ค้นหาสตริงที่มีอักขระคล้ายกันในการตั้งค่ากลุ่มใน R

> dput(mydf)
structure(list(pID = structure(c(69L, 69L, 69L, 69L, 69L, 69L, 
69L, 69L, 69L, 73L, 73L, 73L, 73L), .Label = c("S001", "S002", 
"S003", "S004", "S005", "S006", "S007", "S009", "S012", "S013", 
"S014", "S015", "S016", "S017", "S020", "S021", "S022", "S025", 
"S027", "S028", "S029", "S030", "S032", "S035", "S036", "S038", 
"S039", "S040", "S041", "S042", "S043", "S044", "S045", "S047", 
"S048", "S049", "S050", "S051", "S052", "S053", "S056", "S057", 
"S058", "S059", "S060", "S061", "S062", "S063", "S064", "S065", 
"S066", "S067", "S069", "S070", "S071", "S073", "S075", "S076", 
"S077", "S078", "S079", "S080", "S081", "S082", "S083", "S084", 
"S087", "S088", "S089", "S090", "S091", "S093", "S095", "S097", 
"S099", "S100", "S101", "S103", "S104", "S105", "S106", "S107", 
"S109", "S110", "S112", "S113", "S114", "S115", "S116", "S117", 
"S118", "S119", "S121", "S123", "S124", "S125", "S127", "S128", 
"S129", "S130", "S133", "S134", "S135", "S136", "S138", "S139", 
"S141", "S142", "S143", "S144", "S145", "S146", "S149", "S150", 
"S151", "S152", "S153", "S154", "S155", "S156", "S157", "S161", 
"S163", "S164", "S166", "S168", "S170", "S171", "S172", "S176", 
"S177", "S179", "S180", "S182", "S183", "S188", "S189", "S190", 
"S191", "S192", "S195", "S197", "S200", "S201", "S202", "S204", 
"S211", "S214", "S217", "S218", "S220", "S222", "S224", "S229", 
"S231", "S234", "S235", "S238", "S246", "S250", "S251", "S254", 
"S327", "S333", "S338", "S441", "S467", "S486", "S503", "S523", 
"S532"), class = "factor"), tID = structure(c(9L, 13L, 14L, 18L, 
23L, 27L, 28L, 10L, 19L, 8L, 14L, 17L, 23L), .Label = c("", "3T1_1", 
"3T3_1", "3T3_2", "3T4_1", "3T4_2", "T", "T1", "T1_1", "T1_2", 
"T1_3", "T1_4", "T11", "T2", "T2_1", "T2_2", "T3", "T3_1", "T3_2", 
"T4", "T4_1", "T4_2", "T5", "T5_1", "T5_2", "T6", "T8", "T9"), class = "factor"), 
    sID = structure(c(25L, 25L, 25L, 25L, 25L, 25L, 25L, NA, 
    NA, 27L, 27L, NA, 27L), .Label = c("", "P1", "P10", "P11", 
    "P12", "P13", "P14", "P15", "P16", "P17", "P18", "P19", "P2", 
    "P20", "P21", "P22", "P23", "P24", "P25", "P26", "P27", "P28", 
    "P29", "P3", "P30", "P31", "P32", "P33", "P34", "P35", "P36", 
    "P37", "P38", "P39", "P4", "P40", "P41", "P42", "P43", "P44", 
    "P45", "P5", "P6", "P7", "P8", "P9"), class = "factor")), class = "data.frame", row.names = c(NA, 
-13L))

ใน data frame ด้านบน ผมอยากจะทำ 2 อย่าง คือ

1. ในคอลัมน์ sID ให้กรอกค่า NA ด้วยสตริงเดียวกันกับแถวที่เหลือในคอลัมน์นั้น โดยขึ้นอยู่กับค่าในคอลัมน์ pID ดังนั้น S089 ทั้งหมดจะมี P30 ใน sID
2. สร้างคอลัมน์ใหม่ จัดกลุ่มตาม pID จากนั้นทำเครื่องหมายแต่ละแถวเป็น ไม่ซ้ำกัน หากค่า tID ก่อน _ เป็น แตกต่างมิฉะนั้น ซ้ำ ดังนั้น S089 จะถูกทำเครื่องหมายเป็น ซ้ำ สำหรับ T1_1, T1_2 และ T3_1 และ T3_2 และแถวที่เหลือจะถูกทำเครื่องหมายว่า ไม่ซ้ำกัน

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