title: How to put axes behind the graph?
body: <p>I created a graph using geom_line and geom_point via ggplot. I want my axes to meet at (0,0) and I want my lines and data points to be in front of the axes instead of behind as shown:</p>
  
  <p><img src="https://i.stack.imgur.com/JIeRs.png" alt="graph"></p>
  
  <p>I've tried:</p>
  
  <ol>
  <li>coord_cartesian(clip = 'off')</li>
  <li>putting geom_line and geom_point at the end</li>
  <li>creating a base graph then add geom_line and geom_point</li>
  <li>playing around with the functions of coord_cartesian</li>
  <li>manually setting xlim =c(-0.1, 25) and ylim=c(-0.1, 1500)</li>
  </ol>
  
  <p>data7 is as follows:</p>
  
  <pre><code>   Treatment Days N        mean         sd          se
  1          1    0 7 204.7000000  41.579963  15.7157488
  2          1    2 7 255.0571429  41.116617  15.5406205
  3          1    5 7 290.6000000  49.506498  18.7116974
  4          1    8 7 330.8142857  49.044144  18.5369442
  5          1   12 7 407.5142857  95.584194  36.1274294
  6          1   15 7 540.8571429 164.299390  62.0993323
  7          1   19 7 737.5285714 308.786359 116.7102736
  8          1   21 7 978.4571429 502.506726 189.9296898
  9          2    0 7 205.7428571  46.902482  17.7274721
  10         2    2 7 227.5571429  47.099889  17.8020846
  11         2    5 7 232.4857143  59.642922  22.5429054
  12         2    8 7 247.9857143  66.478529  25.1265220
  13         2   12 7 272.0428571  79.173162  29.9246423
  14         2   15 7 289.1142857  82.847016  31.3132288
  15         2   19 7 312.3857143 105.648591  39.9314140
  16         2   21 7 334.7142857 121.569341  45.9488920
  17         3    0 7 212.2285714  47.549263  17.9719320
  18         3    2 7 235.4142857  52.689671  19.9148237
  19         3    5 7 177.0714286  54.895225  20.7484447
  20         3    8 7 205.2571429  72.611451  27.4445489
  21         3   12 7 247.8142857 119.369558  45.1174522
  22         3   15 7 280.4285714 140.825847  53.2271669
  23         3   19 7 366.9142857 210.573799  79.5894149
  24         3   21 7 451.0428571 289.240793 109.3227438
  25         4    0 7 211.6857143  24.329161   9.1955587
  26         4    2 7 227.8428571  28.762525  10.8712127
  27         4    5 7 205.9428571  49.148919  18.5765451
  28         4    8 7 153.1142857  25.189246   9.5206399
  29         4   12 7 128.2571429  43.145910  16.3076210
  30         4   15 7 104.1714286  45.161662  17.0695038
  31         4   19 7  85.4714286  51.169708  19.3403318
  32         4   21 7  66.9000000  52.724567  19.9280133
  33         5    0 7 216.7857143  39.957829  15.1026398
  34         5    2 7 212.2000000  27.037135  10.2190765
  35         5    5 7 115.5000000  37.094070  14.0202405
  36         5    8 7  46.1000000  34.925492  13.2005952
  37         5   12 7  29.3142857  24.761222   9.3588621
  38         5   15 6  10.0666667  13.441974   5.4876629
  39         5   19 6   6.4000000  11.692733   4.7735382
  40         5   21 6   5.3666667  12.662017   5.1692467
  41         6    0 7 206.6857143  40.359155  15.2543269
  42         6    2 7 197.0428571  40.608327  15.3485048
  43         6    5 7 106.2142857  58.279654  22.0276388
  44         6    8 7  46.0571429  62.373014  23.5747833
  45         6   12 7  31.7571429  49.977457  18.8897031
  46         6   15 7  28.1142857  45.437995  17.1739480
  47         6   19 7  26.2857143  38.414946  14.5194849
  48         6   21 7  32.7428571  53.203003  20.1088450
  49         7    0 7 193.2000000  37.300447  14.0982437
  50         7    2 7 133.2428571  26.462606  10.0019250
  51         7    5 7   3.8142857   7.445900   2.8142857
  52         7    8 7   0.7142857   1.496026   0.5654449
  53         7   12 7   0.0000000   0.000000   0.0000000
  54         7   15 7   0.0000000   0.000000   0.0000000
  55         7   19 7   0.0000000   0.000000   0.0000000
  56         7   21 7   0.0000000   0.000000   0.0000000
  </code></pre>
  
  <p>My code is as follows:</p>
  
  <pre><code>ggplot(data7, aes(Days, mean, color=Treatment)) +
    geom_line() +
    geom_errorbar(aes(ymin=mean-se, ymax=mean+se), width=0.5, size= 0.25) +
    geom_point(size=2.5) +
    scale_colour_hue(limits = c("1", "2", "3", "4", "5", "6", "7")) +
    scale_x_continuous(expand = c(0, 0), limits = c(0, NA), breaks = scales::pretty_breaks(n = 10)) +
    scale_y_continuous(expand = c(0, 0), limits = c(0, NA), breaks = scales::pretty_breaks(n = 8)) +
    theme_classic() +
    theme(axis.text = element_text(color = "#000000"), plot.title = element_text(hjust = 0.5)) +
    coord_cartesian(clip = 'off')
  </code></pre>