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This article introduces the relevant knowledge of "the use of dcast and melt in R language". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1. Picture caption

two。 Examples

Sample data:

Set.seed (123)

Dat = data.frame (ID = paste0 ("ID_", 1:10), y1 = rnorm (10), y2=rnorm (10), y3=rnorm (10), y4 = rnorm (10))

Dat

Result

> dat

ID y1 y2 y3 y4

1 ID_1-0.56047565 1.2240818-1.0678237 0.42646422

2 ID_2-0.23017749 0.3598138-0.2179749-0.29507148

3 ID_3 1.55870831 0.4007715-1.0260044 0.89512566

4 ID_4 0.07050839 0.1106827-0.7288912 0.87813349

5 ID_5 0.12928774-0.5558411-0.6250393 0.82158108

6 ID_6 1.71506499 1.7869131-1.6866933 0.68864025

7 ID_7 0.46091621 0.4978505 0.8377870 0.55391765

8 ID_8-1.26506123-1.9666172 0.1533731-0.06191171

9 ID_9-0.68685285 0.7013559-1.1381369-0.30596266

10 ID_10-0.44566197-0.4727914 1.2538149-0.380471003. Change to three columns: ID,trait,ymelt code re1 = melt (data = dat,id.vars=c ("ID"), variable.name= "Loc", value.name= "y")

Head (re1)

Result preview

> head (re1)

ID Loc y

1 ID_1 Y1-0.56047565

2 ID_2 Y1-0.23017749

3 ID_3 y1 1.55870831

4 ID_4 y1 0.07050839

5 ID_5 y1 0.12928774

6 ID_6 y1 1.715064994. Dcast code dcast (data=re1,ID ~ Loc)

Result

> dcast (data=re1,ID ~ Loc)

Using 'y'as value column. Use 'value.var' to override

ID y1 y2 y3 y4

1 ID_1-0.56047565 1.2240818-1.0678237 0.42646422

2 ID_10-0.44566197-0.4727914 1.2538149-0.38047100

3 ID_2-0.23017749 0.3598138-0.2179749-0.29507148

4 ID_3 1.55870831 0.4007715-1.0260044 0.89512566

5 ID_4 0.07050839 0.1106827-0.7288912 0.87813349

6 ID_5 0.12928774-0.5558411-0.6250393 0.82158108

7 ID_6 1.71506499 1.7869131-1.6866933 0.68864025

8 ID_7 0.46091621 0.4978505 0.8377870 0.55391765

9 ID_8-1.26506123-1.9666172 0.1533731-0.06191171

10 ID_9-0.68685285 0.7013559-1.1381369-0.305962665. Command parsing

Melt means merging, turning wide data into long data. For example, in the field data, ID,Loc,rep1, rep2, re3, the rep1,rep2,rep3 here repeats the values of 1 and 2, and you need to change the data into four columns of ID,Loc,Rep,y. So you can use the melt command

Melt (dat,c ("ID", "Loc") > ex1 = data.frame (Cul = rep (1Jap10), Loc=rep (1purl 2), rep2=rnorm (20), rep3=rnorm (20))

> head (ex1)

Cul Loc rep1 rep2 rep3

11 1-0.71040656 0.1176466 0.7017843

2 21 0.25688371-0.9474746-0.2621975

3 31-0.24669188-0.4905574-1.5721442

4 41-0.34754260-0.2560922-1.5146677

5 51-0.95161857 1.8438620-1.6015362

6 61-0.04502772-0.6519499-0.5309065 > ex1_re = melt (ex1,c ("Cul", "Loc"))

> head (ex1_re)

Cul Loc variable value

1 1 1 rep1-0.71040656

2 2 1 rep1 0.25688371

3 3 1 rep1-0.24669188

4 4 1 rep1-0.34754260

5 51 rep1-0.95161857

6 6 1 rep1-0.04502772

Dcast is long data and widened data, so if ex1_re wants to change back, use dcast (ex1_re, Cul + Loc ~ variable), the left side of the ~ sign is the same column name, the right side is the column name that needs to be extended, and the omitted value is the data that needs to be populated.

> dcast (ex1_re,Cul+Loc~variable)

Cul Loc rep1 rep2 rep3

11 1-0.71040656 0.11764660 0.7017843

2 1 2-0.57534696 1.44455086 0.7877388

3 21 0.25688371-0.94747461-0.2621975

422 0.60796432 0.45150405 0.7690422

5 31-0.24669188-0.49055744-1.5721442

6 32-1.61788271 0.04123292 0.3322026

7 41-0.34754260-0.25609219-1.5146677

8 42-0.05556197-0.42249683-1.0083766

95-0.95161857 1.84386201-1.6015362

10 52 0.51940720-2.05324722-0.1194526

11 6 1-0.04502772-0.65194990-0.5309065

12 6 2 0.30115336 1.13133721-0.2803953

13 7 1-0.78490447 0.23538657-1.4617556

14 7 2 0.10567619-1.46064007 0.5629895

15 8 1-1.66794194 0.07796085 0.6879168

16 8 2-0.64070601 0.73994751-0.3724388

17 9 1-0.38022652-0.96185663 2.1001089

18 9 2-0.84970435 1.90910357 0.9769734

19 10 1 0.91899661-0.07130809-1.2870305 "how to use dcast and melt in R language" ends here. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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