title: Data cleaning & subsetting in nested list
body: <p>I couldn't find any previous questions which addresses these steps in a nested list. My own attems hasn't got me anywhere either!</p>
  <p>I have a nested list <code>df</code>.</p>
  <ol>
  <li>I would like to change the column names of the 3 first columns in
  all data.frames to <code>c(&quot;one&quot;,&quot;two&quot;,&quot;three&quot;)</code>.</li>
  <li>In each data frame want to keep the 3 first columns and the columns
  with the same name as the data frame name in the list.</li>
  <li>Now each data frame has 4 columns. In each data frame I want to keep the values in the second columns if the values of the fourth column is bigger than 3.</li>
  <li>Return a nested list, with the name of each data frame and selected
  values from the second column (in step 4).</li>
  </ol>
  <p><code>Purrr</code> and <code>dplyr</code> approach are preferred but everything else is much appreciated!</p>
  <pre><code>&gt; dput(map_depth(df,1, head))
  list(`CD8_C01-LEF1` = structure(list(...1 = c(&quot;1236&quot;, &quot;6194&quot;, 
  &quot;51176&quot;, &quot;6402&quot;, &quot;6137&quot;, &quot;1937&quot;), ...2 = c(&quot;CCR7&quot;, &quot;RPS6&quot;, &quot;LEF1&quot;, 
  &quot;SELL&quot;, &quot;RPL13&quot;, &quot;EEF1G&quot;), ...3 = c(448.275813024615, 114.565282822255, 
  405.993571415472, 352.462886197845, 152.430598462657, 73.5226212775651
  ), `P-value*` = c(0, 2.35914832807463e-150, 0, 0, 1.03146807397557e-195, 
  3.00681346250943e-98), `CD8_C01-LEF1` = c(6.3388353508401, 1.36075129906401, 
  5.11667843995657, 5.22902495053118, 1.35703181746742, 1.72815687302818
  ), `CD8_C02-GPR183` = c(2.71993044636725, 0.755445092850178, 
  2.26029822474036, 3.57732840656951, 0.757664532314421, 0.732003573596204
  ), `CD8_C03-CX3CR1` = c(-2.50016459757821, 0.0430813598361915, 
  -1.47763877045973, -1.31104077043168, -0.118054173396857, -0.217984797372657
  ), `CD8_C04-GZMK` = c(-0.639352384551204, -0.304854019068466, 
  -1.400271288872, -1.56965980479594, -0.128422617265835, -0.701864111617954
  ), `CD8_C05-CD6` = c(-2.35873754058284, -0.115888861319928, -2.08628173736428, 
  -3.32630706764402, -0.177640817498698, -0.215754243123614), `CD8_C06-CD160` = c(-2.85558322130952, 
  -0.29530343951866, -2.20232116143474, -3.274807762691, -0.440783845861116, 
  -0.56207661416919), `CD8_C07-LAYN` = c(-2.75671138163062, -0.887003245107014, 
  -2.40845402752497, -3.47698326675668, -1.03656381624963, -1.46468960616135
  ), `CD8_C08-SLC4A10` = c(-2.68199272253543, 0.0292368512820967, 
  -2.1581654239029, -2.99895134853712, 0.0615744908900675, 0.192173783941343
  )), row.names = c(NA, 6L), class = &quot;data.frame&quot;), `CD8_C02-GPR183` = structure(list(
      ...1 = c(&quot;3575&quot;, &quot;4050&quot;, &quot;1901&quot;, &quot;6653&quot;, &quot;1880&quot;, &quot;10628&quot;), 
      ...2 = c(&quot;IL7R&quot;, &quot;LTB&quot;, &quot;S1PR1&quot;, &quot;SORL1&quot;, &quot;GPR183&quot;, &quot;TXNIP&quot;
      ), ...3 = c(268.347035159053, 151.397715576146, 423.815475272167, 
      154.131971403975, 161.502687932662, 138.188069200824), `P-value*` = c(0, 
      1.63481853000449e-194, 0, 1.09616441981898e-197, 3.47999420200636e-206, 
      5.87606326954945e-179), `CD8_C01-LEF1` = c(2.25872137515665, 
      1.06433926285014, 2.06890434595653, 1.77222927526522, -2.32256398023726, 
      1.17445992511194), `CD8_C02-GPR183` = c(3.58534594694992, 
      2.33774626980998, 3.1044712936119, 3.00075778716827, 1.54874669286004, 
      2.11053414857411), `CD8_C03-CX3CR1` = c(-2.73122665345433, 
      -3.23251051546321, 2.76359001828421, 0.899851788567591, -3.4595583469893, 
      1.9924219816788), `CD8_C04-GZMK` = c(-1.20359289904198, -2.27859013855459, 
      -0.289843306560729, 0.0930099548084882, 0.293766916539111, 
      -1.05998934689132), `CD8_C05-CD6` = c(0.771026257612103, 
      -1.84446654315228, -1.92859019625536, -0.993527571866541, 
      -0.517242518264243, -1.05505195656161), `CD8_C06-CD160` = c(-1.26433565787961, 
      -3.62072638085859, -1.99838091859197, -2.66224984657089, 
      -3.84677781455005, -0.741084525734145), `CD8_C07-LAYN` = c(-4.85420539962432, 
      -3.79535857695107, -2.07599716553024, -2.41001692585172, 
      -3.66993376805675, -1.90910214659534), `CD8_C08-SLC4A10` = c(1.79563839118781, 
      0.431971358693421, 0.24665792844753, 0.820564247625701, -0.941462395796914, 
      0.224912511574641)), row.names = c(NA, 6L), class = &quot;data.frame&quot;), 
      `CD8_C03-CX3CR1` = structure(list(...1 = c(&quot;5341&quot;, &quot;1524&quot;, 
      &quot;83888&quot;, &quot;2214&quot;, &quot;343413&quot;, &quot;10219&quot;), ...2 = c(&quot;PLEK&quot;, &quot;CX3CR1&quot;, 
      &quot;FGFBP2&quot;, &quot;FCGR3A&quot;, &quot;FCRL6&quot;, &quot;KLRG1&quot;), ...3 = c(372.816216710618, 
      713.554708746553, 575.834099328186, 419.996034284325, 215.715234731706, 
      281.827177706662), `P-value*` = c(&quot;0&quot;, &quot;0&quot;, &quot;0&quot;, &quot;0&quot;, &quot;3.5450627744914998E-266&quot;, 
      &quot;0&quot;), `CD8_C01-LEF1` = c(-1.34745098111019, -0.39476162886016, 
      -0.248194028712413, -0.326944139043036, -0.833877751680806, 
      -0.822668603983214), `CD8_C02-GPR183` = c(0.50737446056126, 
      -0.495638146054913, -0.484905896571723, -0.125753818325312, 
      0.0263098770399738, 0.894340812937189), `CD8_C03-CX3CR1` = c(6.36825282208761, 
      5.38301238794739, 5.26196506464758, 5.6197563760267, 5.8532850807879, 
      5.36851683724817), `CD8_C04-GZMK` = c(1.44463895049283, -0.513803138075432, 
      -0.125340966094923, 0.2447981258131, 1.34537977512099, 2.10784813093189
      ), `CD8_C05-CD6` = c(-0.718776566594413, -0.795121492384525, 
      -0.681892196238474, -0.421395883952147, 0.0987360993173341, 
      -1.35585804120358), `CD8_C06-CD160` = c(-0.550964233191398, 
      -0.794078725052049, -0.707741972359531, -0.156207202527366, 
      2.24842830259497, -1.28977809817504), `CD8_C07-LAYN` = c(0.0641870785667258, 
      -0.785201010640904, -0.631939964779986, -0.340799120353511, 
      0.271892089522186, 0.236064375692484), `CD8_C08-SLC4A10` = c(1.40102283829925, 
      -0.158585496249154, -0.056110756095033, 0.00915832466806331, 
      -0.085141865592199, 3.78847417230501)), row.names = c(NA, 
      6L), class = &quot;data.frame&quot;))
  </code></pre>