Question

Python:

Implement a function called monthlyAmortization() that takes the following parameters:

the principal amount of the loan (p)

the interest rate, or annual rate (r)

the term of the loan in months (t)

the payment amount each period (monthlyPayment)

The function prints the amortization table to a file called amoritizedLoan.txt.

At the end of this file, the fucntion prints the total amount of interest paid for the loan.

The output needs to be nicely formatted as shown below.

The example has the following parameters: for p = 100,000; r = 6% yearly; monthlyPayment = 599.55; t = 30 years, or 360 months:

>>> monthlyAmortization(100000, .06, 360, 599.55)

>>>

The output file amortizedLoan.txt:

Your amortized loan of $100,000.00 for 360 months at 6.0% annual interest rate.

Month    Principal       Interest Payment     Principal Payment    Ending Principal   

    1    $100,000.00          $500.00               $99.55              $99,900.45          

    2    $99,900.45            $499.50               $100.05            $99,800.40          

    3    $99,800.40            $499.00               $100.55            $99,699.85          

    ………………………………………………………………..

358    $1,781.33              $8.91                  $590.64             $1,190.69           

359    $1,190.69              $5.95                 $593.60             $597.09             

360    $597.09                 $2.99                  $596.56             $0.53               

The total amount of interest paid: $115,838.53

-------

The following formulas are helpful:

Remember to convert the annually interest rate to the monthly interest rate: .06/12

Month 1

monthlyInterestPayment = p*r

principalPayment = ($599.55 payment - $500 interest = $99.55 principal payment).

endingPrinciple = principle – principalPayment = 100,000 – 99.55 = 99,900.45

Month 2

principal = last month’s endingPrincipal = 99,900.45

…..

This example was taken from How to Calculate Amortization, October 1, 2019,

https://www.vertex42.com/ExcelArticles/amortization-calculation.html

Answer 1

def monthlyAmortization(p, r, months, mp):

# opening the file and writing the header

f = open("amoritizedLoan.txt", "w")

f.write("Month Principal Interest Payment Principal Payment Ending Principal\n")

r = r / 12

# looping for months number of times

for i in range(months):

# updating the values

pp = mp - p*r

ep = p - pp

# writing to file

f.write(str(i+1)+ "\t"+ str(round(p,2))+str(round( p*r,2)) + "\t"+ str(round(pp,2))+"\t"+ str(round(ep,2)) + "\n")

p= ep

# done with writing, closing the file

f.close()

monthlyAmortization(100000, .06, 360, 599.55)

''' OUTPUT file:

Month Principal Interest Payment Principal Payment Ending Principal
1   100000500.0   99.55   99900.45
2   99900.45499.5   100.05   99800.4
3   99800.4499.0   100.55   99699.85
4   99699.85498.5   101.05   99598.8
5   99598.8497.99   101.56   99497.25
6   99497.25497.49   102.06   99395.18
7   99395.18496.98   102.57   99292.61
8   99292.61496.46   103.09   99189.52
9   99189.52495.95   103.6   99085.92
10   99085.92495.43   104.12   98981.8
11   98981.8494.91   104.64   98877.16
12   98877.16494.39   105.16   98771.99
13   98771.99493.86   105.69   98666.3
14   98666.3493.33   106.22   98560.09
15   98560.09492.8   106.75   98453.34
16   98453.34492.27   107.28   98346.05
17   98346.05491.73   107.82   98238.23
18   98238.23491.19   108.36   98129.87
19   98129.87490.65   108.9   98020.97
20   98020.97490.1   109.45   97911.53
21   97911.53489.56   109.99   97801.54
22   97801.54489.01   110.54   97690.99
23   97690.99488.45   111.1   97579.9
24   97579.9487.9   111.65   97468.25
25   97468.25487.34   112.21   97356.04
26   97356.04486.78   112.77   97243.27
27   97243.27486.22   113.33   97129.94
28   97129.94485.65   113.9   97016.04
29   97016.04485.08   114.47   96901.57
30   96901.57484.51   115.04   96786.52
31   96786.52483.93   115.62   96670.91
32   96670.91483.35   116.2   96554.71
33   96554.71482.77   116.78   96437.94
34   96437.94482.19   117.36   96320.57
35   96320.57481.6   117.95   96202.63
36   96202.63481.01   118.54   96084.09
37   96084.09480.42   119.13   95964.96
38   95964.96479.82   119.73   95845.24
39   95845.24479.23   120.32   95724.91
40   95724.91478.62   120.93   95603.99
41   95603.99478.02   121.53   95482.46
42   95482.46477.41   122.14   95360.32
43   95360.32476.8   122.75   95237.57
44   95237.57476.19   123.36   95114.21
45   95114.21475.57   123.98   94990.23
46   94990.23474.95   124.6   94865.63
47   94865.63474.33   125.22   94740.41
48   94740.41473.7   125.85   94614.56
49   94614.56473.07   126.48   94488.08
50   94488.08472.44   127.11   94360.97
51   94360.97471.8   127.75   94233.23
52   94233.23471.17   128.38   94104.85
53   94104.85470.52   129.03   93975.82
54   93975.82469.88   129.67   93846.15
55   93846.15469.23   130.32   93715.83
56   93715.83468.58   130.97   93584.86
57   93584.86467.92   131.63   93453.23
58   93453.23467.27   132.28   93320.95
59   93320.95466.6   132.95   93188.0
60   93188.0465.94   133.61   93054.39
61   93054.39465.27   134.28   92920.12
62   92920.12464.6   134.95   92785.17
63   92785.17463.93   135.62   92649.54
64   92649.54463.25   136.3   92513.24
65   92513.24462.57   136.98   92376.26
66   92376.26461.88   137.67   92238.59
67   92238.59461.19   138.36   92100.23
68   92100.23460.5   139.05   91961.18
69   91961.18459.81   139.74   91821.44
70   91821.44459.11   140.44   91680.99
71   91680.99458.4   141.15   91539.85
72   91539.85457.7   141.85   91398.0
73   91398.0456.99   142.56   91255.44
74   91255.44456.28   143.27   91112.17
75   91112.17455.56   143.99   90968.18
76   90968.18454.84   144.71   90823.47
77   90823.47454.12   145.43   90678.03
78   90678.03453.39   146.16   90531.87
79   90531.87452.66   146.89   90384.98
80   90384.98451.92   147.63   90237.36
81   90237.36451.19   148.36   90089.0
82   90089.0450.44   149.11   89939.89
83   89939.89449.7   149.85   89790.04
84   89790.04448.95   150.6   89639.44
85   89639.44448.2   151.35   89488.09
86   89488.09447.44   152.11   89335.98
87   89335.98446.68   152.87   89183.11
88   89183.11445.92   153.63   89029.47
89   89029.47445.15   154.4   88875.07
90   88875.07444.38   155.17   88719.9
91   88719.9443.6   155.95   88563.95
92   88563.95442.82   156.73   88407.22
93   88407.22442.04   157.51   88249.7
94   88249.7441.25   158.3   88091.4
95   88091.4440.46   159.09   87932.31
96   87932.31439.66   159.89   87772.42
97   87772.42438.86   160.69   87611.73
98   87611.73438.06   161.49   87450.24
99   87450.24437.25   162.3   87287.94
100   87287.94436.44   163.11   87124.83
101   87124.83435.62   163.93   86960.9
102   86960.9434.8   164.75   86796.16
103   86796.16433.98   165.57   86630.59
104   86630.59433.15   166.4   86464.19
105   86464.19432.32   167.23   86296.96
106   86296.96431.48   168.07   86128.9
107   86128.9430.64   168.91   85959.99
108   85959.99429.8   169.75   85790.24
109   85790.24428.95   170.6   85619.64
110   85619.64428.1   171.45   85448.19
111   85448.19427.24   172.31   85275.88
112   85275.88426.38   173.17   85102.71
113   85102.71425.51   174.04   84928.68
114   84928.68424.64   174.91   84753.77
115   84753.77423.77   175.78   84577.99
116   84577.99422.89   176.66   84401.33
117   84401.33422.01   177.54   84223.79
118   84223.79421.12   178.43   84045.35
119   84045.35420.23   179.32   83866.03
120   83866.03419.33   180.22   83685.81
121   83685.81418.43   181.12   83504.69
122   83504.69417.52   182.03   83322.66
123   83322.66416.61   182.94   83139.73
124   83139.73415.7   183.85   82955.88
125   82955.88414.78   184.77   82771.1
126   82771.1413.86   185.69   82585.41
127   82585.41412.93   186.62   82398.79
128   82398.79411.99   187.56   82211.23
129   82211.23411.06   188.49   82022.74
130   82022.74410.11   189.44   81833.3
131   81833.3409.17   190.38   81642.92
132   81642.92408.21   191.34   81451.58
133   81451.58407.26   192.29   81259.29
134   81259.29406.3   193.25   81066.04
135   81066.04405.33   194.22   80871.82
136   80871.82404.36   195.19   80676.63
137   80676.63403.38   196.17   80480.46
138   80480.46402.4   197.15   80283.31
139   80283.31401.42   198.13   80085.18
140   80085.18400.43   199.12   79886.05
141   79886.05399.43   200.12   79685.93
142   79685.93398.43   201.12   79484.81
143   79484.81397.42   202.13   79282.69
144   79282.69396.41   203.14   79079.55
145   79079.55395.4   204.15   78875.4
146   78875.4394.38   205.17   78670.23
147   78670.23393.35   206.2   78464.03
148   78464.03392.32   207.23   78256.8
149   78256.8391.28   208.27   78048.53
150   78048.53390.24   209.31   77839.22
151   77839.22389.2   210.35   77628.87
152   77628.87388.14   211.41   77417.46
153   77417.46387.09   212.46   77205.0
154   77205.0386.03   213.52   76991.48
155   76991.48384.96   214.59   76776.88
156   76776.88383.88   215.67   76561.22
157   76561.22382.81   216.74   76344.47
158   76344.47381.72   217.83   76126.65
159   76126.65380.63   218.92   75907.73
160   75907.73379.54   220.01   75687.72
161   75687.72378.44   221.11   75466.61
162   75466.61377.33   222.22   75244.39
163   75244.39376.22   223.33   75021.06
164   75021.06375.11   224.44   74796.62
165   74796.62373.98   225.57   74571.05
166   74571.05372.86   226.69   74344.36
167   74344.36371.72   227.83   74116.53
168   74116.53370.58   228.97   73887.56
169   73887.56369.44   230.11   73657.45
170   73657.45368.29   231.26   73426.19
171   73426.19367.13   232.42   73193.77
172   73193.77365.97   233.58   72960.19
173   72960.19364.8   234.75   72725.44
174   72725.44363.63   235.92   72489.51
175   72489.51362.45   237.1   72252.41
176   72252.41361.26   238.29   72014.12
177   72014.12360.07   239.48   71774.64
178   71774.64358.87   240.68   71533.97
179   71533.97357.67   241.88   71292.09
180   71292.09356.46   243.09   71049.0
181   71049.0355.24   244.31   70804.69
182   70804.69354.02   245.53   70559.17
183   70559.17352.8   246.75   70312.41
184   70312.41351.56   247.99   70064.42
185   70064.42350.32   249.23   69815.2
186   69815.2349.08   250.47   69564.72
187   69564.72347.82   251.73   69313.0
188   69313.0346.56   252.99   69060.01
189   69060.01345.3   254.25   68805.76
190   68805.76344.03   255.52   68550.24
191   68550.24342.75   256.8   68293.44
192   68293.44341.47   258.08   68035.36
193   68035.36340.18   259.37   67775.98
194   67775.98338.88   260.67   67515.31
195   67515.31337.58   261.97   67253.34
196   67253.34336.27   263.28   66990.06
197   66990.06334.95   264.6   66725.46
198   66725.46333.63   265.92   66459.53
199   66459.53332.3   267.25   66192.28
200   66192.28330.96   268.59   65923.69
201   65923.69329.62   269.93   65653.76
202   65653.76328.27   271.28   65382.48
203   65382.48326.91   272.64   65109.84
204   65109.84325.55   274.0   64835.84
205   64835.84324.18   275.37   64560.47
206   64560.47322.8   276.75   64283.72
207   64283.72321.42   278.13   64005.59
208   64005.59320.03   279.52   63726.07
209   63726.07318.63   280.92   63445.15
210   63445.15317.23   282.32   63162.83
211   63162.83315.81   283.74   62879.09
212   62879.09314.4   285.15   62593.94
213   62593.94312.97   286.58   62307.36
214   62307.36311.54   288.01   62019.34
215   62019.34310.1   289.45   61729.89
216   61729.89308.65   290.9   61438.99
217   61438.99307.19   292.36   61146.63
218   61146.63305.73   293.82   60852.82
219   60852.82304.26   295.29   60557.53
220   60557.53302.79   296.76   60260.77
221   60260.77301.3   298.25   59962.52
222   59962.52299.81   299.74   59662.79
223   59662.79298.31   301.24   59361.55
224   59361.55296.81   302.74   59058.81
225   59058.81295.29   304.26   58754.55
226   58754.55293.77   305.78   58448.77
227   58448.77292.24   307.31   58141.47
228   58141.47290.71   308.84   57832.63
229   57832.63289.16   310.39   57522.24
230   57522.24287.61   311.94   57210.3
231   57210.3286.05   313.5   56896.8
232   56896.8284.48   315.07   56581.74
233   56581.74282.91   316.64   56265.09
234   56265.09281.33   318.22   55946.87
235   55946.87279.73   319.82   55627.05
236   55627.05278.14   321.41   55305.64
237   55305.64276.53   323.02   54982.62
238   54982.62274.91   324.64   54657.98
239   54657.98273.29   326.26   54331.72
240   54331.72271.66   327.89   54003.83
241   54003.83270.02   329.53   53674.3
242   53674.3268.37   331.18   53343.12
243   53343.12266.72   332.83   53010.29
244   53010.29265.05   334.5   52675.79
245   52675.79263.38   336.17   52339.62
246   52339.62261.7   337.85   52001.76
247   52001.76260.01   339.54   51662.22
248   51662.22258.31   341.24   51320.98
249   51320.98256.6   342.95   50978.04
250   50978.04254.89   344.66   50633.38
251   50633.38253.17   346.38   50287.0
252   50287.0251.43   348.12   49938.88
253   49938.88249.69   349.86   49589.02
254   49589.02247.95   351.6   49237.42
255   49237.42246.19   353.36   48884.06
256   48884.06244.42   355.13   48528.93
257   48528.93242.64   356.91   48172.02
258   48172.02240.86   358.69   47813.33
259   47813.33239.07   360.48   47452.85
260   47452.85237.26   362.29   47090.56
261   47090.56235.45   364.1   46726.47
262   46726.47233.63   365.92   46360.55
263   46360.55231.8   367.75   45992.8
264   45992.8229.96   369.59   45623.21
265   45623.21228.12   371.43   45251.78
266   45251.78226.26   373.29   44878.49
267   44878.49224.39   375.16   44503.33
268   44503.33222.52   377.03   44126.3
269   44126.3220.63   378.92   43747.38
270   43747.38218.74   380.81   43366.57
271   43366.57216.83   382.72   42983.85
272   42983.85214.92   384.63   42599.22
273   42599.22213.0   386.55   42212.67
274   42212.67211.06   388.49   41824.18
275   41824.18209.12   390.43   41433.75
276   41433.75207.17   392.38   41041.37
277   41041.37205.21   394.34   40647.03
278   40647.03203.24   396.31   40250.71
279   40250.71201.25   398.3   39852.41
280   39852.41199.26   400.29   39452.13
281   39452.13197.26   402.29   39049.84
282   39049.84195.25   404.3   38645.54
283   38645.54193.23   406.32   38239.21
284   38239.21191.2   408.35   37830.86
285   37830.86189.15   410.4   37420.46
286   37420.46187.1   412.45   37008.02
287   37008.02185.04   414.51   36593.51
288   36593.51182.97   416.58   36176.92
289   36176.92180.88   418.67   35758.26
290   35758.26178.79   420.76   35337.5
291   35337.5176.69   422.86   34914.64
292   34914.64174.57   424.98   34489.66
293   34489.66172.45   427.1   34062.56
294   34062.56170.31   429.24   33633.32
295   33633.32168.17   431.38   33201.94
296   33201.94166.01   433.54   32768.4
297   32768.4163.84   435.71   32332.69
298   32332.69161.66   437.89   31894.8
299   31894.8159.47   440.08   31454.73
300   31454.73157.27   442.28   31012.45
301   31012.45155.06   444.49   30567.96
302   30567.96152.84   446.71   30121.25
303   30121.25150.61   448.94   29672.31
304   29672.31148.36   451.19   29221.12
305   29221.12146.11   453.44   28767.68
306   28767.68143.84   455.71   28311.96
307   28311.96141.56   457.99   27853.97
308   27853.97139.27   460.28   27393.69
309   27393.69136.97   462.58   26931.11
310   26931.11134.66   464.89   26466.22
311   26466.22132.33   467.22   25999.0
312   25999.0129.99   469.56   25529.44
313   25529.44127.65   471.9   25057.54
314   25057.54125.29   474.26   24583.28
315   24583.28122.92   476.63   24106.65
316   24106.65120.53   479.02   23627.63
317   23627.63118.14   481.41   23146.22
318   23146.22115.73   483.82   22662.4
319   22662.4113.31   486.24   22176.16
320   22176.16110.88   488.67   21687.49
321   21687.49108.44   491.11   21196.38
322   21196.38105.98   493.57   20702.81
323   20702.81103.51   496.04   20206.77
324   20206.77101.03   498.52   19708.26
325   19708.2698.54   501.01   19207.25
326   19207.2596.04   503.51   18703.74
327   18703.7493.52   506.03   18197.7
328   18197.790.99   508.56   17689.14
329   17689.1488.45   511.1   17178.04
330   17178.0485.89   513.66   16664.38
331   16664.3883.32   516.23   16148.15
332   16148.1580.74   518.81   15629.34
333   15629.3478.15   521.4   15107.94
334   15107.9475.54   524.01   14583.93
335   14583.9372.92   526.63   14057.3
336   14057.370.29   529.26   13528.03
337   13528.0367.64   531.91   12996.12
338   12996.1264.98   534.57   12461.56
339   12461.5662.31   537.24   11924.31
340   11924.3159.62   539.93   11384.38
341   11384.3856.92   542.63   10841.76
342   10841.7654.21   545.34   10296.42
343   10296.4251.48   548.07   9748.35
344   9748.3548.74   550.81   9197.54
345   9197.5445.99   553.56   8643.98
346   8643.9843.22   556.33   8087.65
347   8087.6540.44   559.11   7528.53
348   7528.5337.64   561.91   6966.63
349   6966.6334.83   564.72   6401.91
350   6401.9132.01   567.54   5834.37
351   5834.3729.17   570.38   5263.99
352   5263.9926.32   573.23   4690.76
353   4690.7623.45   576.1   4114.67
354   4114.6720.57   578.98   3535.69
355   3535.6917.68   581.87   2953.82
356   2953.8214.77   584.78   2369.04
357   2369.0411.85   587.7   1781.33
358   1781.338.91   590.64   1190.69
359   1190.695.95   593.6   597.09
360   597.092.99   596.56   0.53

'''