I'm using gekko to solve a MINLP problem. I'm using the APOPT solver since is the only one that can provide integer solution, which are strictly needed in my case.
The issue I have is that every time I run the solver I have a different solution, even for very small cases, so I can't be sure about the optimality of the solutions. From some solutions to others there are important differences in the objective final value.
I've noticed that only 1 iteration takes place, and I don't know if it should be like this. Also, it runs for less than 1 second when it could run longer and find better solutions.
Below the output of one of this runs:
--------- APM Model Size ------------
Each time step contains
Objects : 86
Constants : 0
Variables : 606
Intermediates: 0
Connections : 806
Equations : 1046
Residuals : 1046
Number of state variables: 606
Number of total equations: - 172
Number of slack variables: - 40
---------------------------------------
Degrees of freedom : 394
----------------------------------------------
Steady State Optimization with APOPT Solver
----------------------------------------------
Iter: 1 I: 0 Tm: 0.38 NLPi: 28 Dpth: 0 Lvs: 0 Obj: 1.27E+09 Gap: 0.00E+00
Successful solution
---------------------------------------------------
Solver : APOPT (v1.0)
Solution time : 0.38800000000628643 sec
Objective : 1271480486.0000000
Successful solution
---------------------------------------------------
I would appreciate any advice on how to tweak the solver so I can have consistent solutions. Thanks in advance
EDIT
I'm adding the code (reduced version). Basically what I'm trying to do is finding the best location for n warehouse based on the demand of m cities, which are represented by the corresponding hexagon in the h3 library.
from gekko import GEKKO
from random import randint
import pandas as pd
if __name__ == '__main__':
n_warehouses = 6
df_aggreg = pd.DataFrame.from_dict({'hex_id_basic': {32: 0, 12: 1, 2: 2, 3: 3, 22: 4, 24: 5, 38: 6, 8: 7, 19: 8, 27: 9, 21: 10, 25: 11, 28: 12, 26: 13, 29: 14, 30: 15, 31: 16, 1: 17, 20: 18, 18: 19, 17: 20, 33: 21, 35: 22, 14: 23, 13: 24, 11: 25, 10: 26, 36: 27, 6: 28, 5: 29, 4: 30, 16: 31, 34: 32, 0: 33, 23: 34, 15: 35, 9: 36, 37: 37, 7: 38, 39: 39}, 'value': {32: 1808, 12: 847, 2: 847, 3: 847, 22: 847, 24: 847, 38: 847, 8: 847, 19: 847, 27: 847, 21: 452, 25: 452, 28: 452, 26: 452, 29: 452, 30: 452, 31: 452, 1: 452, 20: 452, 18: 452, 17: 452, 33: 452, 35: 452, 14: 452, 13: 452, 11: 452, 10: 452, 36: 452, 6: 452, 5: 452, 4: 452, 16: 452, 34: 169, 0: 169, 23: 84, 15: 84, 9: 84, 37: 84, 7: 84, 39: 84}})
distance_matrix = [[0, 278320, 302712, 117682, 283287, 225645, 303065, 258900, 252165, 453768, 389125, 305694, 377415, 445329, 176671, 16098, 95378, 272352, 153948, 247011, 153063, 175620, 184734, 253592, 235204, 275271, 204377, 140151, 270207, 254950, 364642, 92383, 239928, 300635, 394936, 291140, 293377, 205417, 253778, 313127], [278320, 0, 144398, 187013, 244571, 107924, 257813, 279533, 334530, 195669, 205157, 84028, 109937, 187707, 427560, 265135, 188779, 292672, 307462, 280094, 408319, 281660, 131476, 440829, 46693, 204251, 233509, 147273, 263519, 267077, 185835, 310005, 254863, 323378, 119817, 407585, 280337, 171576, 280105, 261055], [302712, 144398, 0, 185183, 377007, 234161, 392715, 170354, 237346, 307577, 347861, 228110, 138929, 301200, 476655, 286696, 244493, 179154, 254571, 176769, 387398, 378208, 238178, 372115, 163476, 79788, 152001, 222356, 146928, 158337, 62584, 289416, 375428, 203381, 217686, 310387, 155900, 289533, 173468, 397435], [117682, 187013, 185183, 0, 291864, 179791, 311714, 170740, 192926, 379238, 347869, 240050, 272172, 370968, 293195, 101616, 87586, 185977, 129253, 162328, 222594, 233040, 150108, 262697, 153805, 162481, 109099, 101869, 173375, 162759, 246974, 123207, 265470, 218641, 306739, 255114, 197339, 195959, 167223, 320151], [283287, 244571, 377007, 291864, 0, 142846, 20212, 455483, 484791, 287216, 161617, 183085, 340463, 280631, 326676, 282534, 212575, 470828, 409823, 449527, 434084, 135211, 148574, 531347, 213849, 411617, 394742, 190552, 450777, 445332, 427673, 367985, 53066, 504293, 288485, 544788, 473256, 96874, 453151, 29897], [225645, 107924, 234161, 179791, 142846, 0, 158910, 325969, 365598, 232092, 169623, 84652, 214438, 223750, 344437, 216987, 130954, 340949, 308549, 322092, 374352, 178834, 41429, 440518, 71333, 272261, 268233, 88085, 317511, 314784, 285789, 286639, 147154, 374185, 190689, 432588, 338741, 64095, 324564, 164244], [303065, 257813, 392715, 311714, 20212, 158910, 0, 474649, 504627, 286841, 156847, 192075, 350549, 280649, 341260, 302511, 232768, 489976, 430017, 468858, 453490, 151205, 167295, 551499, 229266, 429328, 414077, 210234, 469552, 464393, 442147, 388101, 68990, 523448, 294341, 564878, 491892, 116277, 472394, 10359], [258900, 279533, 170354, 170740, 455483, 325969, 474649, 0, 68930, 467349, 478557, 358082, 308273, 460170, 428178, 244879, 258325, 15394, 131661, 13671, 271974, 403214, 307634, 213649, 272011, 90917, 61801, 266220, 26455, 12593, 202481, 195575, 434164, 48812, 379747, 140257, 39308, 358628, 6107, 482200], [252165, 334530, 237346, 192926, 484791, 365598, 504627, 68930, 0, 526826, 526392, 408559, 373685, 519349, 407413, 240840, 276462, 66186, 101574, 60620, 226811, 414422, 341075, 147167, 320118, 158889, 101274, 294543, 95127, 79800, 271409, 171262, 456912, 68984, 441013, 74111, 100302, 388712, 64684, 513007], [453768, 195669, 307577, 379238, 287216, 232092, 286841, 467349, 526826, 0, 136244, 148461, 178102, 8441, 573471, 443171, 358499, 479086, 502816, 469837, 595669, 392502, 273266, 636429, 225844, 383011, 426871, 313638, 447989, 454756, 317090, 500323, 328239, 507228, 90088, 600610, 461075, 278672, 468809, 282694], [389125, 205157, 347861, 347869, 161617, 169623, 156847, 478557, 526392, 136244, 0, 121715, 255074, 131581, 475633, 382466, 297470, 492617, 477097, 477118, 540843, 284992, 206940, 609805, 206849, 408806, 425937, 256909, 465228, 466469, 379467, 455895, 209773, 524589, 174173, 596319, 483539, 187375, 478271, 151054], [305694, 84028, 228110, 240050, 183085, 84652, 192075, 358082, 408559, 148461, 121715, 0, 158796, 140049, 428839, 295540, 210329, 371886, 368057, 357279, 450043, 256851, 125251, 502181, 89028, 287097, 307444, 165570, 343975, 345858, 265337, 357240, 207855, 403529, 110982, 479964, 361969, 139306, 358064, 193009], [377415, 109937, 138929, 272172, 340463, 214438, 350549, 308273, 373685, 178102, 255074, 158796, 0, 173125, 534732, 362967, 293628, 317765, 374520, 313604, 493385, 391108, 241276, 501197, 156178, 218494, 280742, 254733, 285601, 295994, 139047, 393079, 358593, 342270, 90310, 447455, 294687, 278510, 310960, 351759], [445329, 187707, 301200, 370968, 280631, 223750, 280649, 460170, 519349, 8441, 131581, 140049, 173125, 0, 565355, 434730, 350062, 472002, 494725, 462533, 587263, 384786, 264901, 628392, 217517, 376220, 419266, 305200, 440993, 447576, 311937, 491975, 321105, 500318, 84177, 593082, 454296, 270683, 461573, 276700], [176671, 427560, 476655, 293195, 326676, 344437, 341260, 428178, 407413, 573471, 475633, 428839, 534732, 565355, 0, 192659, 241685, 440309, 306114, 415366, 213722, 192267, 305547, 353506, 381057, 451860, 378110, 280381, 442537, 425977, 539074, 236503, 273614, 465255, 533298, 426186, 464854, 295413, 422602, 351173], [16098, 265135, 286696, 101616, 282534, 216987, 302511, 244879, 240840, 443171, 382466, 295540, 362967, 434730, 192659, 0, 86037, 258560, 144482, 233219, 158401, 180937, 176621, 250690, 222751, 259395, 189468, 130132, 255508, 240568, 348587, 87437, 241145, 287389, 382525, 282778, 278823, 201018, 239867, 312431], [95378, 188779, 244493, 87586, 212575, 130954, 232768, 258325, 276462, 358499, 297470, 210329, 293628, 350062, 241685, 86037, 0, 273554, 197249, 249773, 243741, 146171, 90840, 321549, 143532, 241689, 196668, 44890, 260330, 250266, 306721, 160762, 180583, 306135, 302150, 332965, 284225, 121772, 254773, 241969], [272352, 292672, 179154, 185977, 470828, 340949, 489976, 15394, 66186, 479086, 492617, 371886, 317765, 472002, 440309, 258560, 273554, 0, 140627, 25344, 279225, 418280, 322922, 213131, 286282, 99366, 77144, 281612, 32238, 26277, 207287, 206362, 449552, 33473, 391005, 133626, 34477, 373979, 19000, 497504], [153948, 307462, 254571, 129253, 409823, 308549, 430017, 131661, 101574, 502816, 477097, 368057, 374520, 494725, 306114, 144482, 197249, 140627, 0, 117996, 141824, 323726, 276426, 134201, 280163, 191685, 105340, 226127, 152834, 133897, 305377, 69716, 375475, 161033, 424673, 138867, 170911, 317471, 125583, 439203], [247011, 280094, 176769, 162328, 449527, 322092, 468858, 13671, 60620, 469837, 477118, 357279, 313604, 462533, 415366, 233219, 249773, 25344, 117996, 0, 258348, 393955, 302253, 202640, 270296, 98356, 54784, 259602, 38118, 20016, 211973, 182205, 426898, 56395, 382945, 133870, 52974, 352657, 7588, 476592], [153063, 408319, 387398, 222594, 434084, 374352, 453490, 271974, 226811, 595669, 540843, 450043, 493385, 587263, 213722, 158401, 243741, 279225, 141824, 258348, 0, 314904, 334581, 140210, 370743, 331489, 244983, 286515, 294300, 275249, 442428, 100328, 387881, 294243, 528076, 223497, 311245, 358451, 265867, 463708], [175620, 281660, 378208, 233040, 135211, 178834, 151205, 403214, 414422, 392502, 284992, 256851, 391108, 384786, 192267, 180937, 146171, 418280, 323726, 393955, 314904, 0, 150414, 428871, 237099, 386147, 341933, 156045, 406310, 395685, 438153, 267684, 82364, 450314, 367218, 462586, 430241, 117601, 399353, 161423], [184734, 131476, 238178, 150108, 148574, 41429, 167295, 307634, 341075, 273266, 206940, 125251, 241276, 264901, 305547, 176621, 90840, 322922, 276426, 302253, 334581, 150414, 0, 406344, 86738, 264273, 247556, 50786, 302265, 297224, 294689, 249321, 137664, 356394, 227861, 405170, 324686, 53055, 305544, 174613], [253592, 440829, 372115, 262697, 531347, 440518, 551499, 213649, 147167, 636429, 609805, 502181, 501197, 628392, 353506, 250690, 321549, 213131, 134201, 202640, 140210, 428871, 406344, 0, 414364, 298374, 221122, 355576, 240067, 222654, 413797, 163640, 491733, 212409, 556786, 103608, 247427, 443322, 208464, 561173], [235204, 46693, 163476, 153805, 213849, 71333, 229266, 272011, 320118, 225844, 206849, 89028, 156178, 217517, 381057, 222751, 143532, 286282, 280163, 270296, 370743, 237099, 86738, 414364, 0, 208101, 219280, 101025, 259858, 260053, 214484, 274518, 217001, 318654, 159780, 391112, 279361, 131548, 271564, 233971], [275271, 204251, 79788, 162481, 411617, 272261, 429328, 90917, 158889, 383011, 408806, 287097, 218494, 376220, 451860, 259395, 241689, 99366, 191685, 98356, 331489, 386147, 264273, 298374, 208101, 0, 86592, 233845, 67147, 79218, 115829, 239530, 400051, 124610, 293938, 231168, 78076, 317319, 94401, 435547], [204377, 233509, 152001, 109099, 394742, 268233, 414077, 61801, 101274, 426871, 425937, 307444, 280742, 419266, 378110, 189468, 196668, 77144, 105340, 54784, 244983, 341933, 247556, 221122, 219280, 86592, 0, 204896, 66374, 53769, 200202, 155140, 372506, 110258, 342408, 174094, 90128, 297872, 58728, 421827], [140151, 147273, 222356, 101869, 190552, 88085, 210234, 266220, 294543, 313638, 256909, 165570, 254733, 305200, 280381, 130132, 44890, 281612, 226127, 259602, 286515, 156045, 50786, 355576, 101025, 233845, 204896, 0, 263729, 256622, 282929, 198993, 168664, 314976, 258111, 356656, 286974, 94168, 263557, 218490], [270207, 263519, 146928, 173375, 450777, 317511, 469552, 26455, 95127, 447989, 465228, 343975, 285601, 440993, 442537, 255508, 260330, 32238, 152834, 38118, 294300, 406310, 302265, 240067, 259858, 67147, 66374, 263729, 0, 19120, 176392, 213505, 432376, 59886, 359568, 165204, 23979, 354255, 31668, 476705], [254950, 267077, 158337, 162759, 445332, 314784, 464393, 12593, 79800, 454756, 466469, 345858, 295994, 447576, 425977, 240568, 250266, 26277, 133897, 20016, 275249, 395685, 297224, 222654, 260053, 79218, 53769, 256622, 19120, 0, 192090, 195450, 424902, 59414, 367175, 152072, 38895, 348532, 15183, 471835], [364642, 185835, 62584, 246974, 427673, 285789, 442147, 202481, 271409, 317090, 379467, 265337, 139047, 311937, 539074, 348587, 306721, 207287, 305377, 211973, 442428, 438153, 294689, 413797, 214484, 115829, 200202, 282929, 176392, 192090, 0, 346396, 430496, 224040, 228276, 340846, 177161, 344487, 206946, 445989], [92383, 310005, 289416, 123207, 367985, 286639, 388101, 195575, 171262, 500323, 455895, 357240, 393079, 491975, 236503, 87437, 160762, 206362, 69716, 182205, 100328, 267684, 249321, 163640, 274518, 239530, 155140, 198993, 213505, 195450, 346396, 0, 328145, 229377, 429805, 200778, 233973, 281930, 189695, 397850], [239928, 254863, 375428, 265470, 53066, 147154, 68990, 434164, 456912, 328239, 209773, 207855, 358593, 321105, 273614, 241145, 180583, 449552, 375475, 426898, 387881, 82364, 137664, 491733, 217001, 400051, 372506, 168664, 432376, 424902, 430496, 328145, 0, 482764, 317893, 512855, 455638, 86038, 431229, 79283], [300635, 323378, 203381, 218641, 504293, 374185, 523448, 48812, 68984, 507228, 524589, 403529, 342270, 500318, 465255, 287389, 306135, 33473, 161033, 56395, 294243, 450314, 356394, 212409, 318654, 124610, 110258, 314976, 59886, 59414, 224040, 229377, 482764, 0, 418433, 121305, 47807, 407440, 51547, 530978], [394936, 119817, 217686, 306739, 288485, 190689, 294341, 379747, 441013, 90088, 174173, 110982, 90310, 84177, 533298, 382525, 302150, 391005, 424673, 382945, 528076, 367218, 227861, 556786, 159780, 293938, 342408, 258111, 359568, 367175, 228276, 429805, 317893, 418433, 0, 515064, 371904, 249637, 381509, 293301], [291140, 407585, 310387, 255114, 544788, 432588, 564878, 140257, 74111, 600610, 596319, 479964, 447455, 593082, 426186, 282778, 332965, 133626, 138867, 133870, 223497, 462586, 405170, 103608, 391112, 231168, 174094, 356656, 165204, 152072, 340846, 200778, 512855, 121305, 515064, 0, 164624, 450245, 136922, 573716], [293377, 280337, 155900, 197339, 473256, 338741, 491892, 39308, 100302, 461075, 483539, 361969, 294687, 454296, 464854, 278823, 284225, 34477, 170911, 52974, 311245, 430241, 324686, 247427, 279361, 78076, 90128, 286974, 23979, 38895, 177161, 233973, 455638, 47807, 371904, 164624, 0, 376916, 45412, 498907], [205417, 171576, 289533, 195959, 96874, 64095, 116277, 358628, 388712, 278672, 187375, 139306, 278510, 270683, 295413, 201018, 121772, 373979, 317471, 352657, 358451, 117601, 53055, 443322, 131548, 317319, 297872, 94168, 354255, 348532, 344487, 281930, 86038, 407440, 249637, 450245, 376916, 0, 356278, 124356], [253778, 280105, 173468, 167223, 453151, 324564, 472394, 6107, 64684, 468809, 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# Initialize Model
m = GEKKO(remote=False)
m.options.SOLVER = 1
m.options.IMODE = 3
# VARIABLES
print("Creating variables...")
# warehouse locations
warehouses_to_hexagon_vars = []
for dks_id in range(n_warehouses):
warehouses_to_hexagon_vars.append([m.Var(value=0, lb=0, ub=1, integer=True, name=f"dk_{dks_id}_{hex_id}")
for hex_id in df_aggreg["hex_id_basic"].unique()])
# hexagon assigned to warehouse
hexagon_to_warehouse_vars = []
for hex_id in df_aggreg["hex_id_basic"].unique():
hexagon_to_warehouse_vars.append([m.Var(value=0, lb=0, ub=1, integer=True, name=f"hx_{hex_id}_{dks_id}")
for dks_id in range(n_warehouses)])
# CONSTRAINTS
# A warehouse located only in one hexagon
print("Creating constraints...")
for dks_vars in warehouses_to_hexagon_vars:
m.Equation(m.sum(dks_vars) == 1)
# One hexagon contains at most one warehouse
for hex_id in df_aggreg["hex_id_basic"].unique():
m.Equation(m.sum([dks_vars[hex_id] for dks_vars in warehouses_to_hexagon_vars]) <= 1)
# One hexagon assigned only to one warehouse
for hex_vars in hexagon_to_warehouse_vars:
m.Equation(m.sum(hex_vars) == 1)
# WARM START
for dks_id in range(n_warehouses):
warehouses_to_hexagon_vars[dks_id][randint(0, len(warehouses_to_hexagon_vars[dks_id]) - 1)].value = 1
for hex_id in range(len(hexagon_to_warehouse_vars)):
hexagon_to_warehouse_vars[hex_id][randint(0, n_warehouses - 1)].value = 1
# Set objective function
print("Creating objective function...")
for wh_id in range(n_warehouses):
for hex_id_1 in df_aggreg["hex_id_basic"].unique():
for hex_id_2 in df_aggreg["hex_id_basic"].unique():
distance_hexagon_to_warehouse = int(distance_matrix[hex_id_1][hex_id_2])
demand_hexagon = df_aggreg.loc[df_aggreg["hex_id_basic"] == hex_id_2, "value"].values[0]
m.Obj(warehouses_to_hexagon_vars[wh_id][hex_id_1] *
hexagon_to_warehouse_vars[hex_id_2][wh_id] *
distance_hexagon_to_warehouse *
demand_hexagon)
# Solve simulation
m.solve()
I've implemented a parallel solution in which I run the same model n times but with a different initial solution each. Once all models have been solved, I take the solution with lowest objective value.
I've got a three pd.DataFrames:
df1 = pd.DataFrame({'var1': {0: 2210, 1: 2210, 2: 2210, 3: 2210, 4: 2210, 5: 2210, 6: 2210, 7: 2210, 8: 2210, 9: 2210, 10: 2210, 11: 2210, 12: 2210, 13: 2210, 14: 2210, 15: 2210, 16: 2210, 17: 2210, 18: 2210, 19: 2210, 20: 2210, 21: 2210}, 'var2': {0: 1, 1: 2, 2: 1, 3: 2, 4: 1, 5: 2, 6: 1, 7: 2, 8: 1, 9: 2, 10: 1, 11: 2, 12: 1, 13: 2, 14: 1, 15: 2, 16: 1, 17: 2, 18: 1, 19: 2, 20: 1, 21: 2}, 'var3': {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0, 10: 0, 11: 0, 12: 0, 13: 0, 14: 0, 15: 0, 16: 0, 17: 0, 18: 0, 19: 0, 20: 0, 21: 0}, 'var4': {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0, 10: 0, 11: 0, 12: 0, 13: 0, 14: 0, 15: 0, 16: 0, 17: 0, 18: 0, 19: 0, 20: 0, 21: 0}, 'var5': {0: '121160', 1: '20066', 2: ' 58621', 3: ' 201084', 4: ' 100180', 5: ' 74230', 6: ' 27789', 7: ' 66975', 8: ' 57410', 9: ' 49413', 10: ' 57112', 11: ' 19188', 12: ' 61366', 13: ' 27341', 14: ' 59859', 15: ' 173954', 16: ' 205651', 17: ' 54861', 18: ' 165809', 19: ' 60252', 20: ' 182156', 21: ' 82403'}})
df2 = pd.DataFrame({'var1': {349176: 2210, 349225: 2210, 349913: 2210, 350247: 2210, 350342: 2210, 350518: 2210}, 'var2': {349176: 2, 349225: 1, 349913: 1, 350247: 2, 350342: 1, 350518: 2}, 'var5': {349176: 58786.0, 349225: 37572.0, 349913: 103955.0, 350247: 19197.0, 350342: 14664.0, 350518: 75773.0}, 'var3': {349176: 19, 349225: 22, 349913: 56, 350247: 75, 350342: 80, 350518: 95}, 'var4': {349176: 8, 349225: 52, 349913: 42, 350247: 0, 350342: 50, 350518: 17}})
df3 = pd.DataFrame({'var1': {349175: 2210, 349224: 2210, 349912: 2210, 350246: 2210, 350341: 2210, 350517: 2210, 350521: 2210}, 'var2': {349175: 2, 349224: 1, 349912: 1, 350246: 2, 350341: 1, 350517: 2, 350521: 1}, 'var5': {349175: 19188.0, 349224: 205651.0, 349912: 59859.0, 350246: 27341.0, 350341: 165809.0, 350517: 19197.0, 350521: 61366.0}, 'var6': {349175: 19, 349224: 22, 349912: 56, 350246: 75, 350341: 80, 350517: 95, 350521: 95}, 'var7': {349175: 8, 349224: 52, 349912: 42, 350246: 0, 350341: 50, 350517: 17, 350521: 40}})
I need to stack df1 and df2 together, then join them by left join with df3 based on multiple variables: var1, var2, var5.
So I wrote:
pd.concat([df1, df2], axis = 0, sort = False).merge(df3, how = 'left', on = ['var1', 'var2', 'var5'])
but it doesn't find all the matching rows. Changing the type to outer join we can observe there's is for example two rows with the same values of var1, var2 and var3 - rows 11th and 28th, but they haven't been joined:
pd.concat([df1, df2], axis = 0, sort = False).merge(df3, how = 'outer', on = ['var1', 'var2', 'var5'])
I'm struggling to find a reason for that behaviour. I thought maybe data types are different within joining columns, but no - they are the same. I'm relatively new to Pandas, so maybe I'm missing something obvious here? What is the reason for that (unexpected) behaviour?
df1 = pd.DataFrame({'var1': {0: 2210, 1: 2210, 2: 2210, 3: 2210, 4: 2210, 5: 2210, 6: 2210, 7: 2210, 8: 2210, 9: 2210, 10: 2210, 11: 2210, 12: 2210, 13: 2210, 14: 2210, 15: 2210, 16: 2210, 17: 2210, 18: 2210, 19: 2210, 20: 2210, 21: 2210}, 'var2': {0: 1, 1: 2, 2: 1, 3: 2, 4: 1, 5: 2, 6: 1, 7: 2, 8: 1, 9: 2, 10: 1, 11: 2, 12: 1, 13: 2, 14: 1, 15: 2, 16: 1, 17: 2, 18: 1, 19: 2, 20: 1, 21: 2}, 'var3': {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0, 10: 0, 11: 0, 12: 0, 13: 0, 14: 0, 15: 0, 16: 0, 17: 0, 18: 0, 19: 0, 20: 0, 21: 0}, 'var4': {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0, 10: 0, 11: 0, 12: 0, 13: 0, 14: 0, 15: 0, 16: 0, 17: 0, 18: 0, 19: 0, 20: 0, 21: 0}, 'var5': {0: '121160', 1: '20066', 2: ' 58621', 3: ' 201084', 4: ' 100180', 5: ' 74230', 6: ' 27789', 7: ' 66975', 8: ' 57410', 9: ' 49413', 10: ' 57112', 11: ' 19188', 12: ' 61366', 13: ' 27341', 14: ' 59859', 15: ' 173954', 16: ' 205651', 17: ' 54861', 18: ' 165809', 19: ' 60252', 20: ' 182156', 21: ' 82403'}})
df2 = pd.DataFrame({'var1': {349176: 2210, 349225: 2210, 349913: 2210, 350247: 2210, 350342: 2210, 350518: 2210}, 'var2': {349176: 2, 349225: 1, 349913: 1, 350247: 2, 350342: 1, 350518: 2}, 'var5': {349176: 58786.0, 349225: 37572.0, 349913: 103955.0, 350247: 19197.0, 350342: 14664.0, 350518: 75773.0}, 'var3': {349176: 19, 349225: 22, 349913: 56, 350247: 75, 350342: 80, 350518: 95}, 'var4': {349176: 8, 349225: 52, 349913: 42, 350247: 0, 350342: 50, 350518: 17}})
df3 = pd.DataFrame({'var1': {349175: 2210, 349224: 2210, 349912: 2210, 350246: 2210, 350341: 2210, 350517: 2210, 350521: 2210}, 'var2': {349175: 2, 349224: 1, 349912: 1, 350246: 2, 350341: 1, 350517: 2, 350521: 1}, 'var5': {349175: 19188.0, 349224: 205651.0, 349912: 59859.0, 350246: 27341.0, 350341: 165809.0, 350517: 19197.0, 350521: 61366.0}, 'var6': {349175: 19, 349224: 22, 349912: 56, 350246: 75, 350341: 80, 350517: 95, 350521: 95}, 'var7': {349175: 8, 349224: 52, 349912: 42, 350246: 0, 350341: 50, 350517: 17, 350521: 40}})
pd.concat([df1, df2], axis = 0).dtypes
results in
var1 int64
var2 int64
var3 int64
var4 int64
var5 object
dtype: object
As you can see after the concat the var5 is an object. If you merge at this point you will get no results as var5 in df3 is a float.
Here is what I would recommend:
df1['var5'] = df1['var5'].astype(float)
df2['var5'] = df2['var5'].astype(float)
df3['var5'] = df3['var5'].astype(float)
pd.concat([df1, df2], axis = 0).merge(df3, how = 'left', on = ['var1', 'var2', 'var5'])
This will produce the following DataFrame:
var1 var2 var3 var4 var5 var6 var7
0 2210 1 0 0 121160.0 NaN NaN
1 2210 2 0 0 20066.0 NaN NaN
2 2210 1 0 0 58621.0 NaN NaN
3 2210 2 0 0 201084.0 NaN NaN
4 2210 1 0 0 100180.0 NaN NaN
5 2210 2 0 0 74230.0 NaN NaN
6 2210 1 0 0 27789.0 NaN NaN
7 2210 2 0 0 66975.0 NaN NaN
8 2210 1 0 0 57410.0 NaN NaN
9 2210 2 0 0 49413.0 NaN NaN
10 2210 1 0 0 57112.0 NaN NaN
11 2210 2 0 0 19188.0 19.0 8.0
12 2210 1 0 0 61366.0 95.0 40.0
13 2210 2 0 0 27341.0 75.0 0.0
14 2210 1 0 0 59859.0 56.0 42.0
15 2210 2 0 0 173954.0 NaN NaN
16 2210 1 0 0 205651.0 22.0 52.0
17 2210 2 0 0 54861.0 NaN NaN
18 2210 1 0 0 165809.0 80.0 50.0
19 2210 2 0 0 60252.0 NaN NaN
20 2210 1 0 0 182156.0 NaN NaN
21 2210 2 0 0 82403.0 NaN NaN
22 2210 2 19 8 58786.0 NaN NaN
23 2210 1 22 52 37572.0 NaN NaN
24 2210 1 56 42 103955.0 NaN NaN
25 2210 2 75 0 19197.0 95.0 17.0
26 2210 1 80 50 14664.0 NaN NaN
27 2210 2 95 17 75773.0 NaN NaN
When I ran your code on my computer, then used df#.dtypes to get the types, the dtype of the var5 column in df1 is object, whereas in df2 and df3 it's float64. The concat runs fine with this (and after the concat, the dtype is object), but when I tried to run the merge (outer or left), I got a ValueError:
ValueError: You are trying to merge on object and float64 columns. If you wish to proceed you should use pd.concat
I'd suggest double checking the types again (I know you already checked that). If they really are the same on your computer, I'm not sure what's going on.