数据框中的列自动转换为浮点类型

Question

我有这样的数据框

当我像这样应用函数时 中位数= Top15 [＆＃39;％可再生＆＃39;]。中位数（轴= 0）

def func(Top15):
    if (Top15['% Renewable'] >= median):
        Top15['HighRenew'] = 1
    else:
        Top15['HighRenew'] = 0
    return Top15
Top15.apply(func,axis=1)

Rank列转换为float，我不知道它为什么

Answer 1

首先我无法模拟你的问题。

我认为更好的是与布尔掩码相比较，并将int True转换为1 False和0转换为Top15['Rank'] = (Top15['% Renewable'] >= Top15['% Renewable'].median(axis=0)).astype(int) ：< / p>

apply

避免Top15 = pd.DataFrame({'% Renewable':[10,23,56,78,90], 'Rank':[10,20,30,4,50]}) print (Top15) #Top15 = pd.concat([Top15] * 1000, ignore_index=True) % Renewable Rank 0 10 10 1 23 20 2 56 30 3 78 4 4 90 50 median = Top15['% Renewable'].median(axis=0) def func(x): if (x['% Renewable'] >= median): x['HighRenew'] = 1 else: x['HighRenew'] = 0 return x Top15 = Top15.apply(func,axis=1) Top15['Rank2'] = (Top15['% Renewable'] >= Top15['% Renewable'].median(axis=0)).astype(int) print (Top15) % Renewable Rank HighRenew Rank2 0 10 10 0 0 1 23 20 0 0 2 56 30 1 1 3 78 4 1 1 4 90 50 1 1 （如果可能）的主要原因是引擎盖下的循环。

<强>示例：

Top15 = pd.DataFrame({'% Renewable':[10,23,56,78,90],
                      'Rank':[10,20,30,4,50]})
print (Top15)
Top15 = pd.concat([Top15] * 1000, ignore_index=True)

In [49]: %timeit Top15.apply(func,axis=1)
1 loop, best of 3: 595 ms per loop

In [50]: %timeit (Top15['% Renewable'] >= Top15['% Renewable'].median(axis=0)).astype(int)
The slowest run took 5.19 times longer than the fastest. This could mean that an intermediate result is being cached.
1000 loops, best of 3: 346 µs per loop

<强>计时：

public static void sendResponse (InputStream inputData, String fileName, HttpServletResponse res) 
        throws IOException {

    try {

        String contenttype = new ConfigurableMimeFileTypeMap().getContentType(fileName);

        res.reset();
        res.setContentType(contenttype);
        res.addHeader("Content-Disposition", String.format("attachment;filename=\"%s\"", name));                
        ByteStreams.copy(inputData, res.getOutputStream());

    } catch (Exception e) {
        throw new IOException(e);
    } 
}

Answer 2

你可以使用astype TOP15 [ '等级'] = Top15.Rank.astype（int）的 要么 TOP15 [ '等级'] = Top15.Rank.astype（对象）