I am new to 'for' loops in R, and I'm trying to create a new column in the dataframe and pass a formula through it, with the output being a calculated value in each cell. Here is the data I am working with:
data <- data.frame(plot1=c(133,
134,
115,
135,
119,
41,
96,
147,
64,
18,
123,
198,
40,
142,
131,
175,
52,
7,
100,
30,
197,
200,
45,
149,
170,
87,
191,
90,
50,
168,
153,
70,
98,
76,
12,
83,
101,
26,
62,
96,
52,
97,
90,
65,
9,
146,
182,
174,
15,
78,
165,
29,
186,
132,
167,
6,
43,
135,
148,
49,
64,
102,
195,
103,
105,
75,
189,
28,
117,
112,
187,
13,
109,
123,
61,
13,
160,
172,
125,
34,
75,
89,
19,
121,
136,
3,
32,
161,
111,
158,
135,
78,
133,
7,
182,
159,
99,
155,
80,
186,
120,
74,
119,
105,
157,
187,
46,
92,
25,
48,
129,
156,
180,
106,
115,
188,
120,
133,
61,
152,
152,
31,
84,
8,
20,
40,
59,
136,
84,
111,
167,
53,
40,
121,
29,
127,
135,
177,
54,
103,
41,
15,
21,
108,
105,
139,
73,
126,
59,
165,
91,
56,
53,
126,
26,
124,
128,
86,
109,
50,
40,
8,
21,
177,
198,
128,
160,
97,
12,
128,
102,
57,
197,
167,
90,
33,
59,
79,
167,
5,
52,
58,
22,
200,
38,
163,
77,
188,
136,
26,
10,
37,
179,
98,
170,
35,
30,
144,
61,
58,
141,
165,
37,
98,
2,
103,
133,
88,
172,
114,
132,
89,
170,
62,
12,
27),
plot2=c(412,
303,
10,
45,
161,
181,
450,
647,
43,
407,
170,
470,
404,
505,
293,
173,
217,
238,
318,
443,
378,
317,
29,
64,
192,
249,
550,
328,
605,
552,
58,
226,
502,
193,
506,
589,
160,
261,
515,
563,
550,
645,
488,
547,
434,
652,
70,
573,
623,
351,
450,
384,
82,
315,
517,
626,
524,
650,
466,
8,
452,
624,
306,
431,
460,
587,
619,
139,
43,
124,
38,
394,
53,
436,
625,
173,
509,
32,
115,
156,
465,
656,
584,
636,
255,
212,
317,
154,
153,
111,
554,
653,
15,
32,
118,
532,
415,
615,
124,
416,
546,
51,
503,
448,
612,
551,
286,
347,
52,
435,
592,
138,
182,
622,
646,
5,
158,
473,
640,
500,
7,
578,
1,
644,
230,
374,
452,
307,
271,
462,
647,
648,
358,
262,
614,
79,
278,
534,
68,
359,
357,
106,
589,
575,
457,
555,
252,
418,
371,
654,
88,
609,
589,
215,
435,
82,
600,
266,
510,
307,
537,
148,
536,
290,
36,
301,
27,
129,
77,
595,
506,
431,
293,
232,
108,
246,
354,
347,
460,
384,
452,
261,
132,
499,
463,
187,
422,
319,
48,
284,
241,
151,
611,
496,
572,
501,
644,
387,
480,
221,
146,
39,
400,
361,
531,
69,
539,
295,
249,
638,
289,
83,
404,
289,
547,
324))
The new column created is data$newCol, and I'm trying to calculate the area of a circle using the data in data$plot2 and then multiply that value by data$plot1. The result should be in the data$newCol column.
Here is what I have tried:
data$newCol <- for(i in data$newCol) {
((3.14(data$plot2^2)) * (data$plot1)
}
However, I keep getting this error:
Error: attempt to apply non-function
Can someone help me properly write this loop?
CodePudding user response：
I see a few issues with what you're doing:
- To multiply
3.14by something you need to supply a multiplication operator*. When you write3.14(x)that is the construction of a function where3.14is the name of the function andxis it's arguments. That's what's causing the error
Error: attempt to apply non-function
- If
data$newColdoesn't exist yet you can't loop over it. - This doesn't need to be a loop because those mathematical operations are vectorized so they will just act element by element down the vectors supplied if they are the same length.
Rhas a built in constant forpiso you can get better precision than3.14if you're interested.
So with that in mind, try this:
data$newCol <- pi * (data$plot2^2) * data$plot1
CodePudding user response：
If I understood you correctly you are looking for:
data$newCol <- pi*data$plot2^2 * data$plot1
The above would give you a new column. In R, these operations are vectorised, thus, loops are not needed.