実験の解析で列同士の計算ができません。

前提・実現したいこと

deg V 　　　　 P
1 60.759441 3832.248535
2 60.967728 4010.33252
3 61.314758 4182.333496
4 61.800346 4363.109375
5 62.424274 4531.259277
6 63.186207 4676.081543
7 64.08577 4821.680664
8 65.122513 4959.410156
9 66.295921 5063.535645
10 67.605408 5148.52002
11 69.050308 5220.172852
12 70.629906 5270.594727
13 72.343414 5312.200195
14 74.18998 5327.998047
15 76.168671 5307.722656
16 78.278503 5276.194336
17 80.51844 5230.293945
18 82.887344 5169.510742
19 85.384056 5091.328613
20 88.007309 4983.586914
21 90.755821 4867.554199
22 93.62822 4741.881836
23 96.623062 4617.657227
24 99.738899 4478.993164
25 102.974159 4337.414063
26 106.327255 4188.319336
27 109.796532 4049.194824
28 113.380264 3914.283691
29 117.076698 3779.987793
30 120.88401 3642.640381
31 124.800339 3507.072266
32 128.823761 3379.536621
33 132.952286 3257.572266
34 137.183914 3142.929199
35 141.516586 3025.452148
36 145.948196 2912.166016
37 150.476563 2803.955078
38 155.099533 2704.56543
39 159.814835 2608.627441
40 164.620209 2515.900391
41 169.513351 2424.684082
42 174.491898 2336.593994
43 179.553497 2257.741211
44 184.695694 2180.728271
45 189.916077 2108.364746
46 195.212173 2036.926636
47 200.581451 1965.787354
48 206.021408 1900.326416
49 211.52951 1839.873291
50 217.103165 1781.361572
51 222.739777 1723.698364
52 228.436783 1668.30249
53 234.191498 1613.12439
54 240.001328 1563.54126
55 245.863632 1517.716553
56 251.775726 1471.445923
57 257.734924 1428.45459
58 263.738617 1385.710449
59 269.784058 1343.7052
60 275.868652 1307.821533
61 281.989624 1271.4823
62 288.144409 1236.746826
63 294.330231 1202.545654
64 300.544495 1169.286255
65 306.784485 1137.674072
66 313.047638 1109.344971
67 319.331238 1081.71582
68 325.63269 1054.230957
69 331.949432 1027.786133
70 338.278809 1001.711487
71 344.618286 976.874268
72 350.965302 955.03772
73 357.317322 932.877991
74 363.671906 911.542236
75 370.02655 890.964355
76 376.378754 870.263428
77 382.726196 851.384277
78 389.066406 833.918579
79 395.397064 815.621765
80 401.715851 798.555664
81 408.020508 781.843262
82 414.308777 765.042725
83 420.5784 750.68103
84 426.827301 737.580322
85 433.053253 723.40155
86 439.254242 710.717407
87 445.428192 698.111389
88 451.573059 684.774048
89 457.686951 673.187317
90 463.767944 662.488403
91 469.814117 650.804626
92 475.823669 640.664551
93 481.794861 629.753601
94 487.725922 618.717896
95 493.615173 609.311707
96 499.460968 599.706055
97 505.261749 590.139282
98 511.015991 582.231689
99 516.722168 573.07605
100 522.378784 564.246582
101 527.984497 557.269775
102 533.538025 549.514465
103 539.037903 542.22583
104 544.483032 535.457153
105 549.872192 527.604065
106 555.204041 520.76001
107 560.477661 514.639221
108 565.691956 507.537598
109 570.845825 501.534637
110 575.938354 496.261292
111 580.968567 491.370148
112 585.935608 485.490112
113 590.838623 480.082825
114 595.676758 474.445099
115 600.44928 469.841705
116 605.155457 464.916992
117 609.794617 459.040527
118 614.36615 455.168488
119 618.869385 449.771667
120 623.303711 444.344727
121 627.66864 440.63208
122 631.963684 435.725647
123 636.188293 431.232483
124 640.342102 428.213013
125 644.424683 424.217468
126 648.43573 420.388458
127 652.374756 417.008179
128 656.241516 412.82312
129 660.035706 409.277466
130 663.757019 406.27536
131 667.405273 401.965942
132 670.980225 397.924988
133 674.481689 394.522522
134 677.909485 389.804932
135 681.263367 386.430115
136 684.543335 383.919373
137 687.749329 379.290253
138 690.880981 376.243835
139 693.938477 373.831055
140 696.92157 369.78775
141 699.830322 367.390045
142 702.664612 364.730164
143 705.424438 361.085724
144 708.109863 358.366028
145 710.720825 354.070496
146 713.257263 349.107483
147 715.71936 345.245178
148 718.106995 340.484222
149 720.420227 336.11792
150 722.65918 333.065002
151 724.82373 328.437622
152 726.914063 323.554321
153 728.930298 319.840729
154 730.872314 315.114868
155 732.740356 310.529541
156 734.534241 307.20575
157 736.254333 302.430359
158 737.900513 297.697876
159 739.4729 293.305511
160 740.971558 287.381531
161 742.396545 282.267456
162 743.748047 277.934326
163 745.026001 273.217773
164 746.230469 269.20343
165 747.361572 264.872742
166 748.419434 260.025513
167 749.403992 256.654816
168 750.315369 252.918579
169 751.153625 248.363663
170 751.918823 244.624649
171 752.610901 239.954071
172 753.230103 235.131775
173 753.776367 231.345932
174 754.249695 226.89444
175 754.650085 222.198761
176 754.977722 217.808197
177 755.232483 212.764587
178 755.41449 208.041321
179 755.523621 203.770767
180 755.560059 199.221222
181 755.523621 195.74054
182 755.41449 192.993835
183 755.232483 189.208038
184 754.977722 186.174515
185 754.650085 183.059906
186 754.249695 178.986267
187 753.776367 176.082245
188 753.230103 173.402557
189 752.610901 169.753555
190 751.918823 166.756104
191 751.153625 163.085083
192 750.315369 158.718933
193 749.403992 155.715454
194 748.419434 152.163162
195 747.361572 148.474274
196 746.230469 146.443726
197 745.026001 143.454651
198 743.748047 140.446747
199 742.396545 138.774963
200 740.971558 135.610107
201 739.4729 132.653137
202 737.900513 131.040527
203 736.254333 128.299103
204 734.534241 126.106735
205 732.740356 124.474052
206 730.872314 121.680283
207 728.930298 119.378815
208 726.914063 117.924477
209 724.82373 115.088829
210 722.65918 113.922585
211 720.420227 112.416321
212 718.106995 110.205162
213 715.71936 109.28624
214 713.257263 107.92215
215 710.720825 106.33371
216 708.109863 105.658249
217 705.424438 104.448021
218 702.664612 102.898659
219 699.830322 101.958549
220 696.92157 100.461082
221 693.938477 98.903572
222 690.880981 98.084053
223 687.749329 96.690727
224 684.543335 95.577408
225 681.263367 95.128403
226 677.909485 93.782646
227 674.481689 93.025482
228 670.980225 92.898621
229 667.405273 92.045555
230 663.757019 92.014252
231 660.035706 92.145454
232 656.241516 91.49968
233 652.374756 91.254181
234 648.43573 91.073227
235 644.424683 89.93692
236 640.342102 89.706718
237 636.188293 89.32769
238 631.963684 88.350861
239 627.66864 88.377541
240 623.303711 87.687836
241 618.869385 86.764252
242 614.36615 86.695847
243 609.794617 86.440521
244 605.155457 85.877182
245 600.44928 86.633934
246 595.676758 86.475754
247 590.838623 86.392944
248 585.935608 87.149437
249 580.968567 87.191803
250 575.938354 86.854012
251 570.845825 87.525833
252 565.691956 87.209595
253 560.477661 87.149734
254 555.204041 87.606552
255 549.872192 87.146339
256 544.483032 87.267715
257 539.037903 87.625763
258 533.538025 87.133293
259 527.984497 86.935753
260 522.378784 87.130753
261 516.722168 86.699577
262 511.015991 87.141319
263 505.261749 87.297157
264 499.460968 86.876099
265 493.615173 87.087479
266 487.725922 86.604828
267 481.794861 85.820374
268 475.823669 85.599136
269 469.814117 85.022171
270 463.767944 84.107925
271 457.686951 83.941589
272 451.573059 83.261894
273 445.428192 82.433533
274 439.254242 82.109291
275 433.053253 81.208023
276 426.827301 80.543533
277 420.5784 80.361694
278 414.308777 79.505531
279 408.020508 79.165115
280 401.715851 79.043236
281 395.397064 78.375763
282 389.066406 77.994049
283 382.726196 77.193893
284 376.378754 76.364792
285 370.02655 77.854179
286 363.671906 77.807281
287 357.317322 77.578583
288 350.965302 78.204414
289 344.618286 79.848328
290 338.278809 81.091278
291 331.949432 82.53672
292 325.63269 83.931908
293 319.331238 84.466751
294 313.047638 85.744179
295 306.784485 88.259964
296 300.544495 89.432213
297 294.330231 90.543999
298 288.144409 92.377968
299 281.989624 93.964478
300 275.868652 94.888809
301 269.784058 96.509659
302 263.738617 95.80748
303 257.734924 97.631409
304 251.775726 99.167824
305 245.863632 100.050606
306 240.001328 101.415634
307 234.191498 101.018906
308 228.436783 101.418983
309 222.739777 101.924667
310 217.103165 102.226089
311 211.52951 102.430382
312 206.021408 102.410034
313 200.581451 103.015747
314 195.212173 103.39888
315 189.916077 103.117844
316 184.695694 102.748009
317 179.553497 102.841446
318 174.491898 103.096382
319 169.513351 103.098442
320 164.620209 102.99942
321 159.814835 101.990891
322 155.099533 102.601952
323 150.476563 103.526268
324 145.948196 102.162163
325 141.516586 101.286209
326 137.183914 101.3405
327 132.952286 101.598938
328 128.823761 101.229904
329 124.800339 100.387604
330 120.88401 100.486526
331 117.076698 100.635056
332 113.380264 99.933586
333 109.796532 99.498901
334 106.327255 99.096779
335 102.974159 98.997421
336 99.738899 99.326202
337 96.623062 99.280312
338 93.62822 98.615112
339 90.755821 97.691856
340 88.007309 96.515427
341 85.384056 96.018196
342 82.887344 95.037224
343 80.51844 93.634132
344 78.278503 93.11763
345 76.168671 93.420097
346 74.18998 92.624725
347 72.343414 90.398849
348 70.629906 88.653633
349 69.050308 88.024277
350 67.605408 87.390419
351 66.295921 86.606239
352 65.122513 84.881752
353 64.08577 82.625198
354 63.186207 81.14933
355 62.424274 79.465187
356 61.800346 77.388855
357 61.314758 74.88063
358 60.967728 72.684853
359 60.759441 70.309669

のcsvファイルを
dP(i) = 1 / (12 * 1) * (P(i - 2) - 8 * P(i - 1) + 8 * P(i + 1) - P(i + 2))
dV(i) = 1 / (12 * 1) * (V(i - 2) - 8 * V(i - 1) + 8 * V(i + 1) - V(i + 2))
（iは行数）
というような計算を行いたい,Vの列の隣に計算結果を追加したいのですがどのようなコードを書くと実行できるでしょうか。
pandasを使用したものですとうれしいです。
実験の解析で躓いています。どうかよろしくお願いします。

行動規範の内容に同意します

回答1件

ベストアンサー

Series.shift で列を指定した行数分ずらすことができるので、これを使って計算すればよいと思います。
最初の2行、最後の2行は i - 1, i - 2, i + 1, i + 2 が定義できないので NaN になります。

pandas.Series.shift — pandas 1.0.3 documentation

python
1df["dP"] = 1 / (12 * 1) * (df.P.shift(-2) - 8 * df.P.shift(-1) + 8 * df.P.shift(2) - df.P.shift(2))
2df["dV"] = 1 / (12 * 1) * (df.V.shift(-2) - 8 * df.V.shift(-1) + 8 * df.V.shift(2) - df.V.shift(2))
3df