Zhentiw - 博客园

2020年9月1日

[React] Manipulate the DOM with React refs

摘要： React is really good at creating and updating DOM elements, but sometimes you need to work with them yourself. A common use case for this is when you’ 阅读全文

posted @ 2020-09-01 19:05 Zhentiw 阅读(173) 评论(0) 推荐(0)

[React] Use a lazy initializer with useState

摘要： Something that’s important to recognize is that every time you call the state updater function (like the setName function in our component), that will 阅读全文

posted @ 2020-09-01 18:54 Zhentiw 阅读(157) 评论(0) 推荐(0)

[React] Implement a Higher Order Component

摘要： Sometimes you have some boilerplate for components that would be nice to abstract away slightly with a simple helper function. In this lesson we'll le 阅读全文

posted @ 2020-09-01 15:30 Zhentiw 阅读(156) 评论(0) 推荐(0)

[React] Returning null from setState in React 16

摘要： Returning null will not update state and trigger a component re-render Example: updateMocktail = mocktail => { const newMocktail = mocktail; this.setS 阅读全文

posted @ 2020-09-01 15:10 Zhentiw 阅读(184) 评论(0) 推荐(0)

2020年8月31日

[Prostgres] Select Grouped and Aggregated Data with SQL

摘要： Another powerful SQL skill is understanding how to group rows together by column values. Once the data is grouped together, it can be difficult to und 阅读全文

posted @ 2020-08-31 23:53 Zhentiw 阅读(137) 评论(0) 推荐(0)

[Machine Learning] Regularization Ex

摘要： If lamda is large then theta should be small in order to minize the cost function. Too large lamda, cause underfitting the data. 阅读全文

posted @ 2020-08-31 02:10 Zhentiw 阅读(161) 评论(0) 推荐(0)

[Machine Learning] Solve overfitting, Regularization

摘要： If we have overfitting from our hypothesis function, we can reduce the weight that some of the terms in our function carry by increasing their cost. S 阅读全文

posted @ 2020-08-31 01:48 Zhentiw 阅读(229) 评论(0) 推荐(0)

[Machine Learning] Logistic Regression Ex

摘要：阅读全文

posted @ 2020-08-31 01:33 Zhentiw 阅读(97) 评论(0) 推荐(0)

2020年8月28日

[Postgres] Keep Data Integrity with Constraints

摘要： If the data in your tables do not have integrity, meaning there are missing rows, incorrect values, or duplicate rows, your table is not worth much. D 阅读全文

posted @ 2020-08-28 19:30 Zhentiw 阅读(169) 评论(0) 推荐(0)

[Postgres] Removing Data with SQL Delete, Truncate, and Drop

摘要： Delete: delete from Users where last_name = 'clark'; If you wanted to delete everything in our table, I mentioned you could just use the delete comman 阅读全文

posted @ 2020-08-28 19:22 Zhentiw 阅读(164) 评论(0) 推荐(0)

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