variable(tf.zeros([10]))
y = tf.nn.softmax(tf.matmul(x, W) + b)
cross_entropy = tf.reduce_mean(-tf.reduce_sum(y_ * tf.log(y), reduction_indices=[1]))
train_step = tf.train.GradientDescentOptimizer(0.5).minimize(cross_entropy)
sess = tf.InteractiveSession()
tf.global_variables_initializer().run()
for i in range(1000):
batch_xs, batch_ys = mnist.train.next_batch(100)
sess.run(train_step, feed_dict={x: batch_xs, y_: batch_ys})
correct_prediction = tf.equal(tf.argmax(y,1), tf.argmax(y_,1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
print(sess.run(accuracy, feed_dict={x: mnist.test.images, y_: mnist.test.labels}))
```
输出结果为识别准确率,大约为91%。
vue手写实现移动端el-table组件
好的,我会给您提供一些实现思路和代码示例。
首先,我们可以在组件中定义表头和表格数据的prop,以及一些表格的基本配置参数。如下所示:
```javascript
props: {
columns: {
type: Array,
default: () => []
},
data: {
type: Array,
default: () => []
},
rowKey: {
type: String,
default: 'id'
},
height: {
type: [String, Number],
default: 'auto'
},
pageSize: {
type: Number,
default: 10
},
showPagination: {
type: Boolean,
default: true
},
showIndex: {
type: Boolean,
default: true
},
showHeader: {
type: Boolean,
default: true
},
border: {
type: Boolean,
default: true
}
},
```
接下来,我们可以利用计算属性来实现表格的响应式布局。例如,计算列宽度的方法可以如下所示:
```javascript
computed: {
tableWidth() {
return this.columns.reduce((total, column) => {
return total + (column.width || 100)
}, 0)
},
tableHeight() {
if (this.height === 'auto') {
return 'auto'
} else {
return `${this.height}px`
}
},
cellStyle() {
return {
width: `${(100 / this.columns.length).toFixed(2)}%`
}
},
thStyle() {
return {
width: `${(100 / this.columns.length).toFixed(2)}%`
}
}
},
```
然后,我们可以在模板中渲染表格的各个部分,如表格头部、表格内容、分页等。例如,表格头部的渲染代码可以如下所示:
```html
<template>
<table class="el-table" :style="{ width: tableWidth, height: tableHeight, border: border ? '1px solid #ccc' : 'none' }">
<colgroup>
<col v-if="showIndex" style="width: 50px;">
<col v-for="(column, index) in columns" :key="index" :style="cellStyle">
</colgroup>
<thead v-show="showHeader">
<tr>
<th v-if="showIndex">序号</th>
<th v-for="(column, index) in columns" :key="index" :style="thStyle">{{ column.title }}</th>
</tr>
</thead>
<tbody>
...
</tbody>
</table>
</template>
```
最后,我们可以在组件中实现表格的分页、排序、搜索等功能,以及一些交互效果。例如,分页功能的实现代码可以如下所示:
```javascript
computed: {
pageCount() {
return Math.ceil(this.data.length / this.pageSize)
},
currentData() {
const start = (this.currentPage - 1) * this.pageSize
const end = start + this.pageSize
return this.data.slice(start, end)
}
},
methods: {
handlePageChange(currentPage) {
this.currentPage = currentPage
}
}
```
```html
<template>
<div>
<table class="el-table" :style="{ width: tableWidth, height: tableHeight, border: border ? '1px solid #ccc' : 'none' }">
...
</table>
<el-pagination v-if="showPagination"
:current-page.sync="currentPage"
:page-size="pageSize"
:total="data.length"
@current-change="handlePageChange">
</el-pagination>
</div>
</template>
```
以上就是一个简单的移动端el-table组件的实现思路和代码示例。希望能对您有所帮助。