Question

我确定我犯了一个明显的错误，但看不到它。

我的df看起来像这样：

id year plan grade prior_grade
21 2017 text A     B
56 2015 text B     B
43 2016 text A     C

并且想要创建一个新的df，只包含那些previous_grade = c的行。我正在使用它来这样做：

prior_c = (df.loc[(df['prior_grade']=='C')])

返回一个空的df（列名称打印但在调用prior_c.head()时没有行）

再一次，我确定我犯了一个明显的错误，但却看不到它。

编辑：尝试用少量的parens并得到相同的结果：

prior_c = df.loc[df['prior_grade']=='C']

Answer 1

这应该可行，但我相信你应该复制数据帧。这用于明确地使新数据帧成为副本（而不是原始视图），以避免无意中更改原始df。我建议如下：

<body style="background-color: White"> <form id="form1" runat="server"> <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager> <div> <ul class="topnav"> <li> <img src="https://cync.cinergycinemas.com/Images/Logo-15.png" alt="Logo" /> </li> <li><a href="Adminhome.aspx">Home</a></li> <li> <a class="active" href="timecontrol.aspx">Employees<br /> <asp:Label ID="lbltotalemp" runat="server" Font-Bold="True"></asp:Label> </a> </li> <li> <a href="clockedIN.aspx">Clocked IN<br /> <asp:Label ID="lblin" runat="server" Font-Bold="True"></asp:Label> </a> </li> <li> <a href="Overtimegv.aspx">Overtime<br /> <asp:Label ID="lblot" runat="server" Font-Bold="True"></asp:Label> </a> </li> <li class="right"><a href="EID2.aspx">Sign out</a></li> </ul> </div> <%-- Search box autocomplete extender using ajax --%> <br /> <br /> <br /> <div style="margin: 50px; text-align: center"> <asp:TextBox ID="txtSearch" runat="server"></asp:TextBox> <ajaxToolkit:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" ServiceMethod="SearchCustomers" MinimumPrefixLength="1" CompletionInterval="100" EnableCaching="false" CompletionSetCount="0" TargetControlID="txtSearch" FirstRowSelected="True" CompletionListCssClass="AutoExtender" CompletionListItemCssClass="AutoExtenderList" CompletionListHighlightedItemCssClass="AutoExtenderHighlight" CompletionListElementID="divwidth"> </ajaxToolkit:AutoCompleteExtender> <asp:Button ID="btnSearch" runat="server" Text="Search" /><br /> <br /> <%-- <input type="checkbox" id="Virtual_Keyboard" />Use Virtual Keyboard<br />--%> <%-- Gridview 1--%> <asp:GridView ID="MainGV" runat="server" AutoGenerateColumns="False" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt" DataKeyNames="EID" HorizontalAlign="Center" EmptyDataText="No Data Found. Try Again !" AllowPaging="True" Font-Bold="True" ForeColor="Black" AllowSorting="True" OnRowDataBound="MainGV_RowDataBound"> <AlternatingRowStyle CssClass="alt"></AlternatingRowStyle> <Columns> <asp:TemplateField><%--Plus and minus buttons--%> <ItemTemplate> <img src="images/plus.png" style="cursor: pointer" /> <asp:Panel ID="Panel1" runat="server" Style="display: none"> <%--Style="display: none"--%> <asp:GridView ID="childGV" runat="server" AutoGenerateColumns="False" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt" DataKeyNames="EID" HorizontalAlign="Center" EmptyDataText="No Data / Approved !" AllowPaging="True" Font-Bold="True" ForeColor="Black"> <AlternatingRowStyle CssClass="alt" /> <Columns> <asp:TemplateField> <HeaderTemplate> <asp:CheckBox runat="server" ID="chkCheckall" onclick="checkAll(this)" AutoPostBack="True"></asp:CheckBox> </HeaderTemplate> <ItemTemplate> <asp:CheckBox runat="server" ID="chkCheck" onclick="Check_Click(this)" AutoPostBack="True" OnCheckedChanged="chkCheck_CheckedChanged"></asp:CheckBox> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="ID" HeaderText="ID" ReadOnly="True" InsertVisible="False" SortExpression="ID" Visible="false"></asp:BoundField> <asp:BoundField DataField="EID" HeaderText="EID" ReadOnly="True" SortExpression="EID" Visible="false"></asp:BoundField> <asp:BoundField DataField="FirstName" HeaderText="FirstName" SortExpression="FirstName" Visible="false"></asp:BoundField> <asp:BoundField DataField="LastName" HeaderText="LastName" SortExpression="LastName" Visible="false"></asp:BoundField> <asp:BoundField DataField="Gender" HeaderText="Gender" SortExpression="Gender" Visible="false"></asp:BoundField> <asp:BoundField DataField="Department" HeaderText="Department" SortExpression="Department" Visible="false"></asp:BoundField> <asp:BoundField DataField="JobFunctionalTitle" HeaderText="JobFunctionalTitle" SortExpression="JobFunctionalTitle" Visible="false"></asp:BoundField> <asp:BoundField DataField="IN_Time" HeaderText="IN_Time" ReadOnly="True" SortExpression="IN_Time"></asp:BoundField> <asp:BoundField DataField="OUT_Time" HeaderText="OUT_Time" ReadOnly="True" SortExpression="OUT_Time"></asp:BoundField> <asp:BoundField DataField="Department1" HeaderText="Department1" SortExpression="Department1"></asp:BoundField> <asp:BoundField DataField="Hours2" HeaderText="Hours2" SortExpression="Hours2"></asp:BoundField> <asp:BoundField DataField="Notes" HeaderText="Notes" SortExpression="Notes"></asp:BoundField> </Columns> <PagerStyle CssClass="pgr" /> </asp:GridView> </asp:Panel> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="EID" SortExpression="EID"> <%--<EditItemTemplate> <asp:Label runat="server" Text='<%# Eval("EID") %>' ID="Label1"></asp:Label> </EditItemTemplate>--%> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("EID") %>' ID="Label1"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="FullName" SortExpression="FullName"> <EditItemTemplate> <asp:Label runat="server" Text='<%# Eval("FullName") %>' ID="Label2"></asp:Label> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("FullName") %>' ID="Label2"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Gender" SortExpression="Gender"> <EditItemTemplate> <asp:TextBox runat="server" Text='<%# Bind("Gender") %>' ID="TextBox1"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("Gender") %>' ID="Label3"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Department" SortExpression="Department"> <EditItemTemplate> <asp:TextBox runat="server" Text='<%# Bind("Department") %>' ID="TextBox2"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("Department") %>' ID="Label4"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="JobFunctionalTitle" SortExpression="JobFunctionalTitle"> <EditItemTemplate> <asp:TextBox runat="server" Text='<%# Bind("JobFunctionalTitle") %>' ID="TextBox3"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("JobFunctionalTitle") %>' ID="Label5"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Location" SortExpression="Location"> <EditItemTemplate> <asp:TextBox runat="server" Text='<%# Bind("Location") %>' ID="TextBox4"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("Location") %>' ID="Label6"></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Location_Name" SortExpression="Location_Name" Visible="false"> <EditItemTemplate> <asp:TextBox runat="server" Text='<%# Bind("Location_Name") %>' ID="TextBox5"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label runat="server" Text='<%# Bind("Location_Name") %>' ID="Label7"></asp:Label> </ItemTemplate> </asp:TemplateField> </Columns> <PagerStyle CssClass="pgr"></PagerStyle> </asp:GridView> </div> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:dev_prashanthConnectionString %>" SelectCommand="Sp_timedeptdisplaytest1" SelectCommandType="StoredProcedure"> <SelectParameters> <asp:ControlParameter ControlID="HFLocnum" Name="Locnum" PropertyName="Value" Type="String" DefaultValue=""></asp:ControlParameter> <asp:ControlParameter ControlID="txtSearch" PropertyName="Text" DefaultValue="NULL" Name="SearchText" Type="String"></asp:ControlParameter> </SelectParameters> </asp:SqlDataSource> <%--<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString='<%$ ConnectionStrings:DWHConnectionString %>' SelectCommand="SELECT * FROM [tbl_EID_PIN]"></asp:SqlDataSource>--%> <asp:HiddenField ID="HFclkincount" runat="server" /> <asp:HiddenField ID="HFtotalcount" runat="server" /> <asp:HiddenField ID="HFLocnum" runat="server" /> <asp:HiddenField ID="HFhours2" runat="server" /> <script> function CreatePopup() { return confirm("Do you confirm?"); } </script> <asp:HiddenField ID="HFEID" runat="server" /> </form> </body>

pandas df.loc返回空白df

1 个答案: