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公告

• Creating a DataFrame
• Location
• type transforming
• Groupby and agg
• Example
  • Example 1

Creating a DataFrame

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import pandas as pd
df = pd.read_csv("a.csv")
df = pd.DataFrame({dict_t}) #convert a dict to a dataframe
df = Series_t.to_frame()

Location

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df.loc[0:4,"Year":"Party"]
df.loc[[1,2,5],["Year","Candidate"]]
df.loc[:,["Year","Candidate"]]
df.loc[:,"year"] # return series
df.loc[1,"year":"Party"] # return series
df.shape[0] # count of row
df[["Year","Candidate"]][0:5]

type transforming

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df['column_name'] = df['column_name'].astype(int)
df['column_name'] = df['column_name'].astype(float)
df['column_name'] = df['column_name'].astype(str)

Groupby and agg

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df.groupby('column_name').agg(['sum', 'mean', 'max', 'min'])
df.groupby(['column_name_1', 'column_name_2']).agg({'column_name_3': ['sum', 'mean'], 'column_name_4': ['max', 'min']})
df.groupby(['column_name_1', 'column_name_2']).agg(['sum', 'mean', 'max', 'min'])

Example

Example 1

Extracting the top 20 categories from a DataFrame using groupby:

1. Use the groupby and size methods to calculate the size of each group:

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   group_sizes = df.groupby('category').size() ```` 2. Use the `sort_values` method to sort the group sizes in descending order: ```python sorted_groups = group_sizes.sort_values(ascending=False)

2. Use the head method to extract the top 20 categories:

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top_20 = sorted_groups.head(20)

4. Use the isin method to filter the original DataFrame to only include rows with the top 20 categories:

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df_filtered = df[df['category'].isin(top_20.index)]

This will extract the top 20 categories from the ‘category’ column of the DataFrame and create a new DataFrame that only includes rows with those categories.

• Beautiful Soup
  • Generate bs4
  • find node
  • siblings
  • with Regular Expression

Beautiful Soup

Generate bs4

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soup = bs4.BeautifulSoup(text)

find node

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soup.find("div", attrs={"id":"..."})
soup.find_all("...")
soup.div

siblings

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soup.find("...").next_sibling
soup.find("...").previous_sibling
for elm in soup.div.next_siblings:
    ...

with Regular Expression

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soup(class_=re.compile('item-'))
soup(attrs={"class":re.compile("star-rating.*")})[0].get("class")[1]

• Syntax
• Usage
  • Use re
  • Use Pandas
• Example
  • Example 1

s—
id: “regex”
aliases:
- “Usage”
- “Syntax”
tags:
- “regex”
- “python”

Syntax

regex101
regexr

Usage

Use re

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re.sub(pattern,repl,str)
re.search(pattern, str)
re.findall(pattern,str)

Use Pandas

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df['column_name'].str.contains('pattern')
df['column_name'].str.findall('pattern')
df['column_name'].str.replace('pattern', 'replacement')

Example

Example 1

Extracting room numbers from a ‘Description’ column in a DataFrame using regular expressions:

1. Import the re module:

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   import re ```` 2. Define a function to extract the room number from a description: ```python def extract_room_number(description): match = re.search(r'(\d+\.\d+|\d+)(?=\s+of which are bedrooms)', description) if match: return float(match.group(1)) else: return None

2. Use the apply() method to apply the function to the ‘Description’ column and create a new ‘RoomNumber’ column:

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df['RoomNumber'] = df['Description'].apply(extract_room_number)

This will extract the room number from the ‘Description’ column and store it in the new ‘RoomNumber’ column.

Some basic operation

Shuffle the training set for hold out validation

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from sklearn.utils import shuffle
training_set,dev_set = np.split(shuffle(data_sample_35),[25])

Also capable of spliting training set, validation(development) set, test set

Generator file

File Path: catkin_ws/src/test/script/env_pkl_generator.py

Launch Ros

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cd ~
roslaunch test demo_gazebo.launch

It will open Gazebo and RViz and display the robotic arm on both sofware.

Load Scene

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cd ~
rosrun test moveit_setscene.py
rosrun test gazebo_setscene.py

远程链接

向日葵
识别吗
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ge6v9Q

Practicing website

sql-practice

• Environment
• Example

Environment

Install package for sql

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pip install sqlalchemy
pip install ibm_db_sa
pip install ipython-sql

Example

• 如何使用Shader实现语义分割
  • 什么是Shader
  • Shader代码的组成部分
  • 如何使用Shader实现语义分割

如何使用Shader实现语义分割

什么是Shader

Shader是一种计算机程序，它用于在图形渲染管线中处理顶点和像素。在Unity中，Shader可以用来控制物体的渲染方式，包括颜色、纹理、透明度等。Shader的工作流程是将材料（如纹理、数据、颜色等）通过加工展现在材质上的过程。

Unity中有多种类型的Shader，可以根据不同的情况使用。例如，在三维网格上使用的方式和图片上使用的方式会有区别。

Shader代码的组成部分

一个Unity Shader通常由以下几个部分组成：

• Properties：这部分定义了Shader中可供用户在材质检查器中编辑的属性。例如，可以定义一个颜色属性，让用户可以在材质检查器中更改物体的颜色。

• SubShader：每个Shader至少包含一个SubShader。SubShader定义了Shader的实际渲染操作。如果Shader需要支持多种不同的渲染硬件或渲染质量设置，可以在Shader中定义多个SubShader。

• Pass：每个SubShader至少包含一个Pass。Pass定义了一次渲染操作，包括顶点和片段着色器的代码。可以在一个SubShader中定义多个Pass来实现多次渲染操作。

• CGPROGRAM：这部分包含了顶点和片段着色器的代码。可以使用Cg/HLSL语言来编写着色器代码，并使用内置的变量和函数来访问物体的信息。

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  Shader "Custom/SimpleColor" { Properties { _Color ("Color", Color) = (1,1,1,1) } SubShader { Tags { "RenderType"="Opaque" } LOD 100 Pass { CGPROGRAM #pragma vertex vert #pragma fragment frag fixed4 _Color; struct appdata { float4 vertex : POSITION; }; struct v2f { float4 vertex : SV_POSITION; }; v2f vert (appdata v) { v2f o; o.vertex = UnityObjectToClipPos(v.vertex); return o; } fixed4 frag (v2f i) : SV_Target { return _Color; } ENDCG } } }

如何使用Shader实现语义分割

如果希望根据物体的标签来控制物体的颜色，可以在Shader中使用材质属性来实现。首先，需要在脚本中获取物体的标签信息，并根据标签信息设置物体材质的颜色属性。然后，在Shader中，可以使用这个颜色属性来控制物体的渲染颜色。

下面是一个简单的示例，它展示了如何在脚本中设置材质的颜色属性，并在Shader中使用该属性来控制物体的颜色：

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// 脚本中设置材质的颜色属性
void Start()
{
    Renderer renderer = GetComponent<Renderer>();
    Material material = renderer.material;

    // 根据物体的标签设置材质的颜色属性
    if (CompareTag("Pedestrian"))
    {
        material.SetColor("_Color", Color.blue);
    }
    else if (CompareTag("Road"))
    {
        material.SetColor("_Color", Color.white);
    }
    else if (CompareTag("Building"))
    {
        material.SetColor("_Color", Color.black);
    }
}
````

```c
// Shader中使用颜色属性来控制物体的颜色
Shader "Custom/SemanticSegmentation" {
    Properties {
        _Color ("Color", Color) = (1,1,1,1)
    }
    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            fixed4 _Color;

            struct appdata {
                float4 vertex : POSITION;
            };

            struct v2f {
                float4 vertex : SV_POSITION;
            };

            v2f vert (appdata v) {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target {
                return _Color;
            }
            ENDCG
        }
    }
}