title: python openpyxl read excel too slow
body: <p>I have a .xlsx file, owning 1841 rows. Each row has 30 columns.Use openpyxl saving the whole info to a list. </p>
  
  <pre><code>def get_value(i,ws,article_row):
      value=ws.cell(row=article_row,column=i).value
      i+=1
      return value,i
  def geneList(f):
      wb = load_workbook(filename=f, read_only=True)
      ws = wb.worksheets[0]
      max_row = ws.max_row
      info_list=[]
      for ar_row in range(2,max_row+1):
          i=3#start from the 3rd column: sourceid 
          sourceID,i=get_value(i,ws,ar_row)
          pv,i=get_value(i,ws,ar_row)
          pubtype,i=get_value(i,ws,ar_row)
  ......
          item_dict={'sourceID':sourceID,'pv':pv,'pubtype':pubtype,
                     ...}
      info_list.append(item_dict)
  </code></pre>
  
  <p>But it takes around 20 mins to read all the information. I do not know how to solve this problem? It is to slow to parse the information. Convert .xlsx to .csv? Or use another tool to read?</p>