按數字列排序字符矩陣

Question

我正在處理從包含數字和字符的csv讀取的矩陣。 這是一個較小的矩陣，但基本上是我正在使用的矩陣：

[,1] [,2] [,3]         [,4]    [,5]    [,6]    [,7]    [,8]    [,9]
V2  "A"  "1"  "Sample X1"  "34712" "39390" "38858" "38574" "38660" 
V3  "A"  "2"  "Sample X2"  "35333" "39940" "40533" "39936" "40669" 
V4  "A"  "3"  "Sample X3"  "33612" "39601" "38658" "39220" "39465" 
V5  "A"  "4"  "Sample X4"  "34309" "39200" "38597" "39820" "40081" 
V6  "A"  "5"  "Sample X5"  "33637" "39404" "40497" "39388" "40033" 
V7  "A"  "6"  "Sample X6"  "35314" "39522" "40345" "38624" "40306" 
V8  "A"  "7"  "Sample X7"  "35548" "39000" "41408" "38310" "39849" 
V9  "A"  "8"  "Sample X8"  "33972" "39930" "39777" "39582" "39570" 
V10 "A"  "9"  "Sample X9"  "34808" "39857" "39252" "39248" "38465" 
V11 "A"  "10" "Sample X10" "34316" "39798" "39776" "39516" "38812" 
V12 "A"  "11" "Sample X11" "34476" "38581" "39672" "38997" "38794" 
V13 "A"  "12" "Sample X12" "36246" "38809" "37872" "38100" "36925" 
V14 "B"  "1"  "Sample X13" "33642" "40201" "40202" "39320" "40426" 
V15 "B"  "2"  "Sample X14" "33381" "40624" "40349" "41350" "40490" 
V16 "B"  "3"  "Sample X15" "34465" "42096" "41194" "40613" "40416" 
V17 "B"  "4"  "Sample X16" "33957" "41905" "42273" "40710" "40681" 
V18 "B"  "5"  "Sample X17" "33877" "42040" "42226" "40788" "41261" 
V19 "B"  "6"  "Sample X18" "33970" "41860" "41149" "41093" "40877" 
V20 "B"  "7"  "Sample X19" "34745" "42040" "40186" "40862" "41044" 
V21 "B"  "8"  "Sample X20" "34140" "41274" "39880" "40356" "40496" 
V22 "B"  "9"  "Sample X21" "33929" "40652" "41410" "40760" "40718" 
V23 "B"  "10" "Sample X22" "33684" "39220" "40478" "41500" "40094"
V24 "B"  "11" "Sample X23" "33141" "41446" "41121" "40726" "41020"
V25 "B"  "12" "Sample X24" "33405" "38481" "37716" "38562" "38218" 
V26 "C"  "1"  "Sample X25" "71560" "86402" "85614" "84273" "83264" 
V27 "C"  "2"  "Sample X26" "72144" "86266" "88082" "87672" "87356" 
V28 "C"  "3"  "Sample X27" "71946" "90201" "89156" "88386" "88006" 
V29 "C"  "4"  "Sample X28" "71758" "89108" "88225" "86006" "88654" 
V30 "C"  "5"  "Sample X29" "71144" "86558" "88614" "87028" "88809" 
V31 "C"  "6"  "Sample X30" "70504" "89230" "88869" "86653" "86356" 
V32 "C"  "7"  "Sample X31" "67874" "88405" "84878" "84914" "85425" 
V33 "C"  "8"  "Sample X32" "70273" "87865" "87529" "87945" "86172" 

我想按沒有標題的第二列對矩陣進行排序：

A 1 . . .
B 1
C 1
A 2
B 2
C 2
A 3
. 
.
.
A 12
B 12
C 12 . . .

我環顧四周，發現您可以使用訂單：

data <- data[order(data[,2],]

但結果是這樣的：

A 1 . . .
B 1
c 1
A 10
B 10
C 10
A 11
B 11
C 11
A 12
B 12
C 12
A 2
B 2
C 2
.
.
.
A 9
B 9
C 9 . . .

是否因為此矩陣是字符矩陣？ 我該如何僅使第二列成為數字，以便可以據此對它進行排序？

謝謝

Answer 1

當您想在各列中混合使用類（例如，數字和字符）時，將數據放在矩陣中是個壞主意。 相反，您應該使用數據框。

理想情況下，使用read.csv或read.table將數據讀入數據幀。 否則，使用as.data.frame將矩陣強制為一個數據as.data.frame 。

給定矩陣m （在您的情況下為data ）：

d <- as.data.frame(m, stringsAsFactors=FALSE)
d[, 3] <- as.numeric(d[, 3]) # coerce the relevant column to numeric
d[order(d[, 3]), ]

請注意，您可以根據需要使用m[order(as.numeric(m[, 3])), ]對矩陣進行m[order(as.numeric(m[, 3])), ] ，但是結果列仍然都是character 。

注意：您看到的排序行為的解釋是，對於字符向量，任何以1開頭（例如10 ）的東西都在2之前。