我想知道它们之间有什么区别：
with codecs.open('xxxx.csv', 'rU') as h:
和
with codecs.open('xxxx.csv', 'rb') as h:
我想我记得有人说你应该使用＆＃39; rb ＆＃39;而不是＆＃39; rU ＆＃39;当我开始阅读.csv文件的项目时，我似乎无法再找到它。
有人想解释一下吗？ 感谢
答案 0 :(得分：8)
作为the documentation状态，不推荐使用 /**
* Since every observable into the zip is created to subscribeOn a diferent thread, it´s means all of them will run in parallel.
* By default Rx is not async, only if you explicitly use subscribeOn.
*/
@Test
public void testAsyncZip() {
scheduler = Schedulers.newThread();
scheduler1 = Schedulers.newThread();
scheduler2 = Schedulers.newThread();
long start = System.currentTimeMillis();
Observable.zip(obAsyncString(), obAsyncString1(), obAsyncString2(), (s, s2, s3) -> s.concat(s2)
.concat(s3))
.subscribe(result -> showResult("Async in:", start, result));
}
/**
* In this example the the three observables will be emitted sequentially and the three items will be passed to the pipeline
*/
@Test
public void testZip() {
long start = System.currentTimeMillis();
Observable.zip(obString(), obString1(), obString2(), (s, s2, s3) -> s.concat(s2)
.concat(s3))
.subscribe(result -> showResult("Sync in:", start, result));
}
public void showResult(String transactionType, long start, String result) {
System.out.println(result + " " +
transactionType + String.valueOf(System.currentTimeMillis() - start));
}
public Observable<String> obString() {
return Observable.just("")
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> "Hello");
}
public Observable<String> obString1() {
return Observable.just("")
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> " World");
}
public Observable<String> obString2() {
return Observable.just("")
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> "!");
}
public Observable<String> obAsyncString() {
return Observable.just("")
.observeOn(scheduler)
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> "Hello");
}
public Observable<String> obAsyncString1() {
return Observable.just("")
.observeOn(scheduler1)
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> " World");
}
public Observable<String> obAsyncString2() {
return Observable.just("")
.observeOn(scheduler2)
.doOnNext(val -> {
System.out.println("Thread " + Thread.currentThread()
.getName());
})
.map(val -> "!");
}
（通用换行符）模式;你不应该再使用它了。而是使用U关键字参数。
The csv documentation声明它更喜欢该参数为newline=，因此''不会对换行符进行任何解释，并将其留给open模块。< / p>
由于您可能希望将CSV解码为 text （而非字节），因此在csv（二进制）模式下打开它们毫无意义。
底线：解析CSV文件的常用方法是：
b这意味着您正在使用隐式with open('eggs.csv', newline='') as csvfile:
spamreader = csv.reader(csvfile)
for row in spamreader:
...
模式open，以便在文本模式下阅读。除非你有非常特殊的需求，否则这可能就是你想要的。以上示例代码直接来自文档。