如何替换熊猫数据框中的值？

Question

我想用“空”这个词代替问号。我该怎么做？ （这是熊猫数据框） {]1

 import pandas as pd
df = pd.read_csv(r'C:\Users\ASUS\Downloads\bridges.csv' , header=None)
df.columns = ["IDENTIF", "RIVER", "LOCATION", "ERECTED","PURPOSE", "LENGTH", "LANES", "CLEAR-G","T-OR-D", "MATERIAL", "SPAN", "REL-L","TYPE"]
print(df)

Answer 1

试试

import numpy as np    
df = df.replace('?', np.nan)

或者，您可能真的想使用：

#include "Event.h"

Event::Event(const std::function<void()>& cb)
    : methodTobeCalled(cb)
{
}

HRESULT Event::NetworkConnectionConnectivityChanged(GUID, NLM_CONNECTIVITY)
{
    if (methodTobeCalled)
        methodTobeCalled();

    return S_OK;
}

HRESULT Event::NetworkConnectionPropertyChanged(GUID, NLM_CONNECTION_PROPERTY_CHANGE)
{
    return S_OK;
}

STDMETHODIMP Event::QueryInterface(REFIID refIID, void** pIFace)
{
    HRESULT hr = S_OK;
    *pIFace = nullptr;
    if (IsEqualIID(refIID, IID_IUnknown))
    {
        *pIFace = (IUnknown *)this;
        ((IUnknown *)*pIFace)->AddRef();
    }
    else if (IsEqualIID(refIID, IID_INetworkConnectionEvents))
    {
        *pIFace = (INetworkConnectionEvents *)this;
        ((IUnknown *)*pIFace)->AddRef();
    }
    else
    {
        hr = E_NOINTERFACE;
    }

    return hr;
}

ULONG Event::AddRef(void)
{
    return static_cast<ULONG>(InterlockedIncrement(&m_ref));
}

ULONG Event::Release(void)
{
    LONG Result = InterlockedDecrement(&m_ref);
    return static_cast<ULONG>(Result);
}