我从一个XML文件中提取数据，并在每行的两列中显示变量名及其值。因此，每行有两列：每一列具有变量名及其值。我从名为leaf_default.xml的XML文件中获取变量名和值。XML中的一些变量具有孙子节点。我提供的图像显示了一些孙辈节点，它们是d13c、solver_min、a、theta_j等。example of grandchild nodes being displayed如果您查看XML文件，您会注意到reftemp、atref、Ha、Hd、Topt、deltaS、a_deltaS_t、b_deltaS_t、c_deltaS_t等变量都有孙辈节点。
我希望到目前为止我所解释的是有意义的。我想做的是创建一行和两列，在一列中显示变量和孙子节点的值。example of what I'd like to achieve

Here's the xml file:
<default>
  <fnames>
    <leaf>
      <sys>'f_sys_enzymek'</sys>
      <rh_or_vpd>'f_vpd_from_rh'</rh_or_vpd>
      <sat_vp>'f_sat_vp_allen1998'</sat_vp>
      <solver>'f_solver_brent'</solver>
      <residual_func>'f_residual_func_leaf_Ar'</residual_func>
      <assimilation>'f_assimilation_c3'</assimilation>
      <photorespiration>'f_photorespiration_f1980'</photorespiration>
      <semiana>'f_semiana_quad'</semiana>
      <Acg>'f_Acg_farquhar1980'</Acg>
      <Ajg>'f_Ajg_generic'</Ajg>
      <Apg>'f_Apg_vonc2000'</Apg>
      <etrans>'f_etrans_harley1992'</etrans>
      <gas_diff>'f_gas_diff_ficks_ci'</gas_diff>
      <Alim>'f_Alim_farquhar1980'</Alim>
      <vcmax>'f_vcmax_lin'</vcmax>
      <jmax>'f_jmax_power'</jmax>
      <tcor_jmax>'f_scalar_none'</tcor_jmax>
      <tpu>'f_tpu_lin'</tpu>
      <k_pepc>'f_k_pepc_constant'</k_pepc>
      <rd>'f_rd_lin_vcmax'</rd>
      <rl_rd>'f_scalar_none'</rl_rd>
      <gstar>'f_gstar_f1980'</gstar>
      <ri>'f_r_zero'</ri>
      <rs>'f_rs_medlyn2011'</rs>
      <rb>'f_rb_leafdim'</rb>
      <cica_ratio>'f_cica_ratio_constant'</cica_ratio>
      <d13c>'f_d13c_classical'</d13c>
      <tcor_asc>
        <vcmax>'f_tcor_asc_Arrhenius'</vcmax>
        <jmax>'f_tcor_asc_Arrhenius'</jmax>
        <tpu>'f_tcor_asc_Arrhenius'</tpu>
        <k_pepc>'f_tcor_asc_Arrhenius'</k_pepc>
        <rd>'f_tcor_asc_Arrhenius'</rd>
        <gstar>'f_tcor_asc_quadratic_bf1985'</gstar>
        <tau>'f_tcor_asc_Q10'</tau>
        <Kc>'f_tcor_asc_Arrhenius'</Kc>
        <Ko>'f_tcor_asc_Arrhenius'</Ko>
      </tcor_asc>
      <tcor_des>
        <vcmax>'f_tcor_des_modArrhenius'</vcmax>
        <jmax>'f_tcor_des_modArrhenius'</jmax>
        <tpu>'f_tcor_des_modArrhenius'</tpu>
        <k_pepc>'f_tcor_des_modArrhenius'</k_pepc>
        <rd>'f_scalar_none'</rd>
      </tcor_des>
      <tcor_dep>
        <tpu>'f_tcor_dep_independent'</tpu>
        <rd>'f_tcor_dep_independent'</rd>
        <tau>'f_tcor_dep_independent'</tau>
      </tcor_dep>
      <deltaS>
        <rd>'f_deltaS'</rd>
        <vcmax>'f_deltaS'</vcmax>
        <jmax>'f_deltaS'</jmax>
        <tpu>'f_deltaS'</tpu>
        <k_pepc>'f_deltaS'</k_pepc>
      </deltaS>
      <q10>
        <rd>'f_q10_constant'</rd>
        <vcmax>'f_q10_constant'</vcmax>
        <jmax>'f_q10_constant'</jmax>
        <k_pepc>'f_q10_constant'</k_pepc>
        <tau>'f_q10_constant'</tau>
        <Kc>'f_q10_constant'</Kc>
        <Ko>'f_q10_constant'</Ko>
      </q10>
    </leaf>
  </fnames>
  <pars>
    <leaf>
      <d13c>FALSE</d13c>
      <deltaA_prop>0.15</deltaA_prop>
      <solver_min>-0.0029834</solver_min>
      <solver_max>51.8364435</solver_max>
      <a>0.8</a>
      <f>0.23</f>
      <quantum_yield_to_eff>4</quantum_yield_to_eff>
      <ko_kc_ratio>0.21</ko_kc_ratio>
      <theta_j>0.9</theta_j>
      <theta_col_cj>0.95</theta_col_cj>
      <theta_col_cjp>0.98</theta_col_cjp>
      <avn_25>10</avn_25>
      <bvn_25>30</bvn_25>
      <ajv_25>29</ajv_25>
      <bjv_25>1.63</bjv_25>
      <a_jvt_25>2.59</a_jvt_25>
      <b_jvt_25>-0.035</b_jvt_25>
      <c_jvt_25>-0.0202</c_jvt_25>
      <e_ajv_25>1.01</e_ajv_25>
      <e_bjv_25>0.89</e_bjv_25>
      <atv_25>0</atv_25>
      <btv_25>0.166666666666667</btv_25>
      <akv_25>0</akv_25>
      <bkv_25>20000</bkv_25>
      <flnr>0.09</flnr>
      <fnr>7.16</fnr>
      <Rsa>60</Rsa>
      <Apg_alpha>0</Apg_alpha>
      <g0>0.01</g0>
      <g1_medlyn>4.16</g1_medlyn>
      <g1_leuning>10</g1_leuning>
      <d0>1</d0>
      <g1_ball>6</g1_ball>
      <g_a1_yin>0.85</g_a1_yin>
      <g_b1_yin>0.14</g_b1_yin>
      <rs>6.66666666666667</rs>
      <cica_chi>0.7</cica_chi>
      <rb>0.1</rb>
      <can_ttc>0.01</can_ttc>
      <leaf_width>0.1</leaf_width>
      <ri>6.66666666666667</ri>
      <co2_diff>1.7e-09</co2_diff>
      <hco_co2_ratio>0</hco_co2_ratio>
      <hco_co2_diff_ratio>0.56</hco_co2_diff_ratio>
      <d13c_a>4.4</d13c_a>
      <d13c_b>27</d13c_b>
      <d13c_b_prime>30</d13c_b_prime>
      <d13c_am>1.8</d13c_am>
      <d13c_f>12</d13c_f>
      <a_rdv_25>0</a_rdv_25>
      <b_rdv_25>0.015</b_rdv_25>
      <a_rdn_25>0.5</a_rdn_25>
      <b_rdn_25>0.15</b_rdn_25>
      <rl_rd_ratio>1</rl_rd_ratio>
      <rl_rd_lloyd_a>0.5</rl_rd_lloyd_a>
      <rl_rd_lloyd_b>0.05</rl_rd_lloyd_b>
      <a_rdv_25_t>0.015</a_rdv_25_t>
      <b_rdv_25_t>-5e-04</b_rdv_25_t>
      <home_temp>25</home_temp>
      <reftemp>
        <rd>25</rd>
        <vcmax>25</vcmax>
        <jmax>25</jmax>
        <tpu>25</tpu>
        <k_pepc>25</k_pepc>
        <Kc>25</Kc>
        <Ko>25</Ko>
        <gstar>25</gstar>
        <tau>25</tau>
      </reftemp>
      <atref>
        <rd>2</rd>
        <vcmax>50</vcmax>
        <jmax>100</jmax>
        <tpu>5</tpu>
        <k_pepc>7e+05</k_pepc>
        <Kc>40.49</Kc>
        <Ko>27.84</Ko>
        <gstar>4.325</gstar>
        <tau>2.6</tau>
        <vomax>0</vomax>
      </atref>
      <Ha>
        <rd>69830</rd>
        <vcmax>69830</vcmax>
        <jmax>100280</jmax>
        <tpu>69830</tpu>
        <k_pepc>69830</k_pepc>
        <Kc>79430</Kc>
        <Ko>36380</Ko>
        <gstar>37830</gstar>
        <tau>-41572</tau>
        <vomax>60110</vomax>
      </Ha>
      <Hd>
        <rd>2e+05</rd>
        <vcmax>2e+05</vcmax>
        <jmax>2e+05</jmax>
        <tpu>2e+05</tpu>
        <k_pepc>2e+05</k_pepc>
      </Hd>
      <Topt>
        <rd>27.56</rd>
        <vcmax>27.56</vcmax>
        <jmax>19.89</jmax>
        <tpu>27.56</tpu>
        <k_pepc>27.56</k_pepc>
      </Topt>
      <deltaS>
        <rd>0</rd>
        <vcmax>0</vcmax>
        <jmax>0</jmax>
        <tpu>0</tpu>
        <k_pepc>0</k_pepc>
      </deltaS>
      <a_deltaS_t>
        <rd>490</rd>
        <vcmax>668</vcmax>
        <jmax>660</jmax>
        <tpu>485</tpu>
      </a_deltaS_t>
      <b_deltaS_t>
        <rd>0</rd>
        <vcmax>-1.07</vcmax>
        <jmax>-0.75</jmax>
        <tpu>0</tpu>
      </b_deltaS_t>
      <c_deltaS_t>
        <rd>0</rd>
        <vcmax>0</vcmax>
        <jmax>-0.52</jmax>
        <tpu>0</tpu>
      </c_deltaS_t>
      <q10>
        <rd>2</rd>
        <vcmax>2</vcmax>
        <jmax>2</jmax>
        <tpu>2</tpu>
        <k_pepc>2</k_pepc>
        <Kc>2</Kc>
        <Ko>2</Ko>
        <tau>0.57</tau>
      </q10>
      <a_q10_t>
        <rd>3.22</rd>
      </a_q10_t>
      <b_q10_t>
        <rd>-0.046</rd>
      </b_q10_t>
      <tupp_cox>
        <vcmax>36</vcmax>
        <rd>45</rd>
      </tupp_cox>
      <tlow_cox>
        <vcmax>0</vcmax>
        <rd>5</rd>
      </tlow_cox>
      <exp_cox>
        <vcmax>0.3</vcmax>
        <rd>0.4</rd>
      </exp_cox>
      <gstar_bf_a>0.012</gstar_bf_a>
      <gstar_bf_b>1.68</gstar_bf_b>
      <gstar_bf_c>42.7</gstar_bf_c>
      <R>8.31446</R>
    </leaf>
  </pars>
  <env>
    <leaf>
      <ca_conc>400</ca_conc>
      <o2_conc>0.21</o2_conc>
      <par>1000</par>
      <water_l>0</water_l>
      <sphag_l>0</sphag_l>
      <temp>25</temp>
      <vpd>0</vpd>
      <rh>0.8</rh>
      <atm_press>101325</atm_press>
      <wind>1</wind>
    </leaf>
  </env>
</default>

下面是我的退出代码（你会注意到我正在动态读取变量和值，请记住这一点）：

library(shiny)
library(xml2)
library(shinyWidgets)
library(magrittr)

# Read the XML file and extract the options
xml_file <- "your_path_for_where_you_saved_the_xml_file/leaf_default.xml"
xml_data <- read_xml(xml_file)

# Find the "pars" parent node
pars_leaf_node <- xml_data %>% xml_find_first(".//pars/leaf")

# Find the grandchild node names under "pars"
pars_grandchild_node_names <- xml_children(pars_leaf_node) %>% xml_name()
pars_grandchild_node_values <- xml_children(pars_leaf_node) %>% xml_text()

pars_tc <- xml_data %>% xml_find_first(".//pars/leaf/tlow_cox")
pars_tc_names <- xml_children(pars_tc) %>% xml_name()
pars_tc_values <- xml_children(pars_tc) %>% xml_text()

# Define the UI
ui <- fluidPage(
  titlePanel(""),
  sidebarLayout(
    sidebarPanel(
      prettyRadioButtons(
        "parts",
        "Please Select",
        choices = "pars",
        inline = TRUE,
        status = "danger",
        fill = TRUE 
      ),
      width = '10%',
      hr(),
      uiOutput("ui")
    ),
    mainPanel(
      # Add the main panel content here
    )
  )
)

# Define the server
server <- function(input, output, session) {
  
  # Update the UI based on the selected parent node
  observeEvent(input$parts, {
    grandchild_nodes <- pars_grandchild_node_names
    output$ui <- renderUI({
      fluidRow(
        lapply(grandchild_nodes, function(node_name) {
          if (node_name %in% pars_grandchild_node_names) {
            # Replace the condition with the grandchild nodes you want as text inputs or dropdowns
            node_index <- match(node_name, pars_grandchild_node_names)
            default_value <- pars_grandchild_node_values[node_index]
            
            if (node_name == "deltaA_prop") {
              column(6, 
                     sliderInput(node_name, label = node_name, value = default_value, min = 0.0, max = 1.0)
              )
            } else if (node_name == "solver_max") {
              column (6, 
                      numericInput(node_name, label = node_name, value = default_value, min = 0.0, max = 100.0, step = 0.01)
              )
            } else {
              column(6,
                     textInput(node_name, label = node_name, value = default_value)
              )
            }
            
            
          } 
          # else {
          #   # For other grandchild nodes, display as labels
          #   column(6,
          #          tags$label(node_name)
          #   )
          # }
        }) 
      )
    })
  })
  
  # Update the input values when the user makes changes
  observeEvent(input$ui, {
    for (node_name in grandchild_nodes) {
      if (node_name %in% pars_grandchild_node_names) {
        updateTextInput(session, node_name, value = input[[node_name]])
      }
    }
  })
}

shinyApp(ui = ui, server = server)