我有一个包含4列的pandas数据帧df。例如，这是一个玩具示例：
foo1 foo2 foo3 foo4
egg cheese 2 1
apple pear 1 3
french spanish 10 1
列是foo1，foo2，foo3和foo4
我想交换列foo1和foo2，并且当foo3＆lt; foo3和foo4时交换列foo3和foo4。 foo4。结果将是：
foo1 foo2 foo3 foo4
cheese egg 1 2
apple pear 1 3
spanish french 1 10
我可以找到需要与df[df['foo3'] < df['foo4']]交换的行，但是如何有效地进行交换。我的数据框很大。
答案 0 :(得分：3)
您可以找到void Start()
{
InitCognito ();
}
public void InitCognito()
{
UnityInitializer.AttachToGameObject (this.gameObject);
credentials = new CognitoAWSCredentials (
identity_pool_id, // Identity Pool ID
region // Region
);
Debug.Log ("identity_pool_id = " + identity_pool_id + " region = " + region);
credentials.GetIdentityIdAsync(delegate(AmazonCognitoIdentityResult<string>
result) {
if (result.Exception != null) {
Debug.LogError(result.Exception.ToString());
}
string identityId = result.Response;
Debug.Log("identityId = "+identityId);
FBInit();
});
}
public void FBInit()
{
FB.Init(this.OnInitComplete, this.OnHideUnity);
Debug.Log( "FB.Init() called with " + FB.AppId);
}
public void FBLogin()
{
FB.LogInWithReadPermissions(new List<string>() { "public_profile", "email", "user_friends" }, this.HandleResult);
}
private void OnInitComplete()
{
Debug.Log( "Success - Check log for details");
Debug.Log("Success Response: OnInitComplete Called\n");
Debug.Log( string.Format(
"OnInitCompleteCalled IsLoggedIn='{0}' IsInitialized='{1}'",
FB.IsLoggedIn,
FB.IsInitialized));
if (AccessToken.CurrentAccessToken != null)
{
Debug.Log("Access token = "+AccessToken.CurrentAccessToken.ToString());
}
FBLogin ();
}
private void OnHideUnity(bool isGameShown)
{
Debug.Log( "Success - Check log for details");
Debug.Log(string.Format("Success Response: OnHideUnity Called {0}\n", isGameShown));
Debug.Log("Is game shown: " + isGameShown);
}
protected void HandleResult(IResult result)
{
if (result == null)
{
Debug.Log("Null Response\n");
return;
}
// Some platforms return the empty string instead of null.
if (!string.IsNullOrEmpty(result.Error))
{
Debug.Log( "Error - Check log for details");
Debug.Log( "Error Response:\n" + result.Error);
}
else if (result.Cancelled)
{
Debug.Log ("Cancelled - Check log for details");
Debug.Log( "Cancelled Response:\n" + result.RawResult);
}
else if (!string.IsNullOrEmpty(result.RawResult))
{
Debug.Log ("Success - Check log for details");
Debug.Log ("Success Response:\n" + result.RawResult);
Debug.Log ("Access Token = "+AccessToken.CurrentAccessToken);
Debug.Log ("Access Token = "+AccessToken.CurrentAccessToken.TokenString);
Debug.Log ("Access User Id =" + AccessToken.CurrentAccessToken.UserId);
credentials.AddLogin ("graph.facebook.com", AccessToken.CurrentAccessToken.TokenString);
if (credentials.CurrentLoginProviders.Length > 0) {
Debug.Log (credentials.CurrentLoginProviders[0]);
}
Debug.Log (credentials.GetCachedIdentityId());
}
else
{
Debug.Log ( "Empty Response\n");
}
}
行，是的，但是如果您使用布尔系列，则可以轻松实现目标：
df[df['foo3'] < df['foo4']]注意，您需要RHS末尾的s = df['foo3'] < df['foo4']
df.loc[s, ['foo1','foo2']] = df.loc[s, ['foo2','foo1']].values
df.loc[s, ['foo3','foo4']] = df.loc[s, ['foo4','foo3']].values
以防止Pandas对齐列名，这会破坏目的。
答案 1 :(得分：1)
您可以使用pandas.Series.where函数根据条件构建新数据框：
pairs = [('foo1', 'foo2'), ('foo3', 'foo4')] # construct pairs of columns that need to swapped
df_out = pd.DataFrame()
# for each pair, swap the values if foo3 < foo4
for l, r in pairs:
df_out[l] = df[l].where(df.foo3 < df.foo4, df[r])
df_out[r] = df[r].where(df.foo3 < df.foo4, df[l])
df_out
# foo1 foo2 foo3 foo4
#0 cheese egg 1 2
#1 apple pear 1 3
#2 spanish french 1 10