如何防止gnuplot拉伸情节

Question

我有代表地理边界的可变数据。我们生成一个包含边界图像的报告。此图像固定为700x500。我喜欢在没有拉伸的情况下绘制边界。居中会很棒，但不是必需的。

以下是一个示例数据集：

-87.6947 39.6481
-87.6949 39.6395
-87.7024 39.6375
-87.7137 39.6403
-87.7140 39.6345
-87.7128 39.6284
-87.7059 39.6263
-87.7047 39.6228
-87.7104 39.6222
-87.7114 39.6159
-87.7157 39.6115
-87.7200 39.6056
-87.7191 39.6013
-87.7121 39.6020
-87.7043 39.6009
-87.7037 39.5925
-87.6900 39.5920
-87.6863 39.6004
-87.6772 39.6028
-87.6700 39.6060
-87.6688 39.6152
-87.6696 39.6205
-87.6738 39.6212
-87.6756 39.6278
-87.6737 39.6340
-87.6779 39.6396
-87.6836 39.6441
-87.6868 39.6490
-87.6947 39.6481
-87.6947 39.6481

-87.7101 40.0760
-87.7173 40.0671
-87.7100 40.0588
-87.6959 40.0606
-87.6886 40.0645
-87.6700 40.0638
-87.6471 40.0639
-87.6470 40.0494
-87.6528 40.0434
-87.6452 40.0354
-87.6394 40.0199
-87.6396 39.9918
-87.6437 39.9884
-87.6458 39.9753
-87.6366 39.9653
-87.6230 39.9724
-87.6183 39.9787
-87.6240 39.9891
-87.6348 39.9932
-87.6359 40.0209
-87.6274 40.0296
-87.6294 40.0403
-87.6294 40.0503
-87.6279 40.0646
-87.6258 40.0764
-87.6221 40.0795
-87.6227 40.0806
-87.6341 40.0810
-87.6327 40.0858
-87.6301 40.0920
-87.6269 40.1009
-87.6259 40.1057
-87.6314 40.1052
-87.6372 40.1049
-87.6437 40.1050
-87.6517 40.1047
-87.6561 40.1047
-87.6577 40.1014
-87.6562 40.0960
-87.6519 40.0932
-87.6493 40.0890
-87.6445 40.0858
-87.6377 40.0848
-87.6375 40.0804
-87.6462 40.0809
-87.6456 40.0768
-87.6427 40.0718
-87.6367 40.0708
-87.6381 40.0660
-87.6930 40.0657
-87.6958 40.0694
-87.6985 40.0728
-87.7033 40.0750
-87.7101 40.0760
-87.7101 40.0760

以下是gnuplot命令：

unset logscale xy
set term png font arial 8 size 700,500
set output 'map.png'
plot 'boundary.dat' with lines

这是我得到的：

这是我想要的（仅限于700x500画布上）：