我有一份数据列表（两列），我想在gnuplot中绘制仅具有局部最大值的第二列的值。
为此，我想查看第i行的第二列是否大于第（i-1）和（i + 1）行。
2个回答
6
这是可以做到的，而我也无聊到足够做这件事。我生成了以下一组随机数据：
5191
29375
23222
32118
3185
32355
17173
8734
28850
20811
5956
6950
28560
25770
4630
28272
10035
7209
19428
26187
30784
20326
12865
23288
20924
把数值根据它们在列表中的位置绘制出来，看起来像这样：
从上面的图表中，您可以立即发现局部最大值。现在，当我识别到最大值时，我可以处理数据点并将两个先前的值（x和y坐标）存储在临时变量中，然后绘制数据点：
# Select the columns of your data file that contain x and y data
# (usually 1 and 2 respectively)
xcolumn=0
ycolumn=1
plot "data" u (column(xcolumn)):(column(ycolumn)) w l, \
"data" u (column(0)==0 ? (last2y=column(ycolumn), \
last2x=column(xcolumn), 1/0) : column(0)==1 ? (lasty=column(ycolumn), \
lastx=column(xcolumn), 1/0) : lastx) \
: \
( column(0) < 2 ? 1/0 : (last2y < lasty && \
column(ycolumn) < lasty) ? (value=lasty, last2y=lasty, last2x=lastx, \
lasty=column(ycolumn), lastx=column(xcolumn), value) : (last2y=lasty, \
last2x=lastx, lasty=column(ycolumn), lastx=column(xcolumn), 1/0)) pt 7
- Miguel
7
6
一个简单的gnuplot峰值查找器
比较连续的3个数据点是寻找最大值/峰值的一种简单方法。
if y(i-1) < y(i) > y(i+1) then you have a maximum/peak at x(i).
然而，如果您有嘈杂的曲线（通常是实验光谱），则会得到太多的“峰”。下面的脚本基本上为每个峰计算一个特定数字，该数字是峰的“独立性”的度量（参见地形突出度）。请注意，高峰值强度并不一定意味着突出度高。对于脚本，需要gnuplot>=5.2，因为它使用数据块和
plot ... with table。通过一些调整，它可能可以在旧版本中运行。您可以提供“阈值”以仅显示一定数量的峰值。不幸的是，gnuplot没有易于内部排序数据块的功能，否则可以轻松显示前N个最突出的峰。因此，在这里进行了不同的处理：
Threshold=100表示显示所有峰，Threshold=0表示仅显示全局最大值。请注意，阈值值和显示的峰数在0和100之间不是线性的，因为它取决于光谱形状。欢迎评论和改进。 数据：
SO28173128.dat
# x y
6.02 3.33
9.59 4.03
9.59 4.03
9.59 4.03
9.83 3.66
10.58 3.22
10.62 3.85
11.32 2.33
11.53 3.67
11.88 3.27
13.28 3.97
13.42 4.35
14.56 2.99
14.75 3.50
15.23 3.91
15.59 3.58
16.56 3.85
16.70 4.49
16.97 3.98
17.23 4.49
17.37 3.73
17.90 4.24
17.93 4.91
18.80 4.23
18.83 4.64
20.37 3.59
20.48 3.99
21.70 3.19
22.29 4.36
22.41 3.38
23.34 5.04
23.41 5.38
24.38 4.71
24.58 4.96
25.40 5.13
25.41 4.70
26.20 4.21
26.36 4.84
26.55 4.11
26.79 4.73
27.02 4.13
27.54 4.51
27.55 5.17
28.08 5.42
28.33 4.97
28.61 5.17
29.06 5.10
29.12 4.26
29.61 3.61
30.03 4.84
30.58 5.30
30.68 4.72
31.21 5.82
31.99 5.83
32.58 6.56
33.03 6.23
33.51 6.79
33.73 8.88
34.00 7.85
34.17 9.82
34.32 11.24
34.55 10.78
34.85 12.58
35.14 13.84
35.50 18.07
35.85 18.40
36.55 30.70
36.75 29.27
37.16 28.78
38.15 18.93
38.29 20.52
38.83 14.96
39.63 11.39
40.17 8.67
40.48 9.22
40.88 9.75
40.95 8.77
41.45 10.86
41.58 10.33
41.84 11.12
42.51 12.83
43.33 15.09
43.43 14.20
43.63 14.56
44.22 14.76
44.92 12.58
45.71 9.40
45.98 9.84
47.03 7.01
47.53 7.15
47.95 5.48
48.08 6.21
48.56 4.51
48.64 5.11
49.14 3.69
49.31 4.27
49.86 4.71
50.14 4.13
50.33 5.83
50.37 5.36
51.00 4.60
51.37 4.75
52.00 4.91
52.01 4.34
54.28 3.83
54.46 4.33
54.83 3.19
55.58 5.30
55.86 4.95
55.92 6.48
56.40 5.89
56.59 5.16
57.56 5.96
57.64 5.21
58.31 5.36
58.38 6.08
58.92 5.84
59.00 5.28
59.57 5.96
59.94 5.37
61.31 6.07
61.32 6.78
61.96 7.34
62.37 6.89
63.14 9.45
63.54 9.51
63.80 11.03
63.93 11.56
64.17 11.12
64.84 12.38
65.14 16.28
65.64 18.07
66.22 19.06
66.42 17.70
66.56 18.40
67.10 17.20
67.24 18.00
67.77 16.82
68.04 15.80
68.15 16.88
68.43 14.98
68.86 16.28
69.33 16.55
70.43 29.11
70.93 48.16
71.62 58.09
72.01 66.42
72.43 73.37
72.79 76.74
72.84 81.24
73.07 79.85
73.15 72.04
73.32 74.49
73.58 61.26
73.71 65.36
73.98 51.60
73.98 58.75
74.25 52.93
74.53 39.70
74.90 34.01
75.18 34.80
76.67 23.29
77.05 23.82
77.15 20.94
77.27 27.13
77.52 25.20
77.70 29.76
78.17 29.96
78.36 33.33
78.73 37.05
78.86 34.67
79.03 39.90
79.38 39.70
79.59 40.62
79.88 39.17
80.59 36.52
80.60 33.61
81.26 27.53
81.67 23.69
82.07 23.69
82.90 15.37
83.94 14.04
84.25 14.42
85.01 11.26
85.22 12.18
85.77 11.19
85.89 9.97
86.46 10.72
86.56 11.78
87.06 10.56
87.19 11.53
87.74 9.60
87.89 10.64
88.30 8.74
88.56 9.27
88.98 8.08
89.25 8.70
90.12 9.15
90.14 8.34
90.99 9.59
91.06 8.86
91.72 9.01
91.74 8.48
92.43 7.68
92.48 8.34
93.15 7.68
93.54 8.34
93.72 7.61
94.20 8.00
94.39 8.64
94.82 7.83
95.00 8.40
95.43 6.77
95.66 7.39
95.81 5.44
95.84 6.25
96.53 7.70
96.55 6.70
97.22 9.14
97.47 8.13
97.53 6.75
98.57 7.83
98.85 7.40
98.92 8.45
99.35 8.25
99.40 7.77
100.04 8.33
100.14 7.91
101.00 8.30
101.04 7.80
101.94 7.48
102.02 8.20
102.53 6.56
102.58 7.84
103.23 7.75
103.38 6.82
103.39 8.93
103.75 8.60
104.05 9.26
104.30 8.14
104.55 8.56
104.85 7.15
105.17 10.09
105.21 8.41
105.52 11.78
105.80 10.00
105.92 10.86
106.11 9.54
106.31 9.93
106.86 10.99
107.20 10.88
107.42 12.05
107.62 10.33
107.80 11.16
108.39 9.90
108.79 12.25
109.08 11.85
109.46 13.77
109.73 13.42
109.96 15.16
111.02 20.08
111.30 23.56
111.69 23.56
112.35 30.08
112.61 39.04
112.89 43.53
113.28 43.67
113.81 60.73
113.94 56.63
114.20 63.11
114.46 69.60
115.00 80.44
115.12 86.95
115.27 84.68
115.78 88.78
116.11 89.57
116.40 88.51
116.43 89.90
117.90 80.31
118.18 71.32
118.42 72.51
118.70 67.48
118.83 61.13
119.25 60.34
119.37 54.51
119.65 55.18
120.08 50.28
120.12 48.96
120.84 54.18
120.95 51.87
121.24 56.49
121.50 53.01
121.64 54.44
121.73 51.74
121.84 52.53
122.14 53.72
122.19 52.40
122.44 53.59
122.45 54.91
122.64 51.61
122.76 53.17
123.08 50.79
123.10 50.15
123.34 49.51
123.39 50.81
123.88 50.28
124.25 46.58
124.26 44.06
124.53 43.67
125.18 38.77
125.81 32.16
126.10 32.55
127.32 21.71
127.70 21.18
127.96 18.27
128.22 18.66
128.62 15.71
128.89 16.24
129.30 13.94
129.56 14.47
129.96 12.22
130.21 12.72
130.53 10.83
130.93 10.61
131.15 11.24
131.84 10.06
131.93 11.12
132.71 9.87
133.06 13.17
133.38 12.73
134.17 16.97
134.31 22.37
134.85 30.83
135.38 43.01
135.62 40.09
135.64 50.81
135.75 54.05
136.16 56.10
136.80 50.22
137.21 49.36
138.29 25.41
138.56 26.73
139.98 13.09
140.03 11.92
140.32 14.53
140.55 13.80
140.85 16.25
141.24 15.81
141.45 17.92
141.59 16.51
141.99 20.65
142.25 20.19
142.76 27.79
142.91 24.95
143.72 37.66
143.79 35.37
144.65 29.11
144.91 30.32
145.71 25.74
145.84 24.80
146.54 27.73
146.74 30.57
147.30 31.11
147.42 30.30
148.33 31.23
148.38 30.68
148.93 31.19
149.09 31.74
149.24 28.43
149.49 29.03
149.96 24.55
150.69 23.48
151.83 18.06
151.89 19.39
152.41 18.27
152.96 19.45
153.02 18.53
153.47 19.42
153.71 18.78
153.91 19.44
154.08 17.74
154.54 18.92
154.65 18.20
155.61 18.79
156.78 15.75
157.06 16.08
157.54 12.68
157.84 13.40
158.51 12.73
158.57 11.85
159.45 11.27
159.57 10.33
160.11 8.81
160.24 9.81
160.90 9.27
160.90 8.08
161.17 8.48
161.43 8.10
161.59 8.72
161.83 7.91
162.44 8.48
162.61 7.94
163.41 8.75
163.43 8.19
163.94 8.99
163.96 8.33
164.60 8.23
164.87 8.74
165.81 8.50
166.10 8.08
166.74 8.91
167.02 8.48
167.67 9.68
167.96 9.28
168.90 9.81
168.96 10.34
169.57 9.77
169.76 11.28
170.00 10.75
171.01 13.77
171.12 13.13
171.79 13.71
172.83 19.14
173.19 19.13
173.52 21.06
173.73 20.38
173.87 21.65
174.27 21.90
174.41 25.94
174.94 27.39
175.20 33.48
175.71 35.07
175.84 40.49
176.48 43.27
176.51 46.84
177.34 51.47
177.62 57.30
177.69 55.18
177.87 53.26
178.08 54.46
178.45 49.43
178.76 49.62
179.02 43.53
179.43 42.08
179.96 28.98
180.21 26.40
180.56 26.57
180.57 26.20
181.14 26.43
181.24 25.51
181.68 24.93
181.74 27.13
181.97 28.85
182.05 26.93
182.14 29.78
182.30 27.53
182.59 28.72
182.72 26.93
183.04 27.67
183.21 28.76
183.33 27.92
183.75 29.99
184.06 29.78
184.28 32.07
184.71 32.49
185.40 37.78
185.61 34.01
186.02 33.86
186.20 30.07
186.79 28.72
186.97 25.44
187.34 25.15
188.45 17.65
188.84 16.25
189.08 16.77
189.50 14.08
189.90 13.69
189.92 11.67
190.37 12.04
190.41 12.90
190.90 11.40
190.93 12.58
192.29 9.27
192.33 8.79
193.23 10.21
193.34 9.73
193.78 11.15
194.07 10.20
194.54 10.43
194.93 9.64
195.39 9.82
195.98 10.86
196.08 10.05
196.45 11.78
197.00 8.90
197.03 9.95
197.70 7.15
198.07 10.13
198.10 8.48
198.83 9.67
198.85 10.46
199.27 9.80
199.46 9.46
200.46 11.78
200.73 11.38
201.38 12.37
201.92 9.72
202.06 10.52
203.14 7.67
203.52 7.95
203.93 7.02
204.13 7.55
204.39 6.66
204.63 7.15
206.35 5.53
206.57 6.00
207.21 6.57
207.33 5.76
208.23 7.93
208.52 7.68
208.92 7.15
209.21 7.56
209.41 6.62
209.88 6.89
211.48 4.50
211.70 5.00
212.39 5.37
212.51 4.53
212.84 4.31
212.92 5.17
213.26 4.38
213.44 5.24
213.70 4.57
214.15 4.97
214.24 5.71
215.55 5.20
215.65 6.01
216.28 6.16
216.55 6.87
216.73 5.56
216.95 6.23
217.25 6.03
217.47 5.46
217.93 5.50
218.26 5.83
218.56 5.04
219.31 4.73
219.97 4.72
220.10 5.61
220.79 4.23
220.87 4.94
221.87 4.64
222.07 4.12
222.58 4.47
222.69 5.02
223.21 4.51
223.24 5.22
223.86 4.54
223.90 5.22
224.48 4.29
224.54 5.04
225.22 4.73
225.28 3.86
225.54 4.13
225.76 4.72
225.84 3.93
226.52 4.23
226.60 4.94
226.98 4.02
227.78 3.89
228.29 4.67
228.62 4.29
229.12 4.90
229.46 4.16
229.83 4.48
230.28 3.54
230.50 4.06
230.91 3.03
231.18 3.63
231.79 3.99
231.97 3.45
232.70 4.86
编辑：修订并简化
脚本：（适用于gnuplot>=5.2.0）
### a simple gnuplot peak finder
reset session
FILE = "SO28173128.dat"
colX = 1
colY = 2
# extract all peaks
set table $Temp
plot y2=y1=x2=x1=NaN FILE u (x0=x1,x1=x2,x2=column(colX), \
y0=y1,y1=y2,y2=column(colY), \
y0<y1 && y1>=y2 ? sprintf("%g %g",x1,y1) : '') w table
set table $Peaks # remove empty lines and store first values in x0,y0 for later use
plot $Temp u (column(-2)==0 && $0==0?x0=$1:$1):(column(-2)==0 && $0==0?y0=$2:$2) w table
unset table
isNaN(v) = v!=v # check if value is NaN
min(a,b) = isNaN(a) && isNaN(b) ? NaN : isNaN(a) ? b : isNaN(b) ? a : a<b ? a : b # get minimum incl. NaN
# create prominence table
set print $Prominence
do for [n0=0:|$Peaks|-1] {
xn = yn = xp = yp = NaN
stats $Peaks u ($0<n0 && $2>y0 ? (xn=$1,yn=$2) : 0, \
$0>n0 && $2>y0 && yp!=yp ? (xp=$1,yp=$2) : 0, \
$0==n0+1 ? (x1=$1, y1=$2) : 0 ) nooutput
print sprintf("%g %g %g",x0,y0, min(x0-xn,xp-x0))
x0=x1
y0=y1
}
set print
set key noautotitle
set offsets 0,0,1,0
set grid y
# filter Peaks
stats $Prominence u 3 name "P" nooutput # get min, max
Filter(col,t) = (!valid(col) ? 0 : (1-(column(col)-P_min)/(P_max-P_min))*99+1)<=t ? $2 : NaN
Threshold = 100
set label 1 at graph 0.02,0.95 sprintf("Threshold: %g",Threshold)
plot FILE u colX:colY w l lc rgb "blue" ti "Spectrum", \
$Prominence u 1:(Filter(3,Threshold)) w impulses lc rgb "red", \
$Prominence u 1:(Filter(3,Threshold)):1 w labels offset 0,1
### end of script
结果：（对于不同的阈值）
- theozh
网页内容由stack overflow 提供, 点击上面的可以查看英文原文，
原文链接
原文链接
set table "table"; plot ...; unset table; plot "< grep "i" table" w l。 - Miguellp，那么只有点会出现。 - lambertmular