Task¶
Consider the signal $x$ given below. Plot autocorrelation for lags 1 to 10. Use autocorrelation for lag 1 to decide if this signal is random.
In [2]:
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline
In [3]:
x = np.array([-213, -564, -35, -15, 141, 115, -420, -360,
203, -338, -431, 194, -220, -513, 154, -125,
-559, 92, -21, -579, -52, 99, -543, -175,
162, -457, -346, 204, -300, -474, 164, -107,
-572, -8, 83, -541, -224, 180, -420, -374,
201, -236, -531, 83, 27, -564, -112, 131,
-507, -254, 199, -311, -495, 143, -46, -579,
-90, 136, -472, -338, 202, -287, -477, 169,
-124, -568, 17, 48, -568, -135, 162, -430,
-422, 172, -74, -577, -13, 92, -534, -243,
194, -355, -465, 156, -81, -578, -64, 139,
-449, -384, 193, -198, -538, 110, -44, -577,
-6, 66, -552, -164, 161, -460, -344, 205, -281,
-504, 134, -28, -576, -118, 156, -437, -381,
200, -220, -540, 83, 11, -568, -160, 172, -414,
-408, 188, -125, -572, -32, 139, -492, -321,
205, -262, -504, 142, -83, -574, 0, 48, -571,
-106, 137, -501, -266, 190, -391, -406, 194,
-186, -553, 83, -13, -577, -49, 103, -515,
-280, 201, 300, -506, 131, -45, -578, -80,
138, -462, -361, 201, -211, -554, 32, 74, -533,
-235, 187, -372, -442, 182, -147, -566, 25,
68, -535, -244, 194, -351, -463, 174, -125, -570,
15, 72, -550, -190, 172, -424, -385, 198, -218, -536, 96])
In [4]:
plt.figure(figsize=(20,5))
plt.plot(x)
plt.plot(x, '.r')
plt.title('x vs. time')
plt.ylabel('x')
plt.xlabel('time')
Out[4]:
Text(0.5, 0, 'time')
In [ ]:
In [5]:
y = x*2-190
In [6]:
plt.plot(y)
Out[6]:
[<matplotlib.lines.Line2D at 0x115814610>]
In [7]:
y
Out[7]:
array([ -616, -1318, -260, -220, 92, 40, -1030, -910, 216,
-866, -1052, 198, -630, -1216, 118, -440, -1308, -6,
-232, -1348, -294, 8, -1276, -540, 134, -1104, -882,
218, -790, -1138, 138, -404, -1334, -206, -24, -1272,
-638, 170, -1030, -938, 212, -662, -1252, -24, -136,
-1318, -414, 72, -1204, -698, 208, -812, -1180, 96,
-282, -1348, -370, 82, -1134, -866, 214, -764, -1144,
148, -438, -1326, -156, -94, -1326, -460, 134, -1050,
-1034, 154, -338, -1344, -216, -6, -1258, -676, 198,
-900, -1120, 122, -352, -1346, -318, 88, -1088, -958,
196, -586, -1266, 30, -278, -1344, -202, -58, -1294,
-518, 132, -1110, -878, 220, -752, -1198, 78, -246,
-1342, -426, 122, -1064, -952, 210, -630, -1270, -24,
-168, -1326, -510, 154, -1018, -1006, 186, -440, -1334,
-254, 88, -1174, -832, 220, -714, -1198, 94, -356,
-1338, -190, -94, -1332, -402, 84, -1192, -722, 190,
-972, -1002, 198, -562, -1296, -24, -216, -1344, -288,
16, -1220, -750, 212, 410, -1202, 72, -280, -1346,
-350, 86, -1114, -912, 212, -612, -1298, -126, -42,
-1256, -660, 184, -934, -1074, 174, -484, -1322, -140,
-54, -1260, -678, 198, -892, -1116, 158, -440, -1330,
-160, -46, -1290, -570, 154, -1038, -960, 206, -626,
-1262, 2])
In [8]:
for i in y:
print(i)
-616 -1318 -260 -220 92 40 -1030 -910 216 -866 -1052 198 -630 -1216 118 -440 -1308 -6 -232 -1348 -294 8 -1276 -540 134 -1104 -882 218 -790 -1138 138 -404 -1334 -206 -24 -1272 -638 170 -1030 -938 212 -662 -1252 -24 -136 -1318 -414 72 -1204 -698 208 -812 -1180 96 -282 -1348 -370 82 -1134 -866 214 -764 -1144 148 -438 -1326 -156 -94 -1326 -460 134 -1050 -1034 154 -338 -1344 -216 -6 -1258 -676 198 -900 -1120 122 -352 -1346 -318 88 -1088 -958 196 -586 -1266 30 -278 -1344 -202 -58 -1294 -518 132 -1110 -878 220 -752 -1198 78 -246 -1342 -426 122 -1064 -952 210 -630 -1270 -24 -168 -1326 -510 154 -1018 -1006 186 -440 -1334 -254 88 -1174 -832 220 -714 -1198 94 -356 -1338 -190 -94 -1332 -402 84 -1192 -722 190 -972 -1002 198 -562 -1296 -24 -216 -1344 -288 16 -1220 -750 212 410 -1202 72 -280 -1346 -350 86 -1114 -912 212 -612 -1298 -126 -42 -1256 -660 184 -934 -1074 174 -484 -1322 -140 -54 -1260 -678 198 -892 -1116 158 -440 -1330 -160 -46 -1290 -570 154 -1038 -960 206 -626 -1262 2
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