小编b_p*_*kes的帖子

How can I add a custom hyperlink field in a serializer? I would like to have a hyperlink field in my serializer that has query params in it. Since there is no way to pass query params from HyperlinkedRelatedField or HyperlinkedIdentityField as far as I know, I've tried using a SerializerMethodField. However, this only serializes to a string, and is not a clickable URL when I visit the API through my browser. My code looks something like this:

class …

我正在尝试运行示例hadoop-streaming命令:

hadoop-streaming -files streamingCode/wordSplitter.py \
-mapper wordSplitter.py \
-input s3://elasticmapreduce/samples/wordcount/input \
-output streamingCode/wordCountOut \
-reducer aggregate

但我一直收到这个错误:

Exception in thread "main" com.amazon.ws.emr.hadoop.fs.shaded.com.amazonaws.services.s3.model.AmazonS3Exception: Moved Permanently (Service: Amazon S3; Status Code: 301; Error Code: 301 Moved Permanently; Request ID: 98038E504E150CEC), S3 Extended Request ID: IW1x5otBSepAnPgW/RKELCUI9dhADQvrXqU2Ase1CLIa0SWDFnBbTscXihrvHvNm2ZRxjjSJZ1Q=

我认为这是因为我的群集在us-west-2,但我无法弄清楚如何正确格式化s3网址(或者根本不是问题).

编辑:将其更改为以下网址后:

s3://s3-us-west-2.amazonaws.com/elasticmapreduce/samples/wordcount/input

我现在收到以下错误:

Exception in thread "main" com.amazon.ws.emr.hadoop.fs.shaded.com.amazonaws.services.s3.model.AmazonS3
Exception: Access Denied (Service: Amazon S3; Status Code: 403; Error Code: AccessDenied; Request ID: BC8DB415C780DF84), 
           S3 Extended Request ID: sx8W/+gvND2ssqQce9ZQsZTiqxmSJYZs8OiXgrjwL3dm0JRPaC7ceHor+yrHsPuKTjM2LUwkRAw=

编辑:所以我已经确认错误确实是因为我的群集在us-west-2,我已经创建了一个群集us-east-1 …

我正在尝试使用网格搜索来确定在PCA中使用的n_components的最佳值:

from sklearn.decomposition import PCA
from sklearn.grid_search import GridSearchCV
from sklearn.pipeline import Pipeline
from sklearn.preprocessing import StandardScaler
from sklearn.linear_model import LinearRegression


pca = PCA()
pipe_lr = Pipeline([('pca', pca),
                    ('regr', LinearRegression())])

param_grid = [{'pca__n_components': range(2, X.shape[1])}]

gs = GridSearchCV(estimator=pipe_lr, 
                  param_grid=param_grid, 
                  cv=3)
gs = gs.fit(X_train, y_train)
print(gs.best_score_)
print(gs.best_params_)

for i in range(2, X.shape[1]):
    pca.n_components = i
    pipe_lr = pipe_lr.fit(X_train, y_train)
    print i, pipe_lr.score(X_test, y_test)

但是,我看到的结果非常奇怪(我从for循环获得的数字与网格搜索中的数字完全不同):

-0.232877626581
{'pca__n_components': 2}
2 0.0989156092429
3 0.258170750388
4 0.26328990417
5 0.263620889601
6 0.315725901097
7 0.315477694958
8 0.330445632512 …

我知道如果我传递一个类似于void (*func)(void *)可变函数的参数,我可以检索如下的参数:

void (*func)(void *) = va_arg( args, void (*)(void) );

如果我传递类似的内容void (** func)(void *)怎么办？使用va_arg？检索此类型的参数的正确语法是什么？

我在Python中遇到了gcd的这个实现:

def gcd(x,y): return y and gcd(y, x % y) or x

我不明白的是布尔值在返回时是如何工作的？在解释器中尝试了一些数字后,我注意到and总是返回右边or的数字,而返回左边的数字.为什么是这样？另外,您可以一步一步地通过简单调用此函数来指导我,以便了解发生了什么？

如果我有这样的代码块：

try:
    if 45 = 45 : print 45
except SyntaxError:
    print "stuff"

当我运行它时，我仍然得到一个SyntaxError. 但是，如果我这样做：

try:
    raise SyntaxError
except SyntaxError:
    print "stuff"

然后它按预期工作（即打印“东西”）。有可能抓住吗SyntaxError？